Immunization of Health-Care Workers: Recommendations of the Advisory Committee on Immunization Practices (ACIP) and the Hospital Infection Control Practices Advisory Committee (HICPAC)

Summary

This report summarizes recommendations of the Advisory Committee on Immunization Practices (ACIP) concerning the use of certain immunizing agents in health-care workers (HCWs) in the United States. It was prepared in consultation with the Hospital Infection Control Practices Advisory Committee (HICPAC) and is consistent with current HICPAC guidelines for infection control in health-care personnel. These recommendations can assist hospital administrators, infection control practitioners, employee health physicians, and HCWs in optimizing infection prevention and control programs. Background information for each vaccine-preventable disease and specific recommendations for use of each vaccine are presented. The diseases are grouped into three categories: a) those for which active immunization is strongly recommended because of special risks for HCWs; b) those for which immunoprophylaxis is or may be indicated in certain circumstances; and c) those for which protection of all adults is recommended. This report reflects current ACIP recommendations at the time of publication. ACIP statements on individual vaccines and disease updates in MMWR should be consulted for more details regarding the epidemiology of the diseases, immunization schedules, vaccine doses, and the safety and efficacy of the vaccines.

INTRODUCTION

Because of their contact with patients or infective material from patients, many health-care workers (HCWs)(e.g., physicians, nurses, emergency medical personnel, dental professionals and students, medical and nursing students, laboratory technicians, hospital volunteers, and administrative staff) are at risk for exposure to and possible transmission of vaccine-preventable diseases. Maintenance of immunity is therefore an essential part of prevention and infection control programs for HCWs. Optimal use of immunizing agents safeguards the health of workers and protects patients from becoming infected through exposure to infected workers (Table_1) (1-15). Consistent immunization programs could substantially reduce both the number of susceptible HCWs in hospitals and health departments and the attendant risks for transmission of vaccine-preventable diseases to other workers and patients (16). In addition to HCWs in hospitals and health departments, these recommendations apply to those in private physicians' offices, nursing homes, schools, and laboratories, and to first responders.

Any medical facility or health department that provides direct patient care is encouraged to formulate a comprehensive immunization policy for all HCWs. The American Hospital Association has endorsed the concept of immunization programs for both hospital personnel and patients (17). The following recommendations concerning vaccines of importance to HCWs should be considered during policy development (Table_2).

BACKGROUND

Diseases for Which Immunization Is Strongly Recommended

On the basis of documented nosocomial transmission, HCWs are considered to be at significant risk for acquiring or transmitting hepatitis B, influenza, measles, mumps, rubella, and varicella. All of these diseases are vaccine-preventable.

Hepatitis B

Hepatitis B virus (HBV) infection is the major infectious hazard for health-care personnel. During 1993, an estimated 1,450 workers became infected through exposure to blood and serum-derived body fluids, a 90% decrease from the number estimated to have been thus infected during 1985 (18-20). Data indicate that 5%-10% of HBV-infected workers become chronically infected. Persons with chronic HBV infection are at risk for chronic liver disease (i.e., chronic active hepatitis, cirrhosis, and primary hepatocellular carcinoma) and are potentially infectious throughout their lifetimes. An estimated 100-200 health-care personnel have died annually during the past decade because of the chronic consequences of HBV infection (CDC, unpublished data).

The risk for acquiring HBV infection from occupational exposures is dependent on the frequency of percutaneous and permucosal exposures to blood or body fluids containing blood (21-25). Depending on the tasks he or she performs, any health-care or public safety worker may be at high risk for HBV exposure. Workers performing tasks involving exposure to blood or blood-contaminated body fluids should be vaccinated. For public safety workers whose exposure to blood is infrequent, timely postexposure prophylaxis may be considered, rather than routine preexposure vaccination.

In 1987, the Departments of Labor and Health and Human Services issued a Joint Advisory Notice regarding protection of employees against workplace exposure to HBV and human immunodeficiency virus (HIV), and began the process of rulemaking to regulate such exposures (26). The Federal Standard issued in December, 1991 under the Occupational Safety and Health Act mandates that hepatitis B vaccine be made available at the employer's expense to all health-care personnel who are occupationally exposed to blood or other potentially infectious materials (27). Occupational exposure is defined as "...reasonably anticipated skin, eye, mucous membrane, or parenteral contact with blood or other potentially infectious materials that may result from the performance of an employee's duties (27)." The Occupational Safety and Health Administration (OSHA) follows current ACIP recommendations for its immunization practices requirements (e.g., preexposure and postexposure antibody testing). These regulations have accelerated and broadened the use of hepatitis B vaccine in HCWs and have ensured maximal efforts to prevent this occupational disease (23).

Prevaccination serologic screening for prior infection is not indicated for persons being vaccinated because of occupational risk. Postvaccination testing for antibody to hepatitis B surface antigen (anti-HBs) response is indicated for HCWs who have blood or patient contact and are at ongoing risk for injuries with sharp instruments or needlesticks (e.g., physicians, nurses, dentists, phlebotomists, medical technicians and students of these professions). Knowledge of antibody response aids in determining appropriate postexposure prophylaxis.

Vaccine-induced antibodies to HBV decline gradually over time, and less than or equal to 60% of persons who initially respond to vaccination will lose detectable antibodies over 12 years (28; CDC, unpublished data). Studies among adults have demonstrated that, despite declining serum levels of antibody, vaccine-induced immunity continues to prevent clinical disease or detectable viremic HBV infection (29). Therefore, booster doses are not considered necessary (1). Periodic serologic testing to monitor antibody concentrations after completion of the three-dose series is not recommended. The possible need for booster doses will be assessed as additional data become available.

Asymptomatic HBV infections have been detected in vaccinated persons by means of serologic testing for antibody to hepatitis B core antigen (anti-HBc) (1). However, these infections also provide lasting immunity and are not associated with HBV-related chronic liver disease.

Influenza

During community influenza outbreaks, admitting patients infected with influenza to hospitals has led to nosocomial transmission of the disease (30,31), including transmission from staff to patients (32). Transmission of influenza among medical staff causes absenteeism and considerable disruption of health care (33-36; CDC, unpublished data). In addition, influenza outbreaks have caused morbidity and mortality in nursing homes (36-41). In a recent study of long-term care facilities with uniformly high patient influenza vaccination levels, patients in facilities in which greater than 60% of the staff had been vaccinated against influenza experienced less influenza-related mortality and illness, compared with patients in facilities with no influenza-vaccinated staff (42).

Measles, Mumps, and Rubella

Measles. Nosocomial measles transmission has been documented in the offices of private physicians, in emergency rooms, and on hospital wards (43-49). Although only 3.5% of all cases of measles reported during 1985- 1989 occurred in medical settings, the risk for measles infection in medical personnel is estimated to be thirteenfold that for the general population (45,49-52). During 1990-1991, 1,788 of 37,429 (4.8%) measles cases were reported to have been acquired in medical settings. Of these, 668 (37.4%) occurred among HCWs, 561 (84%) of whom were unvaccinated; 187 (28%) of these HCWs were hospitalized with measles and three died (CDC, unpublished data). Of the 3,659 measles cases reported during 1992-1995, the setting of transmission was known for 2,765; 385 (13.9%) of these cases occurred in medical settings (CDC, unpublished data).

Although birth before 1957 is generally considered acceptable evidence of measles immunity, serologic studies of hospital workers indicate that 5%-9% of those born before 1957 are not immune to measles (53,54). During 1985-1992, 27% of all measles cases among HCWs occurred in persons born before 1957 (CDC, unpublished data).

Mumps. In recent years, a substantial proportion of reported mumps has occurred among unvaccinated adolescents and young adults on college campuses and in the workplace (55-58). Outbreaks of mumps in highly vaccinated populations have been attributed to primary vaccine failure (59,60). During recent years, the overall incidence of mumps has fluctuated only minimally but an increasing proportion of cases has been reported in persons aged greater than or equal to 15 years (61). Mumps transmission in medical settings has been reported nationwide (62, CDC, unpublished data). Programs to ensure that medical personnel are immune to mumps are prudent and are easily linked with measles and rubella control programs (5).

Rubella. Nosocomial rubella outbreaks involving both HCWs and patients have been reported (63). Although vaccination has decreased the overall risk for rubella transmission in all age groups in the United States by greater than or equal to 95%, the potential for transmission in hospital and similar settings persists because 10%-15% of young adults are still susceptible (6,64-67). In an ongoing study of rubella vaccination in a health maintenance organization, 7,890 of 92,070 (8.6%) women aged greater than or equal to 29 years were susceptible to rubella (CDC, unpublished data). Although not as infectious as measles, rubella can be transmitted effectively by both males and females. Transmission can occur whenever many susceptible persons congregate in one place. Aggressive rubella vaccination of susceptible men and women with trivalent measles-mumps-rubella (MMR) vaccine can eliminate rubella (as well as measles) transmission (68).

Persons born before 1957 generally are considered to be immune to rubella. However, findings of seroepidemiologic studies indicate that about 6% of HCWs (including persons born in 1957 or earlier) do not have detectable rubella antibody (CDC, unpublished data).

Varicella

Nosocomial transmission of varicella zoster virus (VZV) is well recognized (69-80). Sources for nosocomial exposure of patients and staff have included patients, hospital staff, and visitors (e.g., the children of hospital employees) who are infected with either varicella or zoster. In hospitals, airborne transmission of VZV from persons who had varicella or zoster to susceptible persons who had no direct contact with the index case-patient has occurred (81-85). Although all susceptible hospitalized adults are at risk for severe varicella disease and complications, certain patients are at increased risk: pregnant women, premature infants born to susceptible mothers, infants born at less than 28 weeks' gestation or who weigh less than or equal to 1000 grams regardless of maternal immune status, and immunocompromised persons of all ages (including persons who are undergoing immunosuppressive therapy, have malignant disease, or are immunodeficient).

Varicella Control Strategies

Strategies for managing clusters of VZV infections in hospitals include (16,86-94):

• isolating patients who have varicella and other susceptible patients who are exposed to VZV;

• controlling air flow;

• using rapid serologic testing to determine susceptibility;

• furloughing exposed susceptible personnel or screening these persons daily for skin lesions, fever, and systemic symptoms; and

• temporarily reassigning varicella-susceptible personnel to locations remote from patient-care areas.

Appropriate isolation of hospitalized patients who have confirmed or suspected VZV infection can reduce the risk for transmission to personnel (95).

Identification of the few persons who are susceptible to varicella when they begin employment that involves patient contact is recommended. Only personnel who are immune to varicella should care for patients who have confirmed or suspected varicella or zoster.

A reliable history of chickenpox is a valid measure of VZV immunity. Serologic tests have been used to assess the accuracy of reported histories of chickenpox (76,80,93,95-97). Among adults, 97% to 99% of persons with a positive history of varicella are seropositive. In addition, the majority of adults with negative or uncertain histories are seropositive (range: 71%-93%). Persons who do not have a history of varicella or whose history is uncertain can be considered susceptible, or tested serologically to determine their immune status. In health-care institutions, serologic screening of personnel who have a negative or uncertain history of varicella is likely to be cost effective (8).

If susceptible HCWs are exposed to varicella, they are potentially infective 10-21 days after exposure. They must often be furloughed during this period, usually at substantial cost. Persons in whom varicella develops are infective until all lesions dry and crust (16,35,96-98) (see Other Considerations in Vaccination of Health-Care Workers -- Work Restrictions for Susceptible Workers After Exposure).

Administration of varicella zoster immune globulin (VZIG) after exposure can be costly. VZIG does not necessarily prevent varicella, and may prolong the incubation period by a week or more, thus extending the time during which personnel should not work.

