This study is an open-labelled, single-centered, stratified-randomized, phase IV clinical trial. The purpose of this study is to evaluate the immunogenicity and safety of EV71 vaccine (developed by Sinovac Biotech Co., Ltd.) in infants aged 6 to 35 months old, by detecting the dynamic changes of neutralizing antibody at different times after vaccination. The enrolled subjects in this study receive two doses of EV71 vaccine with 1-month interval between doses. To evaluate safety of the vaccine, subjects will be observed for 30 days after the injection for the potential adverse events. To evaluate the immunogenicity of the vaccine, venous blood will be collected for the neutralizing antibody detection prior to vaccination, 10/20/30 days after the 1st dose and 30 days after the 2nd dose vaccination. All subjects will receive blood sampling for three times. Subjects will be randomly assigned to receive blood sampling at 10/20/30 days after 1st dose injection, with a ratio of 1: 1: 1.
The purpose of this study is to evaluate the immunogenicity and safety of EV71 vaccine in infants aged 6 to 35 months old, by detecting the dynamic changes of neutralizing antibody at different time after vaccination