Evaluation on estimation of routine immunization coverage of the first dose of measles containing vaccine in Zhejiang province

Objective To estimate the routine immunization coverage of the first dose of measles containing vaccine (MCV1) in Zhejiang. Methods The reported routine coverage data of MCV were collected from China immunization information system. The immunization history of measles cases were collected from China measles surveillance system and the estimated coverage was calculated based on vaccine efficacy (VE) of MCV. Results The reported coverage rate of MCV1 was ＞99% in Zhejiang province from 2008 to 2010. Based on the proportion of immunized measles cases and VE of MCV, the estimated coverage rate of MCV1 was 76.65% (VE=82.9%) or 90.53% (VE=95%) in children aged 13-83 months. The estimated coverage rate of MCV1 was 85.86% (VE=82.9%) or 95.40% (VE=95%) in local children and 67.54% (VE=82.9%) or 87.68% (VE=95%) in children among floating population. The timely immunization rate of MCV1 (9 months) was 61.16% (VE=82.9%) or 84.34% (VE=95%). Conclusion There is still a large gap between the reported coverage and the estimated coverage of MCV, and the coverage rate and timely coverage rate of MCV1 were still low. It is necessary to use routine immunization surveillance system based on children's immunization record to understand the real coverage rate of MCV in different estimation ways.