Progress Toward Elimination of Rubella and Congenital Rubella Syndrome --- the Americas, 2003--2008

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In 2003, the Pan American Health Organization (PAHO) adopted a resolution calling for rubella and congenital rubella syndrome (CRS) elimination in the Americas by the year 2010 (1). Elimination was defined as the interruption of endemic rubella virus transmission in all countries of North America, Central America, South America, and the Caribbean for more than 12 months and no occurrence of CRS cases attributed to endemic transmission (2). To accomplish this goal, PAHO developed a rubella and CRS elimination strategy (3) to 1) introduce rubella-containing vaccine (RCV) into routine vaccination programs of all countries for children aged 12 months and reach >95% coverage in all municipalities, 2) conduct a one-time mass campaign among adolescents and adults and periodic follow-up campaigns among children aged <5 years (4), and 3) integrate rubella surveillance with measles surveillance and initiate CRS surveillance. During 1998--2006, confirmed rubella cases decreased 98% (from 135,947 to 2,998) in the Americas. However, in 2007, rubella outbreaks with a total of 13,014 cases occurred in three countries (Argentina, Brazil, and Chile), primarily in males not included in previous vaccination campaigns. This report summarizes overall progress toward reaching the 2010 goal of eliminating rubella and CRS. With completion of campaigns in Argentina, Brazil, and Haiti, all countries will have implemented the recommended PAHO strategy by the end of 2008, with the expectation of reaching the 2010 rubella and CRS elimination goal.

Routine Vaccination

All 38 countries and territories in the Americas,* with the exception of Haiti, have introduced measles-mumps-rubella vaccine (MMR) in their routine immunization schedules. Beginning in 2009, Haiti will introduce measles-rubella (MR) vaccine in its routine immunization program, after completion of a one-time MR mass vaccination campaign.

In the Americas, routine MMR vaccination coverage is calculated by countries in one of three ways: based on the number of doses administered (34 countries), nominal registries (Mexico and Uruguay), and coverage surveys (Canada and the United States). Reported regional routine first dose MMR (MMR1) coverage at age 12 months was 93%--94% during 2003--2007 (Figure). In 2007, MMR1 coverage of >95% was reported in 19 (51%) countries, 90%--94% in seven (19%) countries, 80%--89% in seven (19%) countries, and <80% in four (11%) countries. In 2007, of the 20 countries and territories reporting administration of a second routine MMR dose (MMR2), reported coverage was >95% in three (15%) countries, 90%--94% in three (15%) countries, 80%--89% in eight (40%) countries, and <80% in six (30%) countries. In 2009, 10 additional countries^§ will begin monitoring and reporting MMR2 dose coverage.^¶

Supplementary Immunization Activities

As part of the PAHO rubella and CRS elimination strategy, two different types of supplementary immunization activities (SIAs) are recommended: one-time SIAs targeting all adolescents and adults, and periodic follow-up SIAs usually targeting children aged 1--4 years. One-time SIAs targeting all adolescents and adults are intended to quickly interrupt rubella virus transmission and prevent future CRS cases (5). Periodic follow-up campaigns provide a second opportunity to vaccinate children who were never vaccinated or who failed to develop an immune response.

During 1998--2008, approximately 250 million adolescents and adults in 32 countries and territories were vaccinated against rubella in SIAs.** Three countries initially only vaccinated females during SIAs: Chile vaccinated females aged 10--29 years in 1999, Brazil vaccinated females aged 12--39 years during 2001--2002, and Argentina vaccinated females aged 18--39 years in 2006. After those SIAs, transmission and outbreaks of rubella mainly occurred among adolescent and adult males in the three countries. Subsequent SIAs were conducted during 2007 and 2008 in Chile (1.3 million males aged 19--29 years in 2007), Brazil (70 million males and females aged 20--39 years and 12--39 years in five selected states in 2008), and Argentina (6.5 million males aged 16--39 years in 2008). Aruba and Netherlands Antilles, Canada, the French departments (French Guiana, Guadeloupe, and Martinique), Panama, the United States, and Uruguay introduced RCV in the routine childhood schedule >20 years ago, thus protecting large cohorts of the adult population. As a result, these countries decided not to implement adolescent and adult SIAs. All Latin American and Caribbean countries that have introduced RCV since 1995 have implemented at least one follow-up campaign (Table 1).

