Phase 3 EV71 vaccine increased protection in children

The first enterovirus 71 vaccine candidate to reach phase 3 clinical testing is providing young Chinese children with significant protections against disease caused by enterovirus 71, according to recent study results published in The Lancet.

“Infection with [enterovirus 71] is of particular concern because it can cause severe disease and even death in children; the [enterovirus 71] vaccine could help prevent hospital admission and severe cases,” researchers wrote. “However, few patients in our study were admitted to hospital or had severe disease, therefore the estimates of efficacy against [enterovirus 71] in such patients had wide 95% CIs.”

The randomized, double blind, placebo-controlled phase 3 trial included 10,245 healthy children aged 6 to 35 months. Participants were randomly assigned to receive placebo (n=5,125) or the enterovirus 71 (EV71) vaccine (n=5,120).

Researchers found that the vaccine gave 90% (95% CI, 67.1-96.9) protection against clinical EV71-associated hand, foot, and mouth disease and 80.4% (95% CI, 58.2-90.8) against EV71-associated disease, including neurological complications, for at least 12 months.

They also found that serious adverse events were only reported by 1.2% of participants in the vaccine group compared with 1.5% of participants in the placebo group.

“In the 1-year surveillance period, only a small proportion of cases of [hand, foot and mouth disease] were confirmed as associated with EV71, indicating that EV71 might not be the dominant pathogen in this [hand, foot, and mouth disease] season,” researchers wrote. “Despite its high efficacy for preventing EV71-associated [hand, foot, and mouth disease], the EV71 vaccine might have little part in reducing the overall incidence of [hand, foot, and mouth disease], even by universal mass immunization of children.”

In an editorial accompanying the study, Nigel W. Crawford, BMBS, MPH, and Steve M. Graham, of the University of Melbourne and Murdoch Children’s Research Institute in Australia, said because morbidity and mortality from EV71 is low, the effect of the vaccine will be to reduce hospital admissions.

“The next step is to assess the appropriateness of including an EV71 vaccine in China’s national immunization program, including a cost-effectiveness analysis,” they wrote. “The large disease burden, combined with high vaccine efficacy and local production capacity, will help in formulating this decision.”

Disclosure: The study was supported by China’s 12-5 National Major Infectious Disease Program, Beijing Vigoo Biological. See the study for a full list of disclosures.