Hepatitis B vaccine: efficacy in high-risk settings, a two-year study.

A formalin-treated hepatitis B vaccine in the form of purified hepatitis B surface antigen (HBsAg) was prepared from asymptomatic human HBsAg carriers. Its safety and potency were tested in 5 chimpanzees. The vaccine was administered to 264-individuals. The results of the first 173 immunizations--46 hemodialysis patients and 127 staff members--are presented. Potency was ascertained and efficacy assessed by the development of humoral immune responses to HBsAg (anti-HBs antibody) and seroepidemiologic studies of vaccinated and nonvaccinated subjects. The results, 2 years after immunization, suggest that the vaccine was protective against hepatitis B infection in high-risk hemodialysis settings. Preliminary studies with an inactivated hepatitis B vaccine similarly prepared, but with aluminum hydroxide as adjuvant, indicate that a such a preparation induces a more rapid and stronger anti-HBs response.