EPIDEMIC OF MEASLES FOLLOWING THE NATIONWIDE MASS IMMUNIZATION CAMPAIGN

Monday, 31st of March 2014

[source]BMC Infectious Diseases[|source]

In 2005, the Ministry of Health of China pledged to join the global effort to eliminate measles by 2012 (i.e., to reduce measles incidence to below 1/1,000,000, excluding imported cases). An important strategy recommended by the World Health Organization for achieving this goal is the measles mass immunization campaign (MMIC). During fall 2010, China implemented a nationwide MMIC designed to administer one dose of catch-up measles vaccine to all age-eligible children free of charge, regardless of their vaccination or disease history.  Soon after the MMIC, surveillance data detected a measles epidemic in the city. The number of reported measles cases during October to December, 2010 was 10 times as high as that during the same period in 2009.

In this report, the authors investigated this post-MMIC measles epidemic in Wenzhou City to identify factors contributing to this epidemic and risk factors for measles transmission, and to provide evidence-based recommendations for measles elimination strategies in China. Full text findings, discussions and recommendations are accessible at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3606834/

 

ABSTRACT

BACKGROUND: A prolonged measles epidemic occurred in Wenzhou City, China after a nationwide measles mass immunization campaign (MMIC) in 2010. We conducted an investigation to identify factors contributing to this epidemic and to provide evidence-based recommendations for measles elimination strategies in China.

 METHODS: Measles was diagnosed using the national standard case-definitions. We estimated the population vaccination coverage based on the proportion of measles patients that had been vaccinated. In a case–control investigation, all measles patients who received treatment in The Second Affiliated Hospital of Wenzhou Medical College (Hospital S) during November 1 to December 31, 2010 served as cases; controls were randomly selected among all other patients who received treatment in Hospital S during the same time period, frequency matched by month of hospital visit. We reviewed medical records of case- and control-patients to compare their exposure history at Hospital S and to its intravenous rehydration room (IV room) during the incubation period (7–21 days before their illness onset).

RESULTS: The attack rate of measles in Wenzhou City was 3.3/100,000 during September 1, 2010 to January 11, 2011. Children aged 8-11 m had the highest attack rate (171/100,000) of all age groups. In children not age-eligible for the MMIC but should have been routinely vaccinated after the MMIC, the vaccination rate was only 52%. In the case–control investigation, 60% (25/42) of case-patients compared with 21%. (35/168) of control-patients had visited Hospital S (adjusted ORM-H = 5.5, 95% CI = 2.7–11). Among unvaccinated children who had received treatment in Hospital S, 84% (21/25) of case-patients compared 38% (11/29) of control-patients had visited the IV room (adjusted ORM-H = 9.2, 95% CI = 1.5–59).

CONCLUSION: Relaxed routine measles vaccination among children after the MMIC was the main factor responsible for this epidemic. Exposure in the IV room at Hospital S facilitated the epidemic. To reach the goal of measles elimination, the Chinese public health authorities should make greater efforts to improve timely routine measles vaccination, and to reduce nosocomial transmission.