Breakthrough Infection and Transmission of Vaccine Virus to Contacts

Varicella virus vaccine protects approximately 70%-90% of recipients against infection and 95% of recipients against severe disease for at least 7-10 years after vaccination. Significant protection is long-lasting. Breakthrough infections (i.e., cases of varicella) have occurred among vaccinees after exposure to natural varicella virus. Data from all trials in which vaccinees of all ages were actively followed for up to 9 years indicated that varicella developed in 1%-4.4% of vaccinees per year, depending on vaccine lot and time interval since vaccination (Merck and Company, Inc., unpublished data). Unvaccinated persons who contract varicella generally are febrile and have several hundred vesicular lesions. Among vaccinees who developed varicella, in contrast, the median number of skin lesions was less than 50 and lesions were less apt to be vesicular. Most vaccinated persons who contracted varicella were afebrile, and the duration of illness was shorter (Merck and Company, Inc., unpublished data; 99,100).

The rate of transmission of disease from vaccinees who contract varicella is low for vaccinated children, but has not been studied in adults. Ten different trials conducted during 1981-1989 involved 2,141 vaccinated children. Breakthrough infections occurred in 78 children during the 1-8 year follow-up period of active surveillance, resulting in secondary cases in 11 of 90 (12.2%) vaccinated siblings. Among both index and secondary case-patients, illness was mild. Transmission to a susceptible mother from a vaccinated child in whom breakthrough disease occurred also has been reported (Merck and Company, Inc., unpublished data; 101).

Estimates of vaccine efficacy and persistence of antibody in vaccinees are based on research conducted before widespread use of varicella vaccine began to influence the prevalence of natural VZV infection. Thus, the extent to which boosting from exposure to natural virus increases the protection provided by vaccination remains unclear. Whether longer-term immunity may wane as the circulation of natural VZV decreases also is unknown.

Risk for transmission of vaccine virus was assessed in placebo recipients who were siblings of vaccinated children and among healthy siblings of vaccinated leukemic children (102,103). The findings of these studies indicate that healthy vaccinated persons have a minimal risk (estimated to be less than 1%) for transmitting vaccine virus to their contacts. This risk may be increased in vaccinees in whom a varicella-like rash develops after vaccination. Tertiary transmission of vaccine virus to a second healthy sibling of a vaccinated leukemic child also has occurred (103).

Several options for managing vaccinated HCWs who may be exposed to varicella are available. Routine serologic testing for varicella immunity after administration of two doses of vaccine is not considered necessary because 99% of persons become seropositive after the second dose. Seroconversion, however, does not always result in full protection against disease. Institutional guidelines are needed for management of exposed vaccinees who do not have detectable antibody and for those who develop clinical varicella. A potentially effective strategy to identify persons who remain at risk for varicella is to test vaccinated persons for serologic evidence of immunity immediately after they are exposed to VZV. Prompt, sensitive, and specific serologic results can be obtained at reasonable cost with a commercially available latex agglutination (LA) test. Many other methods also have been used to detect antibody to VZV (8). The LA test, which uses latex particles coated with VZV glycoprotein antigens, can be completed in 15 minutes (104,105). Persons with detectable antibody are unlikely to become infected with varicella. Persons who do not have detectable antibody can be retested in 5-6 days. If an anamnestic response is present, these persons are unlikely to contract the disease. HCWs who do not have antibody when retested may be furloughed. Alternatively, the clinical status of these persons may be monitored daily and they can be furloughed at the onset of manifestations of varicella.

More information is needed concerning risk for transmission of vaccine virus from vaccinees with and without varicella-like rash after vaccination. The risk appears to be minimal, and the benefits of vaccinating susceptible HCWs outweigh this potential risk. As a safeguard, institutions may wish to consider precautions for personnel in whom a rash develops after vaccination and for other vaccinated personnel who will have contact with susceptible persons at high risk for serious complications.

Vaccination should be considered for unvaccinated HCWs who lack documented immunity if they are exposed to varicella. However, because the effectiveness of postexposure vaccination is unknown, persons vaccinated after an exposure should be managed in the manner recommended for unvaccinated persons.

Tuberculosis and Bacille-Calmette-Guerin Vaccination

In the United States, Bacille Calmette-Guerin (BCG) vaccine has not been recommended for general use because the population risk for infection with Mycobacterium tuberculosis (TB) is low and the protective efficacy of BCG vaccine uncertain. The immune response to BCG vaccine also interferes with use of the tuberculin skin test to detect M. tuberculosis infection (7). TB prevention and control efforts are focused on interrupting transmission from patients who have active infectious TB, skin testing those at high risk for TB, and administering preventive therapy when appropriate. However, in certain situations, BCG vaccination may contribute to the prevention and control of TB when other strategies are inadequate.

Control of TB

The fundamental strategies for the prevention and control of TB include:

• Early detection and effective treatment of patients with active communicable TB (106).

• Preventive therapy for infected persons. Identifying and treating persons who are infected with M. tuberculosis can prevent the progression of latent infection to active infectious disease (107).

• Prevention of institutional transmission. The transmission of TB is a recognized risk in health-care settings and is of particular concern in settings where HIV-infected persons work, volunteer, visit, or receive care (108). Effective TB infection-control programs should be implemented in health-care facilities and other institutional settings, (e.g., shelters for homeless persons and correctional facilities) (16,109,110).

Role of BCG Vaccination in Prevention of TB Among HCWs

In a few geographic areas of the United States, increased risks for TB transmission in health-care facilities (compared with risks observed in health-care facilities in other parts of the United States) occur together with an elevated prevalence among TB patients of M. tuberculosis strains that are resistant to both isoniazid and rifampin (111-116). Even in such situations, comprehensive application of infection control practices should be the primary strategy used to protect HCWs and others in the facility from infection with M. tuberculosis. BCG vaccination of HCWs should not be used as a primary TB control strategy because a) the protective efficacy of the vaccine in HCWs is uncertain; b) even if BCG vaccination is effective for a particular HCW, other persons in the health-care facility (e.g., patients, visitors, and other HCWs) are not protected against possible exposure to and infection with drug-resistant strains of M. tuberculosis; and c) BCG vaccination may complicate preventive therapy because of difficulties in distinguishing tuberculin skin test responses caused by infection with M. tuberculosis from those caused by the immune response to vaccination.

Hepatitis C and Other Parenterally Transmitted Non-A, Non-B Hepatitis

Hepatitis C virus (HCV) is the etiologic agent in most cases of parenterally transmitted non-A, non-B hepatitis in the United States (117,118). CDC estimates that the annual number of newly acquired HCV infections has ranged from 180,000 in 1984 to 28,000 in 1995. Of these, an estimated 2%-4% occurred among health-care personnel who were occupationally exposed to blood. At least 85% of persons who contract HCV infection become chronically infected, and chronic hepatitis develops in an average of 70% of all HCV-infected persons (117-119). Up to 10% of parenterally transmitted non-A, non-B hepatitis may be caused by other bloodborne viral agents not yet characterized (non-ABCDE hepatitis) (117,120).

Serologic enzyme immunoassays (EIA) licensed for the detection of antibody to HCV (anti-HCV) have evolved since their introduction in 1990 and a third version is now available which detects anti-HCV in greater than or equal to 95% of patients with HCV infection. Interpretation of EIA results is limited by several factors. These assays do not detect anti-HCV in all infected persons and do not distinguish among acute, chronic, or resolved infection. In 80% to 90% of HCV-infected persons, seroconversion occurs an average of 10-12 weeks after exposure to HCV. These screening assays also yield a high proportion (up to 50%) of falsely positive results when they are used in populations with a low prevalence of HCV infection (118,121). Although no true confirmatory test has been developed, supplemental tests for specificity are available (such as the licensed Recombinant Immunoblot Assay {RIBATM}), and should always be used to verify repeatedly reactive results obtained with screening assays.

The diagnosis of HCV infection also is possible by detecting HCV RNA with polymerase chain reaction (PCR) techniques. Although PCR assays for HCV RNA are available from several commercial laboratories on a research-use basis, results vary considerably between laboratories. In a recent study in which a reference panel containing known HCV RNA-positive and -negative sera was provided to 86 laboratories worldwide (122), only 50% were considered to have performed adequately (i.e., by failing to detect one weak positive sample), and only 16% reported faultless results. Both false-positive and false-negative results can occur from improper collection, handling, and storage of the test samples. In addition, because HCV RNA may be detectable only intermittently during the course of infection, a single negative PCR test result should not be regarded as conclusive. Tests also have been developed to quantitate HCV RNA in serum; however, the applicability of these tests in the clinical setting has not been determined.

Most HCV transmission is associated with direct percutaneous exposure to blood, and HCWs are at occupational risk for acquiring this viral infection (123-131). The prevalence of anti-HCV among hospital-based HCWs and surgeons is about 1%(125-128) and 2% among oral surgeons (129,130). In follow-up studies of HCWs who sustained percutaneous exposures to blood from anti-HCV positive patients through unintentional needlesticks or sharps injuries, the average incidence of anti-HCV seroconversion was 1.8% (range: 0%-7%) (132-137). In the only study that used PCR to measure HCV infection by detecting HCV RNA, the incidence of postinjury infection was 10% (136). Although these follow-up studies have not documented transmission associated with mucous membrane or nonintact skin exposures, one case report describes the transmission of HCV from a blood splash to the conjunctiva (138).

Several studies have examined the effectiveness of prophylaxis with immune globulins (IGs) in preventing posttransfusion non-A, non-B hepatitis (139-141). The findings of these studies are difficult to compare and interpret, because of lack of uniformity in diagnostic criteria, mixed sources of donors (volunteer and commercial), and differing study designs (some studies lacked blinding and placebo controls). In some of these studies, IGs appeared to reduce the rate of clinical disease but not overall infection rates. In one study, data indicated that chronic hepatitis was less likely to develop in patients who received IG (139). None of these data have been reanalyzed since anti-HCV testing became available. In only one study was the first dose of IG administered after, rather than before, the exposure; the value of IG for postexposure prophylaxis is thus difficult to assess. The heterogeneous nature of HCV and its ability to undergo rapid mutation, however, appear to prevent development of an effective neutralizing immune response (142), suggesting that postexposure prophylaxis using IG is likely to be ineffective. Furthermore, IG is now manufactured from plasma that has been screened for anti-HCV. In an experimental study in which IG manufactured from anti-HCV negative plasma was administered to chimpanzees one hour after exposure to HCV, the IG did not prevent infection or disease (143).

The prevention of HCV infection with antiviral agents (e.g., alpha interferon) has not been studied. Although alpha interferon therapy is safe and effective for the treatment of chronic hepatitis C (144), the mechanisms of the effect are poorly understood. Interferon may be effective only in the presence of an established infection (145). Interferon must be administered by injection and may cause side effects. Based on these considerations, antiviral agents are not recommended for postexposure prophylaxis of HCV infection.

In the absence of effective prophylaxis, persons who have been exposed to HCV may benefit from knowing their infection status so they can seek evaluation for chronic liver disease and treatment. Sustained response rates to alpha interferon therapy generally are low (10%-20% in the United States). The occurrence of mild to moderate side effects in most patients has required discontinuation of therapy in up to 15% of patients. No clinical, demographic, serum biochemical, serologic, or histologic features have been identified that reliably predict which patients will sustain a long-term remission in response to alpha interferon therapy.

Several studies indicate that interferon treatment begun early in the course of HCV infection is associated with an increased rate of resolved infection. Onset of HCV infection among HCWs after exposure could be detected earlier by using PCR to detect HCV RNA than by using EIA to measure anti-HCV. However, PCR is not a licensed assay and its accuracy is highly variable. In addition, no data are available which indicate that treatment begun early in the course of chronic HCV infection is less effective than treatment begun during the acute phase of infection. Furthermore, alpha interferon is approved for the treatment of chronic hepatitis C only.

IG or antiviral agents are not recommended for postexposure prophylaxis of hepatitis C. No vaccine against hepatitis C is available. Health-care institutions should consider implementing policies and procedures to monitor HCWs for HCV infection after percutaneous or permucosal exposures to blood (146). At a minimum, such policies should include:

• For the source, baseline serologic testing for anti-HCV;

• For the person exposed to an anti-HCV positive source, baseline and follow-up (e.g., 6 months) serologic testing for anti-HCV and alanine aminotransferase activity;

• Confirmation by supplemental anti-HCV testing of all anti-HCV results reported as repeatedly reactive by EIA;

• Education of HCWs about the risk for and prevention of occupational transmission of all blood borne pathogens, including hepatitis C, using up-to-date and accurate information.

