Hepatitis B Vaccine: Demonstration of Efficacy in a Controlled Clinical Trial in a High-Risk Population in the United States

We assessed the efficacy of an inactivated hepatitis B vaccine in a placebo-controlled, randomized, double-blind trial in 1083 homosexual men known to be at high risk for hepatitis B virus infection. The vaccine was found to be safe, and the incidence of side effects was low. Within two months, 77 per cent of the vaccinated persons had high levels of antibody against the hepatitis B surface antigen. This rate increased to 96 per cent after the booster dose and remained essentially unchanged for the duration of the trial. For the first 18 months of follow-up, hepatitis B or subclinical infection developed in only 1.4 to 3.4 per cent of the vaccine recipients as compared with 18 to 27 per cent of placebo recipients (P