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Open Access Highly Accessed Research article

Epidemic of measles following the nationwide mass immunization campaign

Jie Gao12, Enfu Chen3, Zhigang Wang4, Jichuan Shen2, Hanqing He3, Huilai Ma2*, Guang Zeng2* and Bao-Ping Zhu2

Author Affiliations

1 Jing’an District Center for Disease Control and Prevention, Shanghai City, People’s Republic of China

2 Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing, People’s Republic of China

3 Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou City, Zhejiang Province, People’s Republic of China

4 Wenzhou Municipal Center for Disease Control and Prevention, Wenzhou City, Zhejiang Province, People’s Republic of China

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BMC Infectious Diseases 2013, 13:139  doi:10.1186/1471-2334-13-139

Published: 18 March 2013

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.