Other Diseases for Which Immunization of Health-Care Workers Is or May Be Indicated

Diseases are included in this section for one of the following reasons:

• Nosocomial transmission occurs, but HCWs are not at increased risk as a result of occupational exposure (i.e., hepatitis A),

• Occupational risk may be high, but protection via active or passive immunization is not available (i.e., pertussis), or

• Vaccines are available but are not routinely recommended for all HCWs or are recommended only in certain situations (i.e., vaccinia and meningococcal vaccines).

Hepatitis A

Occupational exposure generally does not increase HCWs' risk for hepatitis A virus (HAV) infection. When proper infection control practices are followed, nosocomial HAV transmission is rare. Outbreaks caused by transmission of HAV to neonatal intensive care unit staff by infants infected through transfused blood have occasionally been observed (147-149). Transmission of HAV from adult patients to HCWs is usually associated with fecal incontinence in the patients. However, most patients hospitalized with hepatitis A are admitted after onset of jaundice, when they are beyond the point of peak infectivity (150). Serologic surveys among many types of HCWs have not identified an elevated prevalence of HAV infection compared with other occupational populations (151-153).

Two specific prophylactic measures are available for protection against hepatitis A -- administration of immune globulin (IG) and hepatitis A vaccine. When administered within 2 weeks after an exposure, IG is greater than 85% effective in preventing hepatitis A (2). Two inactivated hepatitis A vaccines, which can provide long-term preexposure protection, were recently licensed in the United States: HAVRIX (R) (manufactured by SmithKline Beecham Biologicals) and VAQTA (R) (manufactured by Merck & Company, Inc.) (2). The efficacy of these vaccines in preventing clinical disease ranges from 94% to 100%. Data indicate that the duration of clinical protection conferred by VAQTA (R) is at least 3 years, and that conferred by HAVRIX (R) at least 4 years. Mathematical models of antibody decay indicate that protection conferred by vaccination may last up to 20 years (2).

Meningococcal Disease

Nosocomial transmission of Neisseria meningitidis is uncommon. In rare instances, direct contact with respiratory secretions of infected persons (e.g., during mouth-to-mouth resuscitation) has resulted in transmission from patients with meningococcemia or meningococcal meningitis to HCWs. Although meningococcal lower respiratory infections are rare, HCWs may be at increased risk for meningococcal infection if exposed to N. meningitidis-infected patients with active productive coughs. HCWs can decrease the risk for infection by adhering to precautions to prevent exposure to respiratory droplets (16,95).

Postexposure prophylaxis is advised for persons who have had intensive, unprotected contact (i.e., without wearing a mask) with infected patients (e.g., intubating, resuscitating, or closely examining the oropharynx of patients)(16). Antimicrobial prophylaxis can eradicate carriage of N. meningitidis and prevent infections in persons who have unprotected exposure to patients with meningococcal infections (9). Rifampin is effective in eradicating nasopharyngeal carriage of N. meningitidis, but is not recommended for pregnant women, because the drug is teratogenic in laboratory animals. Ciprofloxacin and ceftriaxone in single-dose regimens are also effective in reducing nasopharyngeal carriage of N. meningitidis, and are reasonable alternatives to the multidose rifampin regimen (9). Ceftriaxone also can be used during pregnancy.

Although useful for controlling outbreaks of serogroup C meningococcal disease, administration of quadrivalent A,C,Y,W-135 meningococcal polysaccharide vaccines is of little benefit for postexposure prophylaxis (9). The serogroups A and C vaccines, which have demonstrated estimated efficacies of 85%-100% in older children and adults, are useful for control of epidemics (9). The decision to implement mass vaccination to prevent serogroup C meningococcal disease depends on whether the occurrence of more than one case of the disease represents an outbreak or an unusual clustering of endemic meningococcal disease. Surveillance for serogroup C disease and calculation of attack rates can be used to identify outbreaks and determine whether use of meningococcal vaccine is warranted. Recommendations for evaluating and managing suspected serogroup C meningococcal disease outbreaks have been published (9).

Pertussis

Pertussis is highly contagious. Secondary attack rates among susceptible household contacts exceed 80% (154,155). Transmission occurs by direct contact with respiratory secretions or large aerosol droplets from the respiratory tract of infected persons. The incubation period is generally 7-10 days. The period of communicability starts with the onset of the catarrhal stage and extends into the paroxysmal stage. Vaccinated adolescents and adults, whose immunity wanes 5-10 years after the last dose of vaccine (usually administered at age 4-6 years), are an important source of pertussis infection for susceptible infants. The disease can be transmitted from adult patients to close contacts, especially unvaccinated children. Such transmission may occur in households and hospitals.

Transmission of pertussis in hospital settings has been documented in several reports (156-159). Transmission has occurred from a hospital visitor, from hospital staff to patients, and from patients to hospital staff. Although of limited size (range: 2-17 patients and 5-13 staff), documented outbreaks were costly and disruptive. In each outbreak, larger numbers of staff were evaluated for cough illness and required nasopharyngeal cultures, serologic tests, prophylactic antibiotics, and exclusion from work.

During outbreaks that occur in hospitals, the risk for contracting pertussis among patients or staff is often difficult to quantify because exposure is not well defined. Serologic studies conducted among hospital staff during two outbreaks indicate that exposure to pertussis is much more frequent than the attack rates of clinical disease indicate (154,156-159). Seroprevalence of pertussis agglutinating antibodies correlated with the degree of patient contact and was highest among pediatric house staff (82%) and ward nurses (71%), lowest among nurses with administrative responsibilities (35%) (158).

Prevention of pertussis transmission in health-care settings involves diagnosis and early treatment of clinical cases, respiratory isolation of infectious patients who are hospitalized, exclusion from work of staff who are infectious, and postexposure prophylaxis. Early diagnosis of pertussis, before secondary transmission occurs, is difficult because the disease is highly communicable during the catarrhal stage, when symptoms are still nonspecific. Pertussis should be one of the differential diagnoses for any patient with an acute cough illness of greater than or equal to 7 days duration without another apparent cause, particularly if characterized by paroxysms of coughing, posttussive vomiting, whoop, or apnea. Nasopharyngeal cultures should be obtained if possible.

Precautions to prevent respiratory droplet transmission or spread by close or direct contact should be employed in the care of patients admitted to hospital with suspected or confirmed pertussis (95). These precautions should remain in effect until patients are clinically improved and have completed at least 5 days of appropriate antimicrobial therapy. HCWs in whom symptoms (i.e., unexplained rhinitis or acute cough) develop after known pertussis exposure may be at risk for transmitting pertussis and should be excluded from work (16)(see Other Considerations in Vaccination of Health-Care Workers -- Work Restrictions for Susceptible Workers After Exposure).

One acellular pertussis vaccine is immunogenic in adults, but does not increase risk for adverse events when administered with tetanus and diphtheria (Td) toxoids, as compared with administration of Td alone (160). Recommendations for use of licensed diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccines among infants and young children have been published (161). If acellular pertussis vaccines are licensed for use in adults in the future, booster doses of adult formulations of acellular pertussis vaccines may be recommended to prevent the occurrence and spread of the disease in adults, including HCWs. However, acellular pertussis vaccines combined with diphtheria and tetanus toxoids (DTaP) will need to be reformulated for use in adults, because all infant formulations contain more diphtheria toxoid than is recommended for persons aged greater than or equal to 7 years. Recommendations regarding routine vaccination of adults will require additional studies (e.g., studies of the incidence, severity, and cost of pertussis among adults; studies of the efficacy and safety of adult formulations of DTaP; and studies of the effectiveness and cost-effectiveness of a strategy of adult vaccination, particularly for HCWs).

Typhoid

The incidence of typhoid fever declined steadily in the United States from 1900 to 1960 and has remained at a low level. During 1985-1994, the average number of cases reported annually was 441 (CDC, unpublished data). The median age of persons with cases of typhoid was 24 years; 53% were male. Nearly three quarters of patients infected with Salmonella typhi reported foreign travel during the 30 days before onset of symptoms. During this ten year period, several cases of laboratory-acquired typhoid fever were reported among microbiology laboratory workers, only one of whom had been vaccinated (162). S. typhi and other enteric pathogens may be nosocomially transmitted via the hands of personnel who are infected. Generally, personal hygiene, particularly hand washing before and after all patient contacts, will minimize risk for transmitting enteric pathogens to patients. If HCWs contract an acute diarrheal illness accompanied by fever, cramps, or bloody stools, they are likely to be excreting large numbers of infective organisms in their feces. Excluding these workers from care of patients until the illness has been evaluated and treated will prevent transmission (16).

Vaccinia

Vaccinia (smallpox) vaccine is a highly effective immunizing agent that brought about the global eradication of smallpox. In 1976, routine vaccinia vaccination of HCWs in the United States was discontinued. More recently, ACIP recommended use of vaccinia vaccine to protect laboratory workers from orthopoxvirus infection (10). Because studies of recombinant vaccinia virus vaccines have advanced to the stage of clinical trials, some physicians and nurses may now be exposed to vaccinia and recombinant vaccinia viruses. Vaccinia vaccination of these persons should be considered in selected instances (e.g., for HCWs who have direct contact with contaminated dressings or other infectious material).

Other Vaccine-Preventable Diseases

HCWs are not at greater risk for diphtheria, tetanus, and pneumococcal disease than the general population. ACIP recommends that all adults be protected against diphtheria and tetanus, and recommends pneumococcal vaccination of all persons aged greater than or equal to 65 years and of younger persons who have certain medical conditions (see Recommendations).

Immunizing Immunocompromised Health-Care Workers

A physician must assess the degree to which an individual health-care worker is immunocompromised. Severe immunosuppression can be the result of congenital immunodeficiency; HIV infection; leukemia; lymphoma; generalized malignancy; or therapy with alkylating agents, antimetabolites, radiation, or large amounts of corticosteroids. All persons affected by some of these conditions are severely immunocompromised, whereas for other conditions (e.g., HIV infection), disease progression or treatment stage determine the degree of immunocompromise. A determination that an HCW is severely immunocompromised ultimately must be made by his or her physician. Immunocompromised HCWs and their physicians should consider the risk for exposure to a vaccine-preventable disease together with the risks and benefits of vaccination.

Corticosteroid Therapy

The exact amount of systemically absorbed corticosteroids and the duration of administration needed to suppress the immune system of an otherwise healthy person are not well defined. Most experts agree that steroid therapy usually does not contraindicate administration of live virus vaccines such as MMR and its component vaccines when therapy is a) short term (i.e., less than 14 days) low to moderate dose; b) low to moderate dose administered daily or on alternate days; c) long-term alternate day treatment with short-acting preparations; d) maintenance physiologic doses (replacement therapy); or e) administered topically (skin or eyes), by aerosol, or by intra-articular, bursal, or tendon injection. Although the immunosuppressive effects of steroid treatment vary, many clinicians consider a steroid dose that is equivalent to or greater than a prednisone dose of 20 mg per day sufficiently immunosuppressive to cause concern about the safety of administering live virus vaccines. Persons who have received systemic corticosteroids in excess of this dose daily or on alternate days for an interval of greater than or equal to 14 days should avoid vaccination with MMR and its component vaccines for at least 1 month after cessation of steroid therapy. Persons who have received prolonged or extensive topical, aerosol, or other local corticosteroid therapy that causes clinical or laboratory evidence of systemic immunosuppression also should not receive MMR, its component vaccines, and varicella vaccine for at least 1 month after cessation of therapy. Persons who receive corticosteroid doses equivalent to greater than or equal to 20 mg per day or prednisone during an interval of less than 14 days generally can receive MMR or its component vaccines immediately after cessation of treatment, although some experts prefer waiting until 2 weeks after completion of therapy. Persons who have a disease that, in itself, suppresses the immune response and who are also receiving either systemic or locally administered corticosteroids generally should not receive MMR, its component vaccines, or varicella vaccine.

