of High Coverage with Two Doses of Measles Vaccine

Background: Changes in the epidemiological characteristics of measles since 2007 appeared in the Jiangsu province. Although the reported coverage with two doses of measles vaccine was greater than 95 % in most regions of the province, measles incidence remained high across the whole province. Cross-sectional serological surveys of measles antibodies in the Jiangsu province of China were conducted from 2008 to 2010 to assess and track population immunity. Methods: Measles-specific IgG levels were measured in serum samples using ELISA. GMTs and seroprevalence with 95 % CIs were calculated by region, gender, and age. ANOVA and x2 tests were used to test for statistically significant differences between groups for GMT levels and seroprevalence, respectively. Results: Seroprevalence showed a significantly increasing trend annually (CMH x2 = 40.32, p,0.0001). Although the seroprevalence among children aged 2–15 years was consistently over 95%, vaccine-induced measles antibodies may wane over time. Measles seropositivity in the Jiangsu province was 91.7 % (95 % CI: 90.1–93.2%) in 2010. Among adults aged 15 to 29-year-olds, the seropositivity rate was 88.4 % (95 % CI: 82.7–92.8%). Conclusions: Vaccination strategies may need to be adjusted depending on the individual age and regions, particularly individuals between the ages of 8 months-14 years old and 20–29 years old. Additional SIAs are likely required to eliminat