High risk of mumps infection in children who received one dose of mumps-containing vaccine: waning immunity to mumps in children aged 2-5 years from kindergartens in Jiangsu Province, China

Abstract

ABSTRACT Background During the period of immunization with a single-dose measles-mumps-rubella (MMR) vaccine, which has been available since 2008in China, the incidence of mumps in children aged 2–5 years has been high. The aim of this study was to determine the immunity profile of mumps in children aged 2–5 years as part of the assessment of the MMR vaccination strategy. Methods A cross-sectional survey of IgG antibodies against mumps virus in children aged 2–5 years was performed. Analysis by enzyme-linked immune sorbent assay(ELISA)was performed to measure IgG antibodies against mumps virus in the sera of 2-to5-year-old children who had been vaccinated with at least one dose of MMR vaccine. Results Mumps outbreaks mainly occurred in kindergarten and primary schools and primarily involved children in kindergarten from 2015-2016 in Jiangsu Province. In total, 4,033 children were surveyed. The overall seroprevalence of mumps antibodies was 79.0% (95% CI:78.4–79.6), and the geometric mean concentration (GMC) was 323.6 mIU/ml (309.0–338.8). Both univariate and multivariate survival analysis of seroprevalence showed that several factors contributed to having significant seroprevalence among the 2-to-5-year-old group (P < .05). The seroprevalence of children with a single-dose MMR vaccine regimen (78.4%, 95% CI: 77.8–80.4) was significantly lower than that of children with a two-dose MMR vaccine regimen (96.5%, 95% CI: 88.6%-96.1%). The seroprevalence rate was negatively correlated with time since inoculation (P < .01). Conclusion Children who received a single dose of MMR vaccine in kindergarten, particularly the 2-year-old group in the northern region of Jiangsu Province, China, are at high risk of mumps infection. Our study demonstrates thata single-dose MMR vaccine regimen has a limited effect on controlling mumps, which highlights the benefit of introducing a two-dose MMR vaccine schedule.