EFFICACY OF HEPATITIS-B VACCINE IN THE GAMBIAN EXPANDED PROGRAM ON IMMUNIZATION

Because of the high prevalence of hepatitis B virus (HBV) infection in The Gambia, HBV vaccination has been incorporated into the national e xpanded programme on immunisation. We have assessed the efficacy of th e vaccine against HBV infection and chronic carriage by examining 720 3-4-year-old children who had received the vaccine in infancy and 816 who had not received it. The vaccine was 84% (95% CI 78-89%) effective against infection and 94% (84-98%) effective against chronic carriage . Vaccinated infants of mothers positive for hepatitis B surface and e antigens were at greater risk of breakthrough infection and chronic c arriage than infants of uninfected mothers. The high vaccine efficacy against the HBV carrier state, the main risk factor for the developmen t of chronic liver disease and liver cancer, offers hope that the prev alence of these diseases may be reduced in the future.