HIV-Infected Persons

In general, symptomatic HIV-infected persons have suboptimal immunologic responses to vaccines (163-167). The response to both live and killed antigens may decrease as the disease progresses (167). Administration of higher doses of vaccine or more frequent boosters to HIV-infected persons may be considered. However, because neither the initial immune response to higher doses of vaccine nor the persistence of antibody in HIV-infected patients has been systematically evaluated, recommendations cannot be made at this time.

Limited studies of MMR immunization in both asymptomatic and symptomatic HIV-infected patients who did not have evidence of severe immunosuppression documented no serious or unusual adverse events after vaccination (168). HIV-infected persons are at increased risk for severe complications if infected with measles. Therefore, MMR vaccine is recommended for all asymptomatic HIV-infected HCWs who do not have evidence of severe immunosuppression. Administration of MMR to HIV-infected HCWs who are symptomatic but do not have evidence of severe immunosuppression also should be considered. However, measles vaccine is not recommended for HIV-infected persons who have evidence of severe immunosuppression because

1. a case of progressive measles pneumonia has been reported after administration of MMR vaccine to a person with AIDS and severe immunosuppression (169), b) the incidence of measles in the United States is currently very low (17), c) vaccination-related morbidity has been reported in severely immunocompromised persons who were not HIV-infected (171), and d) a diminished antibody response to measles vaccination occurs among severely immunocompromised HIV-infected persons (172).

RECOMMENDATIONS

Recommendations for administration of vaccines and other immunobiologic agents to HCWs are organized in three broad disease categories:

• those for which active immunization is strongly recommended because of special risks for HCWs (i.e., hepatitis B, influenza, measles, mumps, rubella, and varicella);

• those for which active and/or passive immunization of HCWs may be indicated in certain circumstances (i.e., tuberculosis, hepatitis A, meningococcal disease, typhoid fever, and vaccinia) or in the future (i.e.,pertussis); and

• those for which immunization of all adults is recommended (i.e., tetanus, diphtheria, and pneumococcal disease).

Immunization Is Strongly Recommended

ACIP strongly recommends that all HCWs be vaccinated against (or have documented immunity to) hepatitis B, influenza, measles, mumps, rubella, and varicella (Table_2). Specific recommendations for use of vaccines and other immunobiologics to prevent these diseases among HCWs follow.

Hepatitis B

Any HCW who performs tasks involving contact with blood, blood-contaminated body fluids, other body fluids, or sharps should be vaccinated. Hepatitis B vaccine should always be administered by the intramuscular route in the deltoid muscle with a needle 1-1.5 inches long.

Among health-care professionals, risks for percutaneous and permucosal exposures to blood vary during the training and working career of each person but are often highest during the professional training period. Therefore, vaccination should be completed during training in schools of medicine, dentistry, nursing, laboratory technology, and other allied health professions, before trainees have contact with blood. In addition, the OSHA Federal Standard requires employers to offer hepatitis B vaccine free of charge to employees who are occupationally exposed to blood or other potentially infectious materials (27).

Prevaccination serologic screening for previous infection is not indicated for persons being vaccinated because of occupational risk unless the hospital or health-care organization considers screening cost-effective. Postexposure prophylaxis with hepatitis B immune globulin (HBIG) (passive immunization) and/or vaccine (active immunization) should be used when indicated (e.g., after percutaneous or mucous membrane exposure to blood known or suspected to be HBsAg-positive {Table_3}).

Needlestick or other percutaneous exposures of unvaccinated persons should lead to initiation of the hepatitis B vaccine series. Postexposure prophylaxis should be considered for any percutaneous, ocular, or mucous membrane exposure to blood in the workplace and is determined by the HBsAg status of the source and the vaccination and vaccine-response status of the exposed person (Table_3)(1,18).

If the source of exposure is HBsAg-positive and the exposed person is unvaccinated, HBIG also should be administered as soon as possible after exposure (preferably within 24 hours) and the vaccine series started. The effectiveness of HBIG when administered greater than 7 days after percutaneous or permucosal exposures is unknown. If the exposed person had an adequate antibody response (greater than or equal to 10 mIU/mL) documented after vaccination, no testing or treatment is needed, although administration of a booster dose of vaccine can be considered.

One to 2 months after completion of the 3-dose vaccination series, HCWs who have contact with patients or blood and are at ongoing risk for injuries with sharp instruments or needlesticks should be tested for antibody to hepatitis B surface antigen (anti-HBs). Persons who do not respond to the primary vaccine series should complete a second three-dose vaccine series or be evaluated to determine if they are HBsAg-positive. Revaccinated persons should be retested at the completion of the second vaccine series. Persons who prove to be HBsAg-positive should be counseled accordingly (1,16,121,173). Primary non-responders to vaccination who are HBsAg-negative should be considered susceptible to HBV infection and should be counseled regarding precautions to prevent HBV infection and the need to obtain HBIG prophylaxis for any known or probable parenteral exposure to HBsAg-positive blood (Table_3). Booster doses of hepatitis B vaccine are not considered necessary, and periodic serologic testing to monitor antibody concentrations after completion of the vaccine series is not recommended.

Influenza

To reduce staff illnesses and absenteeism during the influenza season and to reduce the spread of influenza to and from workers and patients, the following HCWs should be vaccinated in the fall of each year:

• Persons who attend patients at high risk for complications of influenza (whether the care is provided at home or in a health-care facility) (3);

• Persons aged greater than or equal to 65 years; and

• Persons with certain chronic medical conditions (e.g., persons who have chronic disorders of the cardiovascular or pulmonary systems; persons who required medical follow-up or hospitalization within the preceding year because of chronic metabolic disease {including diabetes}, renal dysfunction, hemoglobinopathies, or immunosuppression {including HIV infection}).

• Pregnant women who will be in the second or third trimester of pregnancy during influenza season.

Measles, Mumps, and Rubella

Persons who work within medical facilities should be immune to measles and rubella. Immunity to mumps is highly desirable for all HCWs. Because any HCW (i.e., medical or nonmedical, paid or volunteer, full time or part time, student or nonstudent, with or without patient-care responsibilities) who is susceptible can, if exposed, contract and transmit measles or rubella, all medical institutions (e.g., inpatient and outpatient, public and private) should ensure that those who work within their facilities * are immune to measles and rubella. Likewise, HCWs have a responsibility to avoid causing harm to patients by preventing transmission of these diseases.

Persons born in 1957 or later can be considered immune to measles, mumps, or rubella ** only if they have documentation of a) physician-diagnosed measles or mumps disease; or b) laboratory evidence of measles, mumps, or rubella immunity (persons who have an "indeterminate" level of immunity upon testing should be considered nonimmune); or c) appropriate vaccination against measles, mumps, and rubella (i.e., administration on or after the first birthday of two doses of live measles vaccine separated by greater than or equal to 28 days, at least one dose of live mumps vaccine, and at least one dose of live rubella vaccine).

Although birth before 1957 generally is considered acceptable evidence of measles and rubella immunity, health-care facilities should consider recommending a dose of MMR vaccine to unvaccinated workers born before 1957 who are in either of the following categories: a) those who do not have a history of measles disease or laboratory evidence of measles immunity, and b) those who lack laboratory evidence of rubella immunity. Rubella vaccination or laboratory evidence of rubella immunity is particularly important for female HCWs born before 1957 who can become pregnant.

Serologic screening need not be done before vaccinating against measles and rubella unless the health-care facility considers it cost-effective (174-176). Serologic testing is not necessary for persons who have documentation of appropriate vaccination or other acceptable evidence of immunity to measles and rubella. Serologic testing before vaccination is appropriate only if tested persons identified as nonimmune are subsequently vaccinated in a timely manner, and should not be done if the return and timely vaccination of those screened cannot be ensured (176). Likewise, during outbreaks of measles, rubella, or mumps, serologic screening before vaccination is not recommended because rapid vaccination is necessary to halt disease transmission.

Measles-mumps-rubella (MMR) trivalent vaccine is the vaccine of choice. If the recipient has acceptable evidence of immunity to one or more of the components, monovalent or bivalent vaccines may be used. MMR or its component vaccines should not be administered to women known to be pregnant. For theoretical reasons, a risk to the fetus from administration of live virus vaccines cannot be excluded. Therefore, women should be counseled to avoid pregnancy for 30 days after administration of monovalent measles or mumps vaccines and for 3 months after administration of MMR or other rubella-containing vaccines. Routine precautions for vaccinating postpubertal women with MMR or its component vaccines include a) asking if they are or may be pregnant, b) not vaccinating those who say they are or may be pregnant, and c) vaccinating those who state that they are not pregnant after the potential risk to the fetus is explained. If a pregnant woman is vaccinated or if a woman becomes pregnant within 3 months after vaccination, she should be counseled about the theoretical basis of concern for the fetus, but MMR vaccination during pregnancy should not ordinarily be a reason to consider termination of pregnancy. Rubella-susceptible women from whom vaccine is withheld because they state they are or may be pregnant should be counseled about the potential risk for congenital rubella syndrome and the importance of being vaccinated as soon as they are no longer pregnant. Measles vaccine is not recommended for HIV-infected persons with evidence of severe immunosuppression (see Vaccination of HIV-Infected Persons).

Varicella

All HCWs should ensure that they are immune to varicella. Varicella immunization is particularly recommended for susceptible HCWs who have close contact with persons at high risk for serious complications, including a) premature infants born to susceptible mothers, b) infants who are born at less than 28 weeks of gestation or who weigh less than or equal to 1,000 g at birth (regardless of maternal immune status), c) pregnant women, and d) immunocompromised persons.

Serologic screening for varicella immunity need not be done before vaccinating unless the health-care institution considers it cost-effective. Routine postvaccination testing of HCWs for antibodies to varicella is not recommended because greater than or equal to 90% of vaccinees are seropositive after the second dose of vaccine.

Hospitals should develop guidelines for management of vaccinated HCWs who are exposed to natural varicella. Seroconversion after varicella vaccination does not always result in full protection against disease. Therefore, the following measures should be considered for HCWs who are exposed to natural varicella: a) serologic testing for varicella antibody immediately after VZV exposure; b) retesting 5-6 days later to determine if an anamnestic response is present; and c) possible furlough or reassignment of personnel who do not have detectable varicella antibody. Whether postexposure vaccination protects adults is not known.

Hospitals also should develop guidelines for managing HCWs after varicella vaccination because of the risk for transmission of vaccine virus. Institutions may wish to consider precautions for personnel in whom a rash develops after vaccination and for other vaccinated HCWs who will have contact with susceptible persons at high risk for serious complications.

Hepatitis C and Other Parenterally Transmitted Non-A, Non-B Hepatitis

No vaccine or other immunoprophylactic measures are available for hepatitis C or other parenterally transmitted non-A, non-B hepatitis. HCWs should follow recommended practices for preventing transmission of all blood borne pathogens (see Background -- Hepatitis C and other Parenterally Transmitted Non-A, Non-B Hepatitis).

Other Diseases for Which Immunoprophylaxis Is or May Be Indicated

ACIP does not recommend routine immunization of HCWs against tuberculosis, hepatitis A, pertussis, meningococcal disease, typhoid fever, or vaccinia. However, immunoprophylaxis for these diseases may be indicated for HCWs in certain circumstances.

Tuberculosis and BCG Vaccination of Health-Care Workers in High-Risk Settings

BCG vaccination of HCWs should be considered on an individual basis in health-care settings where all of the following conditions are met:

• a high percentage of TB patients are infected with M. tuberculosis strains that are resistant to both isoniazid and rifampin; and

• transmission of such drug-resistant M. tuberculosis strains to HCWs is likely; and,

• comprehensive TB infection-control precautions have been implemented and have not been successful.

Vaccination with BCG should not be required for employment or for assignment in specific work areas.

BCG is not recommended for use in HIV-infected persons or persons who are otherwise immunocompromised. In health-care settings where there is a high risk for transmission of M. tuberculosis strains resistant to both isoniazid and rifampin, employees and volunteers who are infected with HIV or are otherwise immunocompromised should be fully informed about the risk for acquiring TB infection and disease and the even greater risk for development of active TB disease associated with immunosuppression.

