We did a randomised, double-blind, placebo-controlled, phase 3 trial. Healthy children aged 6-35 months from four centres in China were randomly assigned (1:1) to receive vaccine or alum-adjuvant placebo at day 0 and 28, according to a randomisation list (block size 30) generated by an independent statistician. Investigators and participants and their guardians were masked to the assignment. Primary endpoints were EV71-associated hand, foot, and mouth disease (HFMD) and EV71-associated disease during the surveillance period from day 56 to month 14, analysed in the per-protocol population. This study is registered with , number .
10?245 participants were enrolled and assigned: 5120 to vaccine versus 5125 to placebo. 4907 (with three cases of EV71-associated HFMD and eight cases of EV71-associated disease) versus 4939 (with 30 cases of EV71-associated HFMD and 41 cases of EV71-associated disease) were included in the primary efficacy analysis. Vaccine efficacy was 90¡¤0 % (95 % CI 67¡¤1-96¡¤9) against EV71-associated HFMD (p=0¡¤0001) and 80¡¤4 % (95 % CI 58¡¤2-90¡¤8) against EV71-associated disease (p<0¡¤0001). Serious adverse events were reported by 62 of 5117 (1¡¤2 % ) participants in the vaccine group versus 75 of 5123 (1¡¤5 % ) in the placebo group (p=0¡¤27). Adverse events occurred in 3644 (71¡¤2 % ) versus 3603 (70¡¤3 % ; p=0¡¤33).
EV71 vaccine provides high efficacy, satisfactory safety, and sustained immunogenicity.
China's 12-5 National Major Infectious Disease Program, Beijing Vigoo Biological.