A Phase I, randomized, open-label study to evaluate the safety and immunogenicity of an enterovirus 71 vaccine.

•We evaluated the safety and immunogenicity of an enterovirus (EV) 71 whole-virus vaccine in a randomized Phase I trial.•The vaccine has been carefully selected, manufactured and fully characterized according to USA FDA regulations.•5μg of EV71 antigen can induce a remarkable immune response in healthy adults after only the first vaccination.•No boosted response was observed after the second vaccination perhaps due to recall immunity induced by the first dose.•Despite the higher does of antigen used, no serious adverse events (SAEs) occurred.