Efficacy of a Hepatitis E Vaccine

Larry M. Baddour, MD reviewing Zhang J et al. N Engl J Med 2015 Mar 5.

A recombinant vaccine was immunogenic and protective for up to 4.5 years.

Although hepatitis E virus (HEV) generally does not cause chronic infection except in immunocompromised individuals, it is a major cause of acute hepatitis globally, with high case fatality rates in pregnant women. In a previous randomized, placebo-controlled, double-blind, phase III trial, researchers in China evaluated the efficacy of a candidate vaccine in healthy adults (NEJM JW Infect Dis Oct 2010 and Lancet 2010; 376:895). Promising results at 19-month follow-up led to licensure of the vaccine in China.

Now, researchers (some of them employees of the vaccine maker) have followed the trial participants for 54 months to determine the vaccine's long-term efficacy, immunogenicity, and safety. During the extended follow-up period, double-blinding was continued with respect to treatment assignment. A hepatitis surveillance system was used to identify suspected cases of hepatitis.

Overall, 112,604 participants were randomized to receive three doses (0, 1, and 6 months) of either hepatitis E vaccine or hepatitis B vaccine (placebo). Seven cases of HEV infection occurred in the hepatitis E vaccine group versus 53 in the control group, for an efficacy rate of 87% (95% confidence interval, 71%–84%).

Based on geometric mean concentrations of IgG antibodies, 87% of hepatitis E vaccine recipients who had been seronegative prior to immunization and had received all three doses remained seropositive at 54-month follow-up. Rates of serious adverse events were similar between groups; none of the serious events were deemed vaccine-related.

Citation(s):

Zhang J et al. Long-term efficacy of a hepatitis E vaccine. N Engl J Med 2015 Mar 5; 372:914.