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

Background: Large-scale outbreaks of enterovirus 71 (EV71) infections have occurred in Asia-Pacific regions. Severe complications include encephalitis and poliomyelitis-like paralysis, cardiopulmonary collapse, and death, necessitating an effective vaccine against EV71. Methods: In this randomized Phase I study, we evaluated the safety and immunogenicity of an inactivated alum-adjuvanted EV71 whole-virus vaccine produced on Vero cell cultures. Sixty healthy volunteers aged 20-60 years received two doses of vaccine, administered 21 days apart. Each dose contained either 5 mu g of EV71 antigen with 150 mu g of adjuvant (Group A05) or 10 mu g of EV71 antigen with 300 mu g of adjuvant (Group B10). Serologic analysis was performed at baseline, day 21, and day 42. Results: There were no serious adverse events. Mild injection site pain and myalgia were the most common adverse events with either vaccine formulation. The immunogenicity data showed that 90% of vaccine recipients have a 4-fold or greater increase in neutralization antibody titers (NT) after the first dose, without a further increase in NT after the second dose. The seroconversion rates on day 21 and day 42 were 86.7% and 93.1% respectively, in Group A05, and 92.9% and 96.3%, respectively, in Group B10. Thus, 5 mu g and 10 mu g of the EV71 vaccine can induce a remarkable immune response in healthy adults after only the first vaccination. Conclusion: The 5 mu g and 10 mu g adjuvanted EV71 vaccines are generally safe and immunogenic in healthy adults. (c) 2013 Elsevier Ltd. All rights reserved.