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

Abstract

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<0.0001). The reduction of incidence in the vaccinees was as high as 92.3 per cent; none of the vaccinees with a detectable immune response to the vaccine had clinical hepatitis B or asymptomatic antigenemia. A significant reduction of incidence was already seen within 75 days after randomization; this observation suggests that the vaccine may be efficacious even when given after exposure. (N Engl J Med. 1980; 303:833–41.)