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Paper of the Month May 2013

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

Vaccine. 2013 May 7;31(20):2471-6


Cheng A, Fung CP, Liu CC, Lin YT, Tsai HY, Chang SC, Chou AH, Chang JY, Jiang RH, Hsieh YC, Su IJ, Chong PC, Hsieh SM.


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.


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 5μg of EV71 antigen with 150μg of adjuvant (Group A05) or 10μg of EV71 antigen with 300μg of adjuvant (Group B10). Serologic analysis was performed at baseline, day 21, and day 42.


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, 5μg and 10μg of the EV71 vaccine can induce a remarkable immune response in healthy adults after only the first vaccination.


The 5μg and 10μg adjuvanted EV71 vaccines are generally safe and immunogenic in healthy adults.