Surveillance Activities

Case-based measles and rubella surveillance is carried out in all countries of the Americas and reported weekly to the regional level. All public and private health-care providers are required to report suspected measles and rubella cases, however reporting is incomplete, particularly in the private sector. Since 1996, serum specimens from patients with suspected measles testing negative for measles immunoglobulin M (IgM) antibody have been tested for rubella-specific IgM antibody. In 1999, regional rubella surveillance was integrated with existing case-based measles surveillance in the PAHO regional measles and rubella laboratory network of 21 national and 124 subnational laboratories. Within the integrated measles and rubella surveillance system, measles or rubella cases are counted as suspected when a health-care worker suspects that a patient has measles or rubella infection. Rubella cases are counted as confirmed when a patient has laboratory-confirmed rubella (IgM positive) or an infection that meets the clinical case definition and is linked epidemiologically to a laboratory-confirmed case. A suspected CRS case is defined in any infant whose mother had laboratory-confirmed rubella infection during pregnancy or in any infant who has congenital anomalies compatible with CRS. A confirmed CRS case is defined as infection in a child with compatible birth defects and documented laboratory evidence of rubella infection during the first year of life (6).

During 1998--2006, confirmed rubella cases decreased 98%, from 135,947 to 2,998 (Figure). A shift in distribution and increase in cases in 2007 resulted from outbreaks, particularly among males, in Argentina (96 cases), Brazil (8,683 cases),^§§ and Chile (4,235 cases), countries that initially vaccinated only females in rubella SIAs (Table 2). During January 1--September 20, 2008, a total of 2,039 confirmed rubella cases were reported in the PAHO region, of which Argentina, Brazil, and Chile accounted for 98%. In response to these outbreaks, countries intensified surveillance activities and vaccination interventions by conducting SIAs among adolescents and adults. Countries that have completed SIAs for all adolescents and adults have not reported any endemic rubella cases (Table 1).

In 2007, 975 suspected CRS cases were reported in the 34 countries with CRS surveillance; four countries (Brazil, Chile, Colombia, and Peru) accounted for 947 (97%) of these cases. Nineteen cases were confirmed by detection of rubella IgM antibody, 17 from Brazil and two from Peru. During January 1--September 20, 2008, confirmed CRS cases were reported in Argentina (one), Brazil (three), and Chile (two).

During 2003--2007, wild-type rubella viruses of genotypes 1C and 2B were endemic in the Americas. Viruses of genotypes 1E, 1G, 1j, and 2B have been linked to imported cases.

PAHO recommends the use of performance indicators to measure measles and rubella surveillance quality. The current standardized surveillance indicators and targets recommended in countries of the Americas to monitor progress toward rubella elimination include: 1) weekly notification by 80% of reporting units (i.e., health clinics, usually at least one for each municipality), 2) >80% of suspected measles/rubella cases investigated adequately,^¶¶3) two or more suspected cases of measles or rubella*** per 100,000 persons detected and reported (to monitor the sensitivity of the surveillance) and 4) >80% of suspected measles/rubella cases with serologic testing. In 2007, among 34 reporting countries and territories in the region, these respective targets were met by 88%, 72%, 71%, and 85% of countries. Aruba and Netherlands Antilles, Canada, the French departments, and the United States do not report indicator data regularly.

Beginning in 2009, two additional indicators and targets will be monitored by countries and PAHO: 1) >80% of confirmed cases are accompanied by follow-up of contacts for 30 days (to monitor occurrence of secondary cases) and 2) >80% of outbreaks have adequate specimens collected for virus detection and isolation.

