Current Trends Update: Influenza Activity -- United
States
Since January 1, 1985, the number of reporting states with
laboratory isolates of type A(H3N2) influenza virus has increased
rapidly. On January 1, the total was eight states; on January 8,
13
states; and on January 15, 22 states (Figure 3). In addition to
the
previous report of a nursing-home outbreak in New York City (1),
nursing-home outbreaks have now been reported in California and
Pennsylvania. In Pennsylvania, four influenza virus isolates were
recovered from elderly patients in an outbreak that affected about
40
(19%) of 210 nursing-home residents in early January in Crawford
County. In California, 23 (46%) of the 50 residents of a nursing
home
in Santa Clara County had influenza-like illnesses in an outbreak
in
late December and early January.
Reported by B DeArmond, MD, Santa Clara County Health Dept,
California
Dept of Health Svcs; J Schivers, MD, Regional Clinical Laboratories
of
Northwest Pennsylvania, Erie, B Kleger, PhD, Pennsylvania Dept of
Health; State and Territorial Epidemiologists and State Laboratory
Directors; Influenza Br, Div of Viral Diseases, Center for
Infectious
Diseases, CDC.
Editorial Note
Editorial Note: Reports of this year's influenza outbreaks
indicate
that persons of all ages are being infected with type A(H3N2)
strains
(1). The current information is consistent with past observations
that, when outbreaks occur in nursing homes, high attack rates can
occur. Although information about the vaccination status of the
affected nursing-home residents has not been reported, previous
studies, particularly during the A/Bangkok/1/79(H3N2) outbreaks in
1982-1983, showed that use of influenza vaccine greatly reduced the
complications from influenza. Because the present type A(H3N2)
strains now causing outbreaks are similar to the A/Philippines/2/82
component of the current vaccine, it is likely that similar
protection
will be conferred. Persons providing medical care to those at high
risk of acquiring severe influenza should continue to offer
influenza
vaccine to those who have not yet received it. Under circumstances
where influenza A virus is already active within the community,
amantadine hydrochloride is recommended to provide protection for
the
first 2 weeks after vaccine administration, as well as to control
outbreaks when they occur (2). Because renal function often
decreases
with age, a reduced dosage of 100 mg/day is generally advisable for
persons aged 65 years and older to minimize the risk of toxicity
(2,3). Amantadine treatment, begun within the first 1 or 2 days of
illness, may also assist in the recovery process for persons with
influenza A infection.
References
CDC. Update: influenza activity--United States. MMWR
1985;34:6,
11.
ACIP. Prevention and control of influenza. MMWR
1984;33:253-60,
265-6.
Committee on Immunization, Council of Medical Societies,
American
College of Physicians. Guide for adult immunization. 1st ed.
Philadelphia: American College of Physicians, 1985.
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