Study on factors associated with seroprotection after measles vaccination in children of 6-14 years in Eastern China

Abstract

Measles cases have occurred in individuals with histories of vaccination against the disease in Zhejiang Province, China. The purposes of this study were to determine the seroprevalence of immunoglobulin G (IgG) measles antibodies in vaccinated individuals, to explore the waning kinetics of measles antibody among children after receipt of a measles-containing vaccine, and to define high-risk groups in the population. A seroprevalence survey of measles antibody was conducted with 1900 randomly selected and age-stratified participants aged 6-14 years in Zhejiang province. In our study, seronegative persons accounted for 7.17% of study participants. A case-control study of participants who had received at least one dose of measles-containing vaccine was conducted, with 123 cases of immune failure and 1593 controls with immune success. Multivariate logistic regression analysis showed that age, and number of doses were the influencing factors for measles immunization failure. The older a participant (odds ratio [OR] = 1.164), the more likely that measles vaccine immunity failed. In addition, immune failure was more likely to occur after one dose of MCV than two doses (OR = 0.008) or three doses and more (OR = 0.047). In a univariate logistic regression analysis, we found that immune failure was more likely to occur with MCV vaccination beginning at 8 months than at 9-11 months (OR = 0.562) and the subjects whose registration residence was in other cities in Zhejiang province (OR = 3.527). However, these differences in seropositivity were not significant in the multivariate logistic regression analysis. The exponential regression equation of the attenuation model after measles immunization was y = 884.64e^-0.057x (R² = 0.0521, p < 0.001), and results showed that the measles geometric mean concentration of IgG antibodies was approximately 884.64 mIU/ml after the last MCV vaccination and decreased with time since last vaccination.

Keywords: Immunity; Measles; Measles-containing vaccine (MCV).