A candidate bacterially expressed recombinant hepatitis E virus (HEV) vaccine, HEV 239 vaccine, had been shown promising efficacy in rhesus monkeys.Phase Ⅱ clinical trial found that this vaccine is safe and immunogenic and suggests that vaccination could prevent ongoing HEV infection.A randomized controlled phase Ⅲ clinical trial is being conducted in a rural country of a county located in Jiangsu province, China.Pre-trial serological study involved 1270 health people in this area had shown that the prevalence of antibody against HEV is 46.7%.Follow-up of these individual revealed a spontaneous HEV seroconversion rate of 8.3% per year.