Hepatitis B vaccination in infancy in The Gambia: protection against carriage at 9 years of age

To estimate the efficacy in The Gambia (West Africa) of infant hepatitis B vaccination against infection and carriage with the virus at the age of 9 y ears. The HBV status of 9-year old children vaccinated in infancy was compa red to that of unvaccinated children of the same age. Eight percent of the vaccinated children had been infected by HBV compared to 50% of the unvacci nated control group; HBV carrier status was 0.6 and 10% respectively, resul ting in a vaccine efficacy of 83% against infection and of 95% against chro nic carriage. The results show that infant vaccination provides a high leve l of protection at the age of nine years against both HBV infection and chr onic carrier status and no booster dose of vaccine is required in the first decade. These findings support the WHO recommendation for the introduction of I-IBV vaccination into the Expanded Programme on Immunization in Africa . (C) 1999 Elsevier Science Ltd. All rights reserved.