HCWs considered for BCG vaccination should be counseled regarding the risks and benefits of both BCG vaccination and preventive therapy. They should be informed about the variable findings of research regarding the efficacy of BCG vaccination, the interference of BCG vaccination with diagnosis of newly acquired M. tuberculosis infection, and the possible serious complications of BCG vaccine in immunocompromised persons, especially those infected with HIV. They also should be informed about the lack of data regarding the efficacy of preventive therapy for M. tuberculosis infections caused by strains resistant to isoniazid and rifampin and the risks for drug toxicity associated with multidrug preventive-therapy regimens. If requested by the employee, employers should offer (but not compel) a work assignment in which an immunocompromised HCW would have the lowest possible risk for infection with M. tuberculosis.

HCWs who contract TB are a source of infection for other health-care personnel and patients. Immunocompromised persons are at increased risk for developing active disease after exposure to TB; therefore, managers of health-care facilities should develop written policies to limit activities that might result in exposure of immunocompromised employees to persons with active cases of TB.

BCG vaccination is not recommended for HCWs in low-risk settings. In most areas of the United States, most M. tuberculosis isolates (approximately 90%) are fully susceptible to isoniazid or rifampin or both, and the risk for TB transmission in health-care facilities is very low if adequate infection control practices are maintained.

Hepatitis A

Routine preexposure hepatitis A vaccination of HCWs and routine IG prophylaxis for hospital personnel providing care to patients with hepatitis A are not indicated. Rather, sound hygienic practices should be emphasized. Staff education should emphasize precautions regarding direct contact with potentially infective materials (e.g., hand washing).

In documented outbreaks of hepatitis A, administration of IG to persons who have close contact with infected patients (e.g., HCWs, other patients) is recommended. A single intramuscular dose (0.02 mL per kg) of IG is recommended as soon as possible and less than or equal to 2 weeks after exposure (2). The usefulness of hepatitis A vaccine in controlling outbreaks in health-care settings has not been investigated.

The following vaccination schedules are recommended for the vaccines available in the United States:

• HAVRIX (R): for persons aged greater than 18 years, two doses, the second administered 6-12 months after the first.

• VAQTA (R) : for persons aged greater than 17 years, two doses, the second administered 6 months after the first.

Meningococcal Disease

Routine vaccination of civilians, including HCWs, is not recommended. HCWs who have intensive contact with oropharyngeal secretions of infected patients, and who do not use proper precautions (95) should receive antimicrobial prophylaxis with rifampin (or sulfonamides, if the organisms isolated are sulfonamide-sensitive). Ciprofloxacin and ceftriaxone are reasonable alternative drugs; ceftriaxone can be administered to pregnant women. Vaccination with quadrivalent polysaccharide vaccine should be used to control outbreaks of serogroup C meningococcal disease. Surveillance for serogroup C disease and calculation of attack rates can be used to identify outbreaks and determine whether use of meningococcal vaccine is warranted.

Pertussis

Pertussis vaccines (whole-cell and acellular) are licensed for use only among children aged 6 weeks through 6 years. If acellular pertussis vaccines are licensed for use in adults in the future, booster doses of adult formulations may be recommended to prevent the occurrence and spread of the disease in HCWs.

Typhoid

Workers in microbiology laboratories who frequently work with S. typhi should be vaccinated with any one of the three typhoid vaccines distributed in the United States: oral live-attenuated Ty21a vaccine (one enteric-coated capsule taken on alternate days to a total of four capsules), the parenteral heat-phenol inactivated vaccine (two 0.5 mL subcutaneous doses, separated by greater than or equal to 4 weeks), or the capsular polysaccharide parenteral vaccine (one 0.5 mL intramuscular dose). Under conditions of continued or repeated exposure to S. typhi, booster doses are required to maintain immunity, every 5 years if the oral vaccine is used, every 3 years if the heat-phenol inactivated parenteral vaccine is used, and every 2 years if the capsular polysaccharide vaccine is used. Live-attenuated Ty21a vaccine should not be used among immunocompromised persons, including those infected with HIV (13).

Vaccinia

Vaccinia vaccine is recommended only for the few persons who work with orthopoxviruses (e.g., laboratory workers who directly handle cultures or animals contaminated or infected with vaccinia, recombinant vaccinia viruses, or other orthopoxviruses that replicate readily in humans {e.g., monkeypox, cowpox, and others}). Other HCWs (e.g., physicians and nurses) whose contact with these viruses is limited to contaminated materials (e.g., dressings) and who adhere to appropriate infection control measures are at lower risk for accidental infection than laboratory workers, but may be considered for vaccination. When indicated, vaccinia vaccine should be administered every 10 years (10). Vaccinia vaccine should not be administered to immunocompromised persons (including persons infected with HIV), persons who have eczema or a history of eczema, or to pregnant women (10).

Other Vaccine-Preventable Diseases

Health-care workers are not at substantially increased risk than the general adult population for acquiring diphtheria, pneumococcal disease, or tetanus. Therefore, they should seek these immunizations from their primary care provider, according to ACIP recommendations (12,14).

Tetanus and Diphtheria

Primary vaccination of previously unvaccinated adults consists of three doses of adult tetanus-diphtheria toxoid (Td): 4-6 weeks should separate the first and second doses; the third dose should be administered 6-12 months after the second (12). After primary vaccination, a tetanus-diphtheria (Td) booster is recommended for all persons every 10 years. HCWs should be encouraged to receive recommended Td booster doses.

Pneumococcal Disease

Persons for whom pneumococcal vaccine is recommended include:

• Persons aged greater than or equal to 65 years.

• Persons aged greater than or equal to 2 and less than 65 years who, because they have certain chronic illnesses, are at increased risk for pneumococcal disease, its complications, or severe disease if they become infected. Included are those who have chronic cardiovascular disease (i.e., congestive heart failure {CHF} or cardiomyopathies), chronic pulmonary disease (i.e., chronic obstructive pulmonary disease {COPD} or emphysema, but not asthma), diabetes mellitus, alcoholism, chronic liver disease (cirrhosis), or cerebrospinal fluid leaks.

• Persons greater than or equal to 2 and less than 65 years of age with functional or anatomic asplenia (e.g., sickle cell disease, splenectomy).

• Persons greater than or equal to 2 and less than 65 years of age living in special environments or social settings where an increased risk exists for invasive pneumococcal disease or its complications (e.g., Alaska Natives and certain American Indian populations).

• Immunocompromised persons greater than or equal to 2 years of age, including

1. persons infected with HIV and persons who have leukemia, lymphoma, Hodgkin's disease, multiple myeloma, generalized malignancy, chronic renal failure, nephrotic syndrome;

2. persons with other conditions associated with immunosuppression (e.g., organ or bone marrow transplantation); and

3. persons receiving immunosuppressive chemotherapy, including long-term systemic corticosteroids.

Immunization of Immunocompromised Health-Care Workers

ACIP has published recommendations for immunization of immunocompromised persons (177). ACIP recommendations for use of individual vaccines or immune globulins also should be consulted for additional information regarding the epidemiology of the diseases and the safety and the efficacy of the vaccines or immune globulin preparations. Specific recommendations for use of vaccines depend upon the type of immunocompromising condition (Table_4).

Killed or inactivated vaccines do not represent a danger to immunocompromised HCWs and generally should be administered as recommended for workers who are not immunocompromised. Additional vaccines, particularly bacterial polysaccharide vaccines (i.e., Haemophilus influenzae type b {Hib} vaccine, pneumococcal vaccine, and meningococcal vaccine), are recommended for persons whose immune function is compromised by anatomic or functional asplenia and certain other conditions. Frequently, the immune response of immunocompromised persons to these vaccine antigens is not as good as that of nonimmunocompromised persons; higher doses or more frequent boosters may be required. Even with these modifications, the immune response may be suboptimal.

HIV-Infected Persons

Specific recommendations for vaccination of HIV-infected persons have been developed (Table_4). In general, live virus or live bacterial vaccines should not be administered to HIV-infected persons. However, asymptomatic HCWs need not be tested for HIV infection before administering live virus vaccines.

The following recommendations apply to all HCWs infected with HIV:

• MMR vaccine is recommended for all asymptomatic HIV-infected HCWs who do not have evidence of severe immunosuppression. Administration of MMR to HIV-infected HCWs who are symptomatic, but who do not have evidence of severe immunosuppression, should be considered. Measles vaccine is not recommended for HIV-infected persons with evidence of severe immunosuppression.

• Enhanced inactivated poliovirus vaccine (IPV) is the only poliovirus vaccine recommended for HIV-infected persons (11). Live oral poliovirus vaccine (OPV) should not be administered to immunocompromised persons.

• Influenza and pneumococcal vaccines are indicated for all HIV-infected persons (influenza vaccination for persons aged greater than or equal to 6 months and pneumococcal vaccination for persons aged greater than or equal to 2 years).

  
  

OTHER CONSIDERATIONS IN VACCINATION OF HEALTH-CARE WORKERS

Other considerations important to appropriate immunoprophylaxis of HCWs include maintenance of complete immunization records, policies for catch-up vaccination of HCWs, work restrictions for susceptible employees who are exposed to vaccine-preventable diseases, and control of outbreaks of vaccine-preventable disease in health-care settings. Additional vaccines not routinely recommended for HCWs in the United States may be indicated for those who travel to certain other regions of the world to perform research or health-care work (e.g., as medical volunteers in a humanitarian effort).

Immunization Records

An immunization record should be maintained for each HCW. The record should reflect documented disease and vaccination histories as well as immunizing agents administered during employment. At each immunization encounter, the record should be updated and the HCW encouraged to maintain the record as appropriate (15).

Catch-Up Vaccination Programs

Managers of health-care facilities should consider implementing catch-up vaccination programs for HCWs who are already employed, in addition to policies to ensure that newly hired HCWs receive necessary vaccinations. This strategy will help prevent outbreaks of vaccine preventable diseases (see Outbreak Control). Because education enhances the success of many immunization programs, reference materials should be available to assist in answering questions regarding the diseases, vaccines, and toxoids, and the program or policy being implemented. Conducting educational workshops or seminars several weeks before the initiation of the program may be necessary to ensure acceptance of program goals.

Work Restrictions for Susceptible Workers After Exposure

Postexposure work restrictions ranging from restriction of contact with high-risk patients to complete exclusion from duty are appropriate for HCWs who are not immune to certain vaccine-preventable diseases (Table_5). Recommendations concerning work restrictions in these circumstances have been published (16,35,178).

Outbreak Control

Hospitals should develop comprehensive policies and protocols for management and control of outbreaks of vaccine-preventable disease. Outbreaks of vaccine-preventable diseases are costly and disruptive. Outbreak prevention, by ensuring that all HCWs who have direct contact with patients are fully immunized, is the most effective and cost-effective control strategy. Disease-specific outbreak control measures are described in published ACIP recommendations (Table_1) (1-15) and infection control references (16,35,95, 178-180).

Vaccines Indicated for Foreign Travel

Hospital and other HCWs who perform research or health-care work in foreign countries may be at increased risk for acquiring certain diseases (e.g, hepatitis A, poliomyelitis, Japanese encephalitis, meningococcal disease, plague, rabies, typhoid, or yellow fever). Vaccinations against those diseases should be considered when indicated for foreign travel (181). Elevated risks for acquiring these diseases may stem from exposure to patients in health-care settings (e.g., poliomyelitis, meningococcal disease), but may also arise from circumstances unrelated to patient care (e.g, high endemicity of hepatitis A or exposure to arthropod disease vectors {yellow fever}).

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27. Department of Labor. Bloodborne pathogens: the standard. Federal Register 1991;60:64175-82.

28. Stevens CE, Toy PT, Taylor PE, Lee T, Yip H-Y. Prospects for control of hepatitis B virus infection: implications of childhood vaccination and long-term protection. Pediatrics 1992;90:170-3.

29. Hadler SC, Margolis HS. Hepatitis B immunization: vaccine types, efficacy, and indications for immunization. In Remington JS, Swartz MN: Current topics in infectious diseases. Boston: Blackwell Scientific, 1992:282-308.

