Hepatitis B virus vaccine in The Gambia, West Africa: synergy between public health research and practice.

Hepatitis B virus infection is endemic in West Africa, and as a result, this region has a high rate of hepatoma. The recent development of an effective, safe vaccine against hepatitis B virus that provides durable immunity may now make feasible the prevention of persistent hepatitis B virus infection and thus the prevention of hepatoma. A comprehensive primary health care program in which over 70% of children in The Gambia, West Africa, receive all their childhood immunizations afforded a unique opportunity to carry out a large public health research program to prevent hepatoma and at the same time strengthen the country's primary health care program. In 1986, phased introduction of hepatitis B virus vaccine was initiated in The Gambia's Expanded Programme on Immunization. By 1990, 124,577 children had been carefully identified and recruited into the 35-year longitudinal cohort study; 59,803 of these children received hepatitis B virus vaccine. The other 62,774 unvaccinated children will serve as controls. Preliminary studies have demonstrated that the rate of hepatitis B virus infection has fallen to less than 5% in children who received all four doses of hepatitis B virus vaccine. This study should provide the data from which the protective efficacy of hepatitis B virus vaccine against hepatoma can be accurately determined. In addition, it has energized The Gambia's Expanded Programme on Immunization so that at present more than 90% of all children are receiving all their childhood immunizations. This model cancer prevention program demonstrates the potential synergy between public health research and practice.