PROGRESS TOWARD CONTROL OF RUBELLA AND PREVENTION OF CONGENITAL RUBELLA SYNDROME --- WORLDWIDE, 2009

Monday, 15th of April 2013

[source]Morbidity and Mortality Weekly Report (MMWR)[|source]

Full text presentation of global progress in Rubella control and prevention of Congenital Rubella Sydrome. Annual reported cases of Rubella by region of WHO are presented with a comparative analysis of trends in the period 2000-2009. Details available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5940a4.htm

Editorial Note

The primary purpose of rubella vaccination is to prevent congenital rubella virus infection, including CRS, which affects an estimated 110,000 infants each year in developing countries. Safe and effective RCVs have been available since 1969. However, until the 1990s, developed countries primarily used RCV because the disease burden caused by rubella virus had not been documented sufficiently in the developing world, and because of the additional cost of the rubella vaccine component when combined with MR or MMR vaccine and concern that the risk for CRS might increase if high vaccination coverage could not be achieved and maintained. Low coverage might result in decreased virus circulation, which could increase the average age of rubella infection for females from childhood to the childbearing years.

Rubella and CRS are vastly underreported to WHO through routine disease surveillance systems. Reporting of rubella and CRS cases in a region is dependent on the number of member states with surveillance systems and the quality of those systems. As a country makes progress on rubella control and CRS prevention, the quality of the surveillance improves to monitor the effectiveness of the vaccination program and the number of reported cases might increase even when the actual number of infections decreases. For example, 46,621 infants with CRS are estimated to be born annually in SEAR, based on seroprevalence data and statistical models; yet, during 2000--2009, a mean of only 13 CRS cases (range: 0--61 cases) were reported by one to four member states annually. As rubella control and surveillance continues to improve in SEAR, the number of reported CRS cases might increase. WHO has published guidelines on CRS surveillance that recommend identifying infants born with congenital defects associated with CRS and follow-up of pregnant women who are infected during pregnancy. Documenting the extent of CRS is challenging because of the difficulty of diagnosis and reporting in settings with limited medical resources. Nevertheless, clusters of children born with CRS have been identified after rubella outbreaks, even in resource-poor settings (e.g., Romania). In the majority of member states in all WHO regions, rubella cases are identified through integrated measles-rubella case-based surveillance.

During the past decade, most member states have increased the frequency of laboratory testing of suspected measles and rubella cases. However, because 20%--50% of rubella infections do not include a rash, many rubella cases will not be detected or reported. In all regions, widespread rubella virus circulation has been documented through serosurveys.

In 2009, two thirds of all WHO member states included RCV as part of their national immunization schedule; however, these member states represent <50% of the global birth cohort. As other member states consider RCV introduction, the potential risk needs to be considered that rubella virus transmission dynamics might be altered such that susceptibility might increase among women of childbearing age, resulting in increased risk for CRS. Therefore, for countries introducing RCV, achieving and maintaining high vaccination coverage is essential. In 2009, of the 130 member states that have introduced RCV, 121 member states had sustained MCV1 coverage >80% and median MCV1 coverage was 96%.

Incorporation of RCV into national childhood immunization schedules is both cost-beneficial and cost-effective (8). Studies in Barbados and Guyana estimated a lifetime cost of treating a single CRS case to be approximately $50,000 in Barbados and $64,000 in Guyana (8). In contrast, rubella vaccine is highly affordable; the incremental costs of incorporating rubella vaccine in MR and MMR vaccines using a 10-dose vial are $0.31 and $0.70--$1.37 per dose, respectively. In introducing RCV, MR and MMR vaccines easily replace single-antigen measles vaccines in routine childhood immunization schedules.

In AMR and EUR, the two WHO regions with rubella elimination goals, rubella cases have decreased more than 97% (9). In September 2010, the Pan American Health Organization (PAHO) announced that AMR had achieved the rubella and CRS elimination goals, based on analysis of surveillance data; efforts are under way to document the elimination of rubella and CRS (10). As regions and member states make progress toward achieving rubella and CRS elimination goals, challenges remain, including the risk for disease importation. To achieve and maintain the elimination goals, member states will need to ensure high vaccination coverage and maintain high-quality, integrated measles-rubella and CRS surveillance.

With the substantial morbidity and cost resulting from infants born with CRS and the ease of introduction of RCV into the routine vaccination program, member states and regions that have not introduced RCV are encouraged to assess their burden of CRS and rubella and to determine whether introduction of RCV is appropriate, and if so, to explore financially sustainable options for providing RCV. Twenty-two member states have sustained MCV1 coverage >80%, but have not yet introduced RCV, largely because of a lack of financial resources. Rubella control and prevention of CRS can be accelerated by integrating rubella into the measles case-based surveillance system, establishing CRS surveillance, and using combined MR and MMR vaccines as part of current measles elimination and global mortality reduction activities.