30. Balkovic ES, Goodman RA, Rose FB, et al. Nosocomial influenza A(H1N1) infection. Am J Med Technol 1980;46:318-20.

31. Van Voris LP, Belshe RB, Shaffer JL. Nosocomial influenza B virus infection in the elderly. Ann Intern Med 1982;96:153-8.

32. CDC. Suspected nosocomial influenza cases in an intensive care unit. MMWR 1988;37:3.

33. Pachucki CT, Walsh Pappas SA, Fuller GF, Krause SL, Lentino JR, Schaaf DM. Influenza A among hospital personnel and patients: implications for recognition, prevention, and control. Arch Intern Med 1990;149: 77-80.

34. Hammond GW, Cheang M. Absenteeism among hospital staff during an influenza epidemic: Implications for immunoprophylaxis. Can Med Assoc J 1984;131:449-52.

35. Williams WW, Preblud SR, Reichelderfer PS, Hadler SC. Vaccines of importance in the hospital setting. Infect Dis Clin North Am 1989;3:701-22.

36. Mast EE, Harmon MW, Gravenstein S, et al. Emergence and possible transmission of amantadine-resistant viruses during nursing home outbreaks of influenza (AH3N2). Am J Epidemiol. 1991;134:986-97.

37. Horman JT, Stetler HC, Israel E, Sorley D, Schipper MT, Joseph JM. An outbreak of influenza A in a nursing home. Am J Public Health 1986;76:501-4.

38. Patriarca PA, Weber JA, Parker RA, et al. Risk factors for outbreaks of influenza in nursing homes: a case-control study. Am J Epidemiol 1986;124:114-9.

39. CDC. Outbreak of influenza A in a nursing home -- New York, December, 1991-January, 1992. MMWR 1992;41:129-31.

40. Gross PA, Rodstein M, LaMontagne JR, et al. Epidemiology of acute respiratory illness during an influenza outbreak in a nursing home. Arch Intern Med 1988;148:559-61.

41. Cartter ML, Renzullo PO, Helgerson SD, Martin SM, Jekel JF. Influenza outbreaks in nursing homes: how effective is influenza vaccine in the institutionalized elderly? Infect Control Hosp Epidemiol 1990;11: 473-8.

42. Potter J, Stott DJ, Roberts MA, et al. Influenza vaccination of health care workers in long-term-care hospitals reduces the mortality of elderly patients. J Infect Dis 1997;175:1-6.

43. CDC. Measles in HIV-infected children -- United States. MMWR 1988;37: 183-6.

44. CDC. Measles transmitted in a medical office building -- New Mexico, 1986. MMWR 1987;36:25-7.

45. Davis RM, Orenstein WA, Frank Jr, JA, et al. Transmission of measles in medical settings, 1980 through 1984. JAMA 1986;255:1295-8.

46. Istre GR, KcKee PA, West GR, et al. Measles spread in medical settings: an important focus of disease transmission? Pediatrics 1987;79:356-8.

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48. Watkins NM, Smith Jr RP, St.Germain DL, et al. Measles (rubeola) infection in a hospital setting. Am J Infect Control 1987;15:201-6.

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56. Kaplan KM, Marder DC, Cochi SL, et al. Mumps in the workplace: further evidence of the changing epidemiology of a childhood vaccine-preventable disease. JAMA 1988;260:1434-8.

57. CDC. Mumps outbreaks on university campuses -- Illinois, Wisconsin, South Dakota, MMWR 1987;36:496-498,503-5.

58. Sosin DM, Cochi SL, Gunn RA, et al. Changing epidemiology of mumps and its impact on university campuses. Pediatrics 1989;84:779-84.

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116. Valway SE, Greifinger RB, Papania M, et al. Multidrug-resistant tuberculosis in the New York State prison system, 1990-1991. J Infect Dis 1994;170:151-6.

117. Alter MJ, Margolis HS, Krawczynski K, et al. The natural history of community-acquired hepatitis C in the United States. N Engl J Med 1992;327:1899-905.

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121. CDC. Public Health Service inter-agency guidelines for screening donors of blood, plasma, organs, tissues, and semen for evidence of hepatitis B and hepatitis C. MMWR 1991;40(RR-4):1-17.

122. Leslie M, Damen HTM, Cuypers HL, et al. International collaborative study on the second Eurohep HCV-RNA reference panel. In:Proceedings of the IX International Symposium on Viral Hepatitis and Liver Disease. Rome, 1996: 25.

123. Alter MJ, Gerety RJ, Smallwood L, et al. Sporadic non-A, non-B hepatitis: frequency and epidemiology in an urban United States population. J Infect Dis 1982;145:886-93.

124. Seeff LB. Hepatitis C from a needlestick injury {letter}. Ann Intern Med 1991;115:411.

125. Cooper BW, Krusell A, Tilton RC, Goodwin R, Levitz RE. Seroprevalence of antibodies to hepatitis C virus in high-risk hospital personnel. Infect Control Hosp Epidemiol 1992;13:82-5.

126. Campello C, Majori S, Poli A, Pacini P, Nicolardi L, Pini F. Prevalence of HCV antibodies in health-care workers from northern Italy. Infection 1992;20:224-6.

127. Polish LB, Tong MJ, Co RL, Coleman PJ, Alter MJ. Risk factors for hepatitis C virus infection among health care personnel in a community hospital. Am J Infect Control 1993;21:196-200.

128. Panlilio AL, Shapiro CN, Schable CA, et al. Serosurvey of human immunodeficiency virus, hepatitis B virus, and hepatitis C virus infection among hospital-based surgeons. J Am Coll Surg 1995;180: 16-24.

129. Klein RS, Freeman K, Taylor PE, Stevens CE. Occupational risk for hepatitis C virus infection among New York City dentists. Lancet 1991; 338:1539-42.

130. Thomas DL, Gruninger SE, Siew C, Joy ED, Quinn TC. Occupational risk of hepatitis C infections among general dentists and oral surgeons in North America. Am J Med 1996;100:41-5.

131. Tsude K, Fujiyama S, Sato S, Kawano S, Taura Y, Yoshida K, Sato T. Two cases of accidental transmission of hepatitis C to medical staff. Hepatogastroenterology 1992;39:73-5.

132. Hernandez ME, Bruguera M, Puyuelo T, Barrera JM, Sanchez Tapias JM, Rodes J. Risk of needle-stick injuries in the transmission of hepatitis C virus in hospital personnel. J Hepatol 1992;16:56-8.

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135. Lanphear BP, Linnemann CC, Cannon CG, DeRonde MM, Pendy L, Kerley LM. Hepatitis C virus infection in health care workers: risk of exposure and infection. Infect Control Hosp Epidemiol 1994;15:745-50.

136. Mitsui T, Iwano K, Masuko K, et al. Hepatitis C virus infection in medical personnel after needlestick accident. Hepatology 1992;16: 1109-14.

137. Puro V, Petrosillo N, Ippolito G. Risk of hepatitis C seroconversion after occupational exposures in health care workers.Italian Study Group on Occupational Risk of HIV and Other Bloodborne Infections. Am J Infect Control 1995;23:273-7.

138. Sartori M, La Terra G, Aglietta M, et al. Transmission of hepatitis C via blood splash into conjunctiva. Scand J Infect Dis 1993;25:270-1.

139. Knodell RG, Conrad ME, Ginsburg AL, Bell CJ, Flannery EP. Efficacy of prophylactic gamma globulin in preventing non-A, non-B post-transfusion hepatitis. Lancet 1976;1:557-61.

140. Seeff LB, Zimmerman JH, Wright EL, et al. A randomized double-blind controlled trial of the efficacy of immune serum globulin for the prevention of post-transfusion hepatitis. A Veterans Administration cooperative study. Gastroenterology 1977;72:111-21.

141. Sanchez-Quijano A, Pineda JA, Lissen E, et al. Prevention of post-transfusion non-A, non-B hepatitis by non-specific immunoglobulin in heart surgery patients. Lancet 1988;1:1245-9.

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143. Krawczynski K, Alter MJ, Tankersley DL, et al. Studies on protective efficacy of hepatitis C immunoglobulins (HCIG) in experimental hepatitis C virus infection {Abstract}. Hepatology 1993;18:110A.

144. Hoofnagle JH, Di Bisceglie AM. Drug therapy: the treatment of chronic viral hepatitis. N Engl J Med 1997;336:347-56.

145. Peters M, Davis GL, Dooley JS, et al. The interferon system in acute and chronic viral hepatitis. Prog Liver Dis 1986;8:453-67.

146. CDC. Recommendations for follow-up of health-care workers after occupational exposure to hepatitis C virus. MMWR 1997;46:603-6.

147. Noble RC, Kane MA, Reeves SA, et al. Posttransfusion hepatitis A in a neonatal intensive care unit. JAMA 1984;252:2711-5.

148. Klein BS, Michaels JA, Rytel MW, Berg KG, Davis JP. Nosocomial hepatitis A: a multi-nursery outbreak in Wisconsin. JAMA 1984;252: 2716-21.

149. Rosenblum LS, Villarino ME, Nainan OV, et al. Hepatitis A outbreak in a neonatal intensive care unit: risk factors for transmission and evidence of prolonged viral excretion among preterm infants. J Infect Dis 1991;164:476-82.

150. Goodman RA. Nosocomial hepatitis A. Ann Intern Med 1985;103:452-4.

151. Papaevangelou GJ, Roumeliotou-Karayannis AJ, Contoyannis PC. The risk of hepatitis A and B virus infections from patients under care without isolation precautions. J Med Virol 1981;7:143-8.

152. Werzberger A, Mensch B, Kuter B, et al. A controlled trial of a formalin-inactivated hepatitis A vaccine in healthy children. N Engl J Med 1992;327:453-7.

153. Innis B, Snitbhan R, Kunasol P, et al. Field efficacy trial of inactivated hepatitis A vaccine among children in Thailand (an extended abstract). Vaccine 1992 10 (Suppl 1):S159.

154. Mortimer EA Jr. Pertussis Vaccine. In: Plotkin SA, Mortimer EA, eds. Vaccines, 2nd ed. Philadelphia: W.B. Saunders, 1994: 94.

155. Mortimer EA Jr. Pertussis and its prevention: a family affair. J Infect Dis 1990;161:473-9.

156. Christie C, Glover AM, Willke MJ, Marx ML, Reising SF, Hutchinson NM. Containment of pertussis in the regional pediatric hospital during the greater Cincinnati epidemic of 1993. Infect Control Hosp Epidemiol 1995;16:556-63.

157. Kurt TL, Yeager AS, Guennette S, Dunlop S. Spread of pertussis by hospital staff. JAMA 1972;221:264-7.

158. Linnemann CC, Ramundo N, Perlstein PH, et al. Use of pertussis vaccine in an epidemic involving hospital staff. Lancet 1975;2:540-3.

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177. CDC. Use of vaccines and immune globulins in persons with altered immunocompetence -- recommendations of the Advisory Committee on Immunization Practices(ACIP). MMWR 1993;42(No. RR-4):1-18.

178. Williams WW. CDC guideline for infection control in hospital personnel. Infect Control 1983;4(Suppl):326-49.

179. Fedson DS. Immunizations for health care workers and patients in hospitals. In: Wenzel RP, ed. Prevention and control of nosocomial infections. Baltimore: Williams & Wilkins, 1992: 214-94.

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* A possible exception might be an outpatient facility that deals exclusively with elderly patients considered at low risk for measles.

