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Recombinant Hepatitis E Vaccine Is Effective in Preventing Infection

This vaccine could have a substantial effect on HEV-associated morbidity and mortality worldwide.

Although hepatitis E virus (HEV) infection is uncommon in the U.S., it is a major cause of acute hepatitis in developing countries. As much as one third of the entire world population probably has been infected with HEV. The overall case fatality rate for acute disease is 1% to 3%, but, in pregnant women, acute severe hepatitis is common, and the case fatality rate is 5% to 25%. The aim of this partially industry-sponsored, randomized, double-blind, phase II trial was to determine the efficacy of a recombinant-protein HEV (rHEV) vaccine.

A total of 5323 healthy adult men and nonpregnant women were recruited from 61 Nepalese Army units; however, only 2000 patients with absent or low anti-rHEV immunoglobulin levels (<20 Walter Reed antibody units/mL) were enrolled. Subjects were given doses of vaccine or placebo intramuscularly at 0, 1, and 6 months; 84% of subjects received all three doses. The primary study endpoint was prevention of definite HEV infection occurring at least 14 days after the third dose of vaccine. Acute HEV infection (signs, symptoms, and laboratory testing consistent with acute hepatitis) was identified by active surveillance. The presence of PCR-identified HEV RNA and appropriate titers of anti-rHEV immunoglobulins were required to diagnose hepatitis.

Acute HEV infection developed in 69 participants: 3 in the vaccine group (0.3%) and 66 in the placebo group (7.4%). The efficacy of a three-dose vaccine course was 95.5% (95% CI, 85.6%–98.6%). The efficacy of a two-dose vaccine course was 85.7%. Injection-site pain was more common in the vaccine group (P=0.03); other adverse events occurred at similar rates in the groups.

Comment: This very effective recombinant HEV vaccine could have a major effect on morbidity and mortality associated with HEV infection worldwide, and it could be very beneficial for travelers to HEV-endemic areas. However, further studies are required to evaluate its durability, its efficacy in pregnant women, and its potential role in preventing subclinical infections (which might contribute a large infectious reservoir).

— Atif Zaman, MD, MPH

Published in Journal Watch Gastroenterology February 28, 2007

Citation(s):

Shrestha MP et al. Safety and efficacy of a recombinant hepatitis E vaccine. N Engl J Med 2007 Mar 1; 356:895-903.

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