[Analysis on post-marketing effectiveness and immunogenicity of enterovirus-A71 vaccine]

Objective: To analyze the effectiveness and immunogenicity of enterovirus-A71(EV-A71) vaccine in immunization program. Methods: A cohort study was conducted in immunization clinics in Jing'an district in Shanghai from October to December 2017. Children who received EV-A71 vaccine based on a 2-dose schedule (on day 0 and day 30) were enrolled as vaccine group and those who received no EV-A71 vaccine were enrolled as control group. After 1-year follow-up, the effectiveness and neutralizing antibody level and the positive results of antibody immunogenicity in vaccine group were analyzed. Results: A total of 3 018 children aged 8-20 months were enrolled, in whom 1 211 were in vaccine group and 1 807 were in control group. The vaccine effectiveness was 100% against EV-A71-associated hand, foot, and mouth disease (HFMD) indicated by 1 year follow-up (95%CI: -66.99%-100.00%). The geometric mean titer of neutralizing antibody (GMT) was 41.76 (95%CI: 35.60-49.34) at day 60 and 28.44(95%CI: 23.59-34.54) at day 365 in 124 children in vaccine group. Conclusions: In children, EV-A71 vaccine elicited EV-A71-specific immune response. Less EV-A71-associated HFMD cases have been observed, further observation is needed.