** Birth before 1957 is not acceptable evidence of rubella immunity for women who can become pregnant because rubella can occur in some unvaccinated persons born before 1957 and because congenital rubella syndrome can occur in offspring of women infected with rubella during pregnancy.
Table_1
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TABLE 1. Recommendations for immunization practices and use of immunobiologics
applicable to disease prevention among health-care workers -- Advisory Committee
on Immunization Practices (ACIP) statements published as of September 1, 1997
=================================================================================================
Subject                                     MMWR Publication
-------------------------------------------------------------------
General recommendations on immunization     1994;43(No.RR-1):1-39

Adult immunization                          1991;40(No.RR-12):1-94

Altered immunocompetence                    1993;42(No.RR-4):1-18

Adverse reactions, contraindications, and
  precautions                               1996;45(No.RR-12):1-35

Bacille Calmette-Guerin vaccine             1996;45(No.RR-4):1-18

Diphtheria, tetanus, and pertussis          1991;40(No.RR-10):1-28
                                            1997;46(No. RR-7)

Hepatitis B                                 1991;40(No.RR-13):1-25

Hepatitis A                                 1996;45(No.RR-15):1-30

Influenza *                                 1997;46(No.RR-9):1-25

Japanese encephalitis                       1993;42(No.RR-1):1-15

Measles                                     1989;38(No.S9):1-18

Measles, mumps, rubella (MMR)               1998;47 (in press)

Meningococcal disease and outbreaks         1997;46(No.RR-5):1-21

Mumps                                       1989;38:388-92, 397-400
 (MMR in press, see Measles above)

Pertussis, acellular                        1992;41(No.RR-1):1-10
 (see also Diphtheria above)                1992;41(No.RR-15):1-5
 (supplementary statements)                 1997;46(No.RR-7):1-25

Pneumococcal                                1997;46(No.RR-8):1-24

Poliomyelitis                               1997;46(No.RR-3):1-25

Rabies                                      1991;40(No.RR-3):1-19

Rubella                                     1990;39(No.RR-15):1-18
 (MMR in press, see Measles above)

Typhoid                                     1994;43(No.RR-14):1-7

Vaccinia (smallpox)                         1991;40(No.RR-14):1-10

Varicella                                   1996;45(No.RR-11):1-36
-------------------------------------------------------------------
* Each year influenza vaccine recommendations are reviewed and amended to reflect updated
  information concerning influenza activity in the United States for the preceding influenza
  season and to provide information on the vaccine available for the upcoming influenza season.
  These recommendations are published annually in the MMWR, usually during May or June.
=================================================================================================

TABLE 2. Immunizing agents and immunization schedules for health-care workers (HCWs)*
===============================================================================================================================================================
                          Primary schedule and                                              Major precautions and
Generic name              booster(s)                   Indications                          contraindications                 Special considerations
-------------------------------------------------------------------------------------------------------------------------------------------------------------
IMMUNIZING AGENTS STRONGLY RECOMMENDED FOR HEALTH-CARE WORKERS

Hepatitis B (HB)          Two doses IM 4 weeks         Preexposure: HCWs at risk            On the basis of limited data,     The vaccine produces neither
recombinant               apart; third dose 5          for exposure to blood or             no risk of adverse effects to     therapeutic nor adverse
vaccine                   months after second;         body fluids.                         developing fetuses is             effects on HBV-infected
                          booster doses not            Postexposure: See Table 3.           apparent. Pregnancy should        persons. Prevaccination
                          necessary.                                                        not be considered a               serologic screening is not
                                                                                            contraindication to               indicated for persons being
                                                                                            vaccination of women.             vaccinated because of
                                                                                            Previous anaphylactic             occupational risk. HCWs who
                                                                                            reaction to common baker's        have contact with patients or
                                                                                            yeast is a contraindication to    blood should be tested 1-2
                                                                                            vaccination.                      months after vaccination to
    determine serologic
    response.

Hepatitis B immune        0.06 mL/kg IM as soon        Postexposure prophylaxis
globulin (HBIG)           as possible after            (Table 3): For persons
                          exposure. A second           exposed to blood or body
                          dose of HBIG should          fluids containing HBsAg and
                          be administered 1            who are not immune to HBV
                          month later if the HB        infection -- 0.06 mL/kg IM as
                          vaccine series has not       soon as possible (but no later
                          been started.                than 7 days after exposure).

Influenza vaccine         Annual vaccination           HCWs who have contact with           History of anaphylactic           No evidence exists of risk to
(inactivated              with current vaccine.        patients at high risk for            hypersensitivity to egg           mother or fetus when the
whole-virus and           Administered IM.             influenza or its                     ingestion.                        vaccine is administered to a
split-virus vaccines)                                  complications; HCWs who                                                pregnant woman with an
                                                       work in chronic care facilities;                                       underlying high-risk
                                                       HCWs with high-risk medical                                            condition. Influenza
                                                       conditions or who are aged                                             vaccination is recommended
                                                       >=65 years.                                                            during second and third
    trimesters of pregnancy
    because of increased risk for
    hospitalization.

Measles live-virus        One dose SC; second          HCWs + born during or after          Pregnancy;                        MMR is the vaccine of choice
vaccine                   dose at least 1 month        1957 who do not have                 immunocompromised                 if recipients are likely to be
                          later.                       documentation of having              persons &., including             susceptible to rubella and/or
                                                       received 2 doses of live             HIV-infected persons who          mumps as well as to
                                                       vaccine on of after the first        have evidence of severe           measles. Persons vaccinated
                                                       birthday or a history of             immunosuppression;                during 1963-1967 with a
                                                       physician-diagnosed measles          anaphylaxis after gelatin         killed measles vaccine alone,
                                                       or serologic evidence of             ingestion or administration       killed vaccine followed by
                                                       immunity.                            of neomycin; recent               live vaccine, or with a
                                                       Vaccination should be                administration of immune          vaccine of unknown type
                                                       considered for all HCWs who          globulin.                         should be revaccinated with
                                                       lack proof of immunity,                                                2 doses of live measles virus
                                                       including those born before                                            vaccine.
                                                       1957.

Mumps live-virus          One dose SC; no              HCWs + believed to be                Pregnancy;                        MMR is the vaccine of choice
vaccine                   booster.                     susceptible can be                   immunocompromised                 if recipients are likely to be
                                                       vaccinated. Adults born              persons &; history of             susceptible to measles and
                                                       before 1957 can be                   anaphylactic reaction after       rubella as well as to mumps.
                                                       considered immune.                   gelatin ingestion or
                                                                                            administration of neomycin.

Rubella live-virus        One dose SC; no              Indicated for HCWs +, both           Pregnancy;                        The risk for rubella
vaccine                   booster                      men and women, who do not            immunocompromised                 vaccine-associated
                                                       have documentation of                persons +; history of             malformations in the
                                                       having received live vaccine         anaphylactic reaction after       offspring of women pregnant
                                                       on or after their first birthday     administration of neomycin.       when vaccinated or who
                                                       or laboratory evidence of                                              become pregnant within 3
                                                       immunity. Adults born before                                           months after vaccination is
                                                       1957, except women who                                                 negligible. Such women
                                                       can become pregnant, can                                               should be counseled
                                                       be considered immune.                                                  regarding the theoretical
    basis of concern for the fetus.
    MMR is the vaccine of choice
    if recipients are likely to be
    susceptible to measles or
    mumps, as well as to rubella.

Varicella zoster          Two 0.5 mL doses SC          Indicated for HCWs + who do          Pregnancy,                        Vaccine is available from the
live-virus vaccine        4-8 weeks apart if           not have either a reliable           immunocompromised                 manufacturer for certain
                          >=13 years of age.           history of varicella or              persons &, history of             patients with acute
                                                       serologic evidence of                anaphylactic reaction             lymphocytic leukemia (ALL)
                                                       immunity.                            following receipt of              in remission. Because
                                                                                            neomycin or gelatin. Avoid        71%-93% of persons without
                                                                                            salicylate use for 6 weeks        a history of varicella are
                                                                                            after vaccination.                immune, serologic testing
    before vaccination is likely to
    be cost-effective.

Varicella-zoster          Persons <50 kg:              Persons known or likely to be                                          Serologic testing may help in
immune globulin           125 u/10 kg IM;              susceptible (particularly                                              assessing whether to
(VZIG)                    persons >=50 kg:             those at high risk for                                                 administer VZIG. If use of
                          625 u @.                     complications, e.g., pregnant                                          VZIG prevents varicella
                                                       women) who have close and                                              disease, patient should be
                                                       prolonged exposure to a                                                vaccinated subsequently.
                                                       contact case or to an
                                                       infectious hospital staff
                                                       worker or patient.

BCG VACCINATION
Bacille Calmette          One percutaneous             Should be considered only            Should not be administered        In the United States
Guerin(BCG)               dose of 0.3 mL; no           for HCWs in areas where              to immunocompromised              tuberculosis-control efforts
Vaccine                   booster dose                 multi-drug tuberculosis is           persons, & pregnant women.        are directed towards early
(Tuberculosis)            recommended.                 prevalent, a strong likelihood                                         identification, treatment of
                                                       of infection exists, and where                                         cases, and preventive
                                                       comprehensive infection                                                therapy with isoniazid.
                                                       control precautions have
                                                       failed to prevent TB
                                                       transmission to HCWs.


OTHER IMMUNOBIOLOGICS THAT ARE OR MAY BE INDICATED FOR HEALTH-CARE WORKERS
-------------------------------------------------------------------------------------------------------------------------------------------------------------
                          Primary schedule and                                              Major precautions and             Special considerations
Generic name              booster(s)                   Indications                          contraindications
-------------------------------------------------------------------------------------------------------------------------------------------------------------
Immune globulin           Postexposure-One IM          Indicated for HCWs exposed           Contraindicated in persons        Administer in large muscle
(Hepatitis A)             dose of 0.02 mL/kg           to feces of infectious patients.     with IgA deficiency; do not       mass (deltoid, gluteal).
                          administered <=2 weeks                                            administer within 2 weeks
                          after exposure.                                                   after MMR vaccine, or 3
                                                                                            weeks after varicella vaccine.
                                                                                            Delay administration of MMR
                                                                                            vaccine for >=3 months and
                                                                                            varicella vaccine >=5 months
                                                                                            after administration of IG.

Hepatitis A vaccine       Two doses of vaccine         Not routinely indicated for          History of anaphylactic
                          either 6-12 months           HCWs in the United States.           hypersensitivity to alum or,
                          apart (HAVRIX (R)), or 6     Persons who work with                for HAVRIX (R), the
                          months apart (VAQTA (R)).    HAV-infected primates or             preservative
                                                       with HAV in a research               2-phenoxyethanol. The
                                                       laboratory setting should be         safety of the vaccine in
                                                       vaccinated.                          pregnant women has not
                                                                                            been determined; the risk
                                                                                            associated with vaccination
                                                                                            should be weighed against
                                                                                            the risk for hepatitis A in
                                                                                            women who may be at high
                                                                                            risk for exposure to HAV.

Meningococcal             One dose in volume           Not routinely indicated for          The safety of the vaccine in
polysaccharide            and by route specified       HCWs in the United States.           pregnant women has not
vaccine (tetravalent      by manufacturer; need                                             been evaluated; it should not
A, C, W135, and Y)        for boosters unknown.                                             be administered during
                                                                                            pregnancy unless the risk for
                                                                                            infection is high.

Typhoid vaccine,          IM vaccine: One 0.5          Workers in microbiology              Severe local or systemic          Vaccination should not be
IM, SC, and oral          mL dose, booster 0.5         laboratories who frequently          reaction to a previous dose.      considered an alternative to
                          mL every 2 years.            work with Salmonella typhi.          Ty21a (oral) vaccine should       the use of proper procedures
                          SC vaccine: two 0.5                                               not be administered to            when handling specimens
                          mL doses, >=4 weeks                                               immunocompromised                 and cultures in the laboratory.
                          apart, booster 0.5 mL                                             persons & or to persons
                          SC or 0.1 ID every 3                                              receiving antimicrobial
                          years if exposure                                                 agents.
                          continues.
                          Oral vaccine: Four
                          doses on alternate
                          days. The
                          manufacturer
                          recommends
                          revaccination with the
                          entire four-dose series
                          every 5 years.

Vaccinia vaccine          One dose                     Laboratory workers who               The vaccine is                    Vaccination may be
(smallpox)                administered with a          directly handle cultures with        contraindicated in pregnancy,     considered for HCWs who
                          bifurcated needle;           vaccinia, recombinant                in persons with eczema or a       have direct contact with
                          boosters administered        vaccinia viruses, or orthopox        history of eczema, and in         contaminated dressings or
                          every 10 years.              viruses that infect humans.          immunocompromised                 other infectious material
                                                                                            persons & and their household     from volunteers in clinical
                                                                                            contacts.                         studies involving
    recombinant vaccinia virus.


