Background: The reported coverage of the measles-rubella (MR) or measles-mumps-rubella (MMR) vaccine is greater than 99.0% in Zhejiang province. However, the incidence of measles, mumps, and rubella remains high. In this study, we assessed MMR seropositivity and disease distribution by age on the basis of the current vaccination program, wherein the first dose of MR is administered at 8 months and the second dose of MMR is administered at 18-24 months.
Methods: Cross-sectional serological surveys of MMR antibodies were conducted by collecting epidemiological data in Zhejiang province, China in 2011. In total, 1015 participants were randomly selected from two surveillance sites. Serum MMR-specific immunoglobulin G levels were tested by enzyme-linked immunosorbent assay. The geometric mean titers and seroprevalence with 95% confidence intervals (CIs) were calculated by age and gender. Proportions of different dose of vaccine by age by vaccine were also identified. Statistically significant differences between categories were assessed by the Chi-square test.
Results: Over 95% seroprevalence rates of measles were seen in all age groups except <7 months infants. Children aged 5-9 years were shown lower seropositivity rates of mumps while elder adolescences and young adults were presented lower rubella seroprevalence. Especially, rubella seropositivity was significantly lower in female adults than in male. Nine measles cases were unvaccinated or unknown vaccination history. Among them, 66.67% (6/9) patients were aged 20-29 years while 33.33% (3/9) were infants aged 8-12 months. In addition, 57.75% (648/1122) patients with mumps were children aged 5-9 years, and 50.54% (94/186) rubella cases were aged 15-39 years.
Conclusions: A timely two-dose MMR vaccination schedule is recommended, with the first dose at 8 months and the second dose at 18-24 months. An MR vaccination speed-up campaign may be necessary for elder adolescents and young adults, particularly young females.