Reported by: C Castillo-Solórzano, MD, C Marsigli, MPH, P Bravo Alcántara, MPH, JK Andrus, MD, AMB Filippis, PhD, MC Danovaro-Holliday, MD, C Ruiz Matus, MD, Comprehensive Family Immunization Project, Pan American Health Organization, Washington, DC. Ministries of health or public health authorities in the countries of the Regions of the Americas. S Reef, MD, SL Cochi, MD, Global Immunization Div, National Center for Immunization and Respiratory Diseases, CDC.

Editorial Note:

In response to ongoing rubella circulation and the potential for major epidemics, PAHO developed a comprehensive strategy in 2004 to eliminate rubella and CRS from the Americas by 2010. Countries have demonstrated progress toward the rubella and CRS elimination goal; however, outbreaks have occurred, primarily among males, in countries that only vaccinated females during mass campaigns. By implementing the comprehensive strategy and including males in SIAs, countries are able to limit or prevent future outbreaks. By the end of 2008, all countries and territories of the Americas will have implemented the PAHO-recommended vaccination strategies.

In 2005, the United States was the first country in the Americas to declare it had eliminated endemic rubella virus transmission (7). In accordance with the PAHO biennial work plan, 20 additional countries are expected to begin the process of verifying interruption of rubella virus transmission in 2009. To prepare for verification of elimination of rubella and CRS in the Americas, PAHO is developing a strategic plan to guide countries on how to document elimination. In addition, in 2007, the 27th Pan American Sanitary Conference approved a resolution that defined the final steps for reaching the rubella elimination goal by 2010, including formation of national commissions to compile and analyze data and an international committee to document progress toward interrupting transmission (8).

As the final stage of rubella elimination approaches, several challenges remain, including the continued risk for rubella importations and limited collection of specimens for virus detection and isolation. To confront the challenges, PAHO has been working with countries to 1) maintain high population immunity through high routine vaccination coverage and completion of high-quality SIAs; 2) maintain high-quality integrated measles-rubella surveillance and CRS surveillance, including distributing practical field guides, monitoring confirmed CRS cases for virus excretion with at least two consecutive negative specimens, and improving the participation of clinicians in the private sector in surveillance activities; 3) strengthen the WHO regional measles and rubella laboratory network in the Americas, including emphasis on obtaining specimens for genotyping; and 4) increase training opportunities for health workers and interdisciplinary teams of epidemiologists, virologists, and clinicians.

References

* Total includes 35 PAHO member states and three participating states (France, The Netherlands, and the United Kingdom) with affiliated territories in the Americas. The groups of territories include three French departments (French Guiana, Guadeloupe, and Martinique), the autonomous region of the Kingdom of the Netherlands (Aruba and Netherlands Antilles), and six United Kingdom overseas territories (Anguilla, Bermuda, British Virgin Islands, Cayman Islands, Montserrat, and Turks and Caicos Islands).

Reported coverage of >95%: Antigua and Barbuda, Argentina, Bahamas, Belize, Brazil, Columbia, Cuba, Dominica, Dominican Republic, Ecuador, El Salvador, Grenada, Guyana, Mexico, Nicaragua, Peru, St. Kitts and Nevis, St. Vincent and the Grenadines, and Uruguay; 90%--94%: Canada, Chile, Costa Rica, Guatemala, St. Lucia, Trinidad and Tobago, and the United States; 80%--89%: Bolivia, Honduras, Netherlands Antilles, Panama, Paraguay, Suriname, and United Kingdom overseas territories; <80%: Barbados, Haiti, Jamaica, and Venezuela. The French departments did not report coverage.

^§ Aruba and Netherlands Antilles, Bahamas, Canada, Costa Rica, French departments, St. Kitts and Nevis, St. Lucia, Suriname, United States, and Uruguay.

^¶¶ Includes two criteria: 1) percentage of persons with suspected measles or rubella with home visit within 48 hours following notification and 2) percentage of persons with the following relevant data: date of notification, date of investigation, date of rash onset, date sample taken, type of rash, presence of fever, date of prior vaccination, and pregnancy status.

For municipalities with less than 100,000 persons, at least one suspected case reported.

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