Reuters Health Information (2007-02-28): Hepatitis E vaccine effective in high-risk population
Hepatitis E vaccine effective in high-risk population
Last Updated: 2007-02-28 17:00:08 -0400 (Reuters Health)
NEW YORK (Reuters Health) - In a study of healthy subjects from the Nepalese army, use of a recombinant hepatitis E virus (HEV) vaccine was 95.5% effective in preventing hepatitis E infection.
HEV infection is a major cause of morbidity in developing countries and carries an overall case fatality ratio of 1 to 3%, according to the report in The New England Journal of Medicine for March 1. In an earlier study, genotype 1 HEV recombinant protein vaccine was shown to be effective in nonhuman primates. This encouraging result prompted the present randomized clinical trial.
Of the 2000 subjects who were recruited for the study, 1794 received all three vaccine doses, including 898 given active vaccine and 896 given placebo. The vaccine doses were administered at baseline and at 1, and 6 months. The main outcome measure was the development of hepatitis E after receiving the full vaccine schedule.
With the exception of increased injection site pain in the active vaccine group, the groups were comparable in terms of adverse events. Sixty-nine subjects developed hepatitis E and all but three were from the placebo group, senior author Dr. Bruce L. Innis, from GlaxoSmithKline in King of Prussia, Pennsylvania, and colleagues note.
When the analysis was expanded to include all 87 subjects who developed hepatitis E after the first vaccine dose, the efficacy dropped from 95.5% to 88.5%.
In a related editorial, Dr. Krzysztof Krawczynski, from the Centers for Disease Control and Prevention in Atlanta, addresses some of the questions that remain to be answered before the recombinant HEV vaccine is "ready for prime time."
The study he says, "shows in a group of almost exclusively male subjects that recombinant HEV vaccine effectively prevents clinical hepatitis E, although the duration of the induced immunity remains unknown as does the efficacy of the vaccine in preventing asymptomatic HEV infection."
"It will be important to define how this vaccine may affect the reservoir and transmission of HEV," Dr. Krawczynski concludes, "thus determining the overall public health benefit."
N Engl J Med 2007;356:895-903,949-951.