OTHER VACCINE-PREVENTABLE DISEASES

Tetanus and               Two IM doses 4 weeks         All adults.                          Except in the first trimester,    Tetanus prophylaxis in
diphtheria (toxoids       apart; third dose 6-12                                            pregnancy is not a                wound management **.
{Td})                     months after second                                               precaution. History of a
                          dose; booster every                                               neurologic reaction or
                          10 years.                                                         immediate hypersensitivity
                                                                                            reaction after a previous
                                                                                            dose. History of severe local
                                                                                            (Arthus-type) reaction after a
                                                                                            previous dose.  Such persons
                                                                                            should not receive further
                                                                                            routine or emergency doses
                                                                                            of Td for 10 years.

Pneumococcal              One dose, 0.5 mL, IM         Adults who are at increased          The safety of vaccine in
polysaccharide            or SC; revaccination         risk of pneumococcal disease         pregnant women has not
vaccine (23 valent).      recommended for              and its complications                been evaluated; it should not
                          those at highest risk        because of underlying health         be administered during
                          >=5 years after the first    conditions; older adults,            pregnancy unless the risk for
                          dose.                        especially those age >=65 who        infection is high. Previous
                                                       are healthy.                         recipients of any type of
                                                                                            pneumococcal
                                                                                            polysaccharide vaccine who
                                                                                            are at highest risk for fatal
                                                                                            infection or antibody loss
                                                                                            may be revaccinated >=5
                                                                                            years after the first dose.
-------------------------------------------------------------------------------------------------------------------------------------------------------------
 * Persons who provide health care to patients or work in institutions that provide patient care, e. g., physicians, nurses, emergency medical
   personnel, dental professionals and students, medical and nursing students, laboratory technicians, hospital volunteers, and adminis-
   trative and support staff in health-care institutions
 + All HCWs (i.e., medical or nonmedical, paid or volunteer, fulltime or part time, student or non-student, with or without patient-care
   responsibilities) who work in health-care institutions (e.g., inpatient and outpatient, public and private) should be immune to measles,
   rubella, and varicella.
 & Persons immunocompromised because of immune deficiency diseases, HIV infection (who should primarily not receive BCG, OPV, and
   yellow fever vaccines), leukemia, lymphoma or generalized malignancy or immunosuppressed as a result of therapy with corticosteroids,
   alkylating drugs, antimetabolites, or radiation.
  @ Some experts recommend 125 u/10 kg regardless of total body weight.
** See (15) CDC. Update on adult immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR
1991:40(No. RR-12):1-94.

Abbreviations: IM = intramuscular; HBV = hepatitis B virus; HBsAg = hepatitis B surface antigen; SC = subcutaneous; HIV = human
immunodeficiency virus; MMR = measles, mumps, rubella vaccine; HCW = health-care worker; TB = tuberculosis; HAV = hepatitis A
virus; IgA = immune globulin A; ID = intradermal.
===============================================================================================================================================================

TABLE 3. Recommended postexposure prophylaxis for percutaneous or permucosal
exposure to hepatitis B virus, United States
=======================================================================================================
                                                    Treatment when source is
Vaccination and anti-    ----------------------------------------------------------------------------
 body response status                                                       Source not tested or
of exposed person        HBsAG * positive           HBsAg negative           status unknown
-----------------------------------------------------------------------------------------------------
Unvaccinated             HBIG + x 1; initiate HB    Initiate HB vaccine     Initiate HB vaccine
                         vaccine series &           series                  series
Previously vaccinated:
Known responder @        No treatment               No treatment            No treatment

Known non-responder      HBIG x 2 or                No treatment            If known high-risk
                         HBIG x 1 and initiate                              source, treat as if
                         revaccination                                      source were HBsAg
                                                                            positive
Antibody response        Test exposed person        No treatment            Test exposed person
unknown                  for anti-HBs **                                    for anti-HBs
                         1. If adequate @, no                               1. If adequate @, no
                            treatment                                          treatment
                         2. If inadequate @, HBIG                           2. If inadequate @,
                            x 1 and vaccine                                    initiate revaccination
                            booster
-----------------------------------------------------------------------------------------------------
 * Hepatitis B surface antigen.
 + Hepatitis B immune globulin; dose 0.06 mL/kg intramuscularly.
 & Hepatitis B vaccine.
 @ Responder is defined as a person with adequate levels of serum antibody to hepatitis B
   surface antigen (i.e., anti-HBs >=  10 mIU/mL); inadequate response to vaccination defined as
   serum anti-HBs < 10 mIU/mL.
** Antibody to hepatitis B surface antigen.
=======================================================================================================

TABLE 4. Summary of ACIP recommendations concerning immunization of health-care workers with special conditions
========================================================================================================================================
                                                                 Severe                                                Alcoholism
                                                                 Immuno-                                              and Alcoholic
Vaccine                          Pregnancy    HIV Infection   suppression*    Asplenia   Renal Failure    Diabetes      Cirrhosis
-----------------------------------------------------------------------------------------------------------------------------------
BCG                                  C              C              C             UI            UI            UI            UI
Hepatitis A                          UI             UI             UI            UI            UI            UI             R +
Hepatitis B                          R              R              R             R             R             R              R
Influenza                            R &            R              R             R             R             R              R
Measles, Mumps, Rubella              C              R @            C             R             R             R              R
Meningococcus                        UI             UI             UI            R +           UI            UI            UI
Poliovirus vaccine,                  UI             UI             UI            UI            UI            UI            UI
  inactivated (IPV) **
Poliovirus vaccine, live,            UI             C              C             UI            UI            UI            UI
  oral (OPV) **
Pneumococcus +                       UI             R              R             R             R             R              R
Rabies                               UI             UI             UI            UI            UI            UI            UI
Tetanus/diphtheria +                 R              R              R             R             R             R              R
Typhoid, Inactivated & Vi ++         UI             UI             UI            UI            UI            UI            UI
Typhoid, Ty21a                       UI             C              C             UI            UI            UI            UI
Varicella                            C              C              C             R             R             R              R
Vaccinia                             C              C              C             UI            UI            UI            UI
-----------------------------------------------------------------------------------------------------------------------------------
 * Severe immunosuppression can be caused by congenital immunodeficiency, leukemia, lymphoma, generalized malignancy or therapy
   with alkylating agents, antimetabolites, ionizing radiation, or large amounts of corticosteroids.
 + Recommendation is based on the person”s underlying condition rather than occupation.
 & Women who will be in the second or third trimester of pregnancy during the influenza season.
 @ Contraindicated in HIV- infected persons who have evidence of severe immunosuppression.
** Vaccination is recommended for unvaccinated health-care workers who have close contact with patients who may be excreting wild
   polioviruses. Primary vaccination with IPV is recommended because the risk for vaccine-associated paralysis after administration of
   OPV is higher among adults than among children. Health care workers who have had a primary series of OPV or IPV who are directly
   involved with the provision of care to patients who may be excreting poliovirus may receive another dose of either IPV or OPV. Any
   suspected case of poliomyelitis should be investigated immediately. If evidence suggests transmission of wild poliovirus, control
   measures to contain further transmission should be instituted immediately, including an OPV vaccination campaign.
++ Capsular polysaccharide parenteral vaccine.

Abbreviations: R=Recommended; C=Contraindicated; UI=Use if indicated.
========================================================================================================================================

TABLE 5. Work restrictions * for health-care workers (HCWs) exposed to or infected
with certain vaccine-preventable diseases
===========================================================================================================
Disease/Problem                    Work Restriction                     Duration
---------------------------------------------------------------------------------------------------------
Diphtheria
  Active                           Exclude from duty.                   Until antimicrobial therapy is
                                                                        completed and 2
                                                                        nasopharyngeal cultures
                                                                        obtained >=24 hours apart are
                                                                        negative.

  Postexposure
  (Susceptible HCWs;               Exclude from duty.                   Same as active diphtheria
  previously vaccinated HCWs
  who have not had a Td
  booster dose within the
  previous 5 years)

  Asymptomatic carriers            Exclude from duty.                   Same as active diphtheria.

Hepatitis A                        Restrict from patient contact        7 days after onset of jaundice.
                                   and food handling.
Hepatitis B
  HCWs with acute or chronic
  antigenemia:
  -HCWs who do not perform         Standard precautions should          Universal precautions should
  exposure-prone invasive          always be observed. No               always be observed.
  procedures (21)                  restriction unless
                                   epidemiologically linked to
                                   transmission of infection.

  -HCWs who perform                These HCWs should not                Until HBeAg + is negative.
  exposure-prone invasive          perform exposure-prone
  procedures                       invasive procedures until they
                                   have sought counsel from an
                                   expert review panel which
                                   should review and recommend
                                   the procedures the worker can
                                   perform, taking into account
                                   the specific procedure as well
                                   as the skill and technique of
                                   the worker (30).

Upper respiratory infections
 (Persons at high risk for         During particular seasons (e.g.,     Until acute symptoms resolve.
 complications of influenza as     during winter when influenza
 defined by ACIP {3})              and/or RSV are prevalent),
                                   consider excluding personnel
                                   with acute febrile upper
                                   respiratory infections
                                   (including influenza) from care
                                   of high-risk patients.

Measles
  Active                           Exclude from duty                    7 days after rash appears.

  Postexposure                     Exclude from duty.                   5th day after 1st exposure
   (Susceptible personnel)                                              through 21st day after last
                                                                        exposure and/or 7 days after
                                                                        the rash appears.

Mumps
  Active                           Exclude from duty                    9 days after onset of parotitis.

  Postexposure                     Exclude from duty.                   12th day after 1st exposure
   (Susceptible personnel)                                              through 26th day after last
                                                                        exposure or 9 days after onset
                                                                        of parotitis.
Pertussis
  Active                           Exclude from duty                    Beginning of catarrhal stage
                                                                        through 3rd week after onset
                                                                        of paroxysms or until 5 days
                                                                        after start of effective
                                                                        antimicrobial therapy.
  Postexposure
    Symptomatic personnel          Exclude from duty                    5 days after start of effective
                                                                        antimicrobial therapy.
    Asymptomatic personnel         No restriction, on antimicrobial
                                   prophylactic therapy.

Rubella
  Active                           Exclude from duty                    5 days after the rash appears.

  Postexposure                     Exclude from duty.                   7th day after 1st exposure
   (Susceptible personnel)                                              through 21st day after last
                                                                        exposure and/or 5 days after
                                                                        rash appears.

Varicella
  Active                           Exclude from duty                    Until all lesions dry and crust.

  Postexposure                     Exclude from duty                    10th day after 1st exposure
   (Susceptible personnel)                                              through 21st day (28th day if
                                                                        VZIG administered) after the
                                                                        last exposure; if varicella
                                                                        occurs, until all lesions dry and
                                                                        crust.

Zoster
 (Localized in normal person)      Cover lesions; restrict from         Same as varicella.
                                   care of high-risk patients &.

  Postexposure                     Restrict from patient contact.
   (Susceptible personnel)
---------------------------------------------------------------------------------------------------------
* Adapted from:
  - (173) CDC. Recommendations for preventing transmission of human immunodeficiency virus
    and hepatitis B virus to patients during exposure-prone invasive procedures. MMWR
    1991;40(RR-8):1-8.
  - (95) CDC. Guideline for isolation precautions in hospitals. Recommendations of the Hospital
    Infection Control Practices Advisory Committee (HICPAC) and the National Center for Infectious
    Diseases. Infect Control Hosp Epidemiol 1996;17:53-80.
  - (178) Williams WW: CDC guideline for infection control in hospital personnel. Infect Control
    1983;4(Suppl):326-49.
+ HBeAg = Hepatitis B e antigen.
& Patients who are susceptible to varicella and at increased risk for complications of varicella
  (i.e., neonates and immunocompromised persons of any age.)
===========================================================================================================

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