Epidemic of measles following the nationwide mass immunization campaign.

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BMC Infect Dis. 2013 Mar 18;13:139. doi: 10.1186/1471-2334-13-139.

Epidemic of measles following the nationwide mass immunization campaign.

Gao J¹ Chen E Wang Z Shen J He H Ma H Zeng G Zhu BP.

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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 3.3/100000 during September 1 2010 to January 11 2011. Children aged 8-11 m had the highest attack rate (171/100000) 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.