RESUMEN
OBJECTIVE: Previous studies have shown that 5% to 15% of healthy people do not show a protective antibody response following hepatitis B vaccination. The study was done to determine the protective efficacy of vaccination in healthy young adults 1 to 4 years after the three dose vaccination series and to study the effect of a booster dose on non-responders and hypo-responders. DESIGN: Prospective intervention study. SETTING: From January to June 2000, Faculty of Medicine, University of Colombo. STUDY GROUP: 258 volunteers from five batches of medical students vaccinated with three doses of the recombinant vaccine at 0, 1 and 6 months. RESULTS: 9.5% were non-responders. Duration of vaccination, sex and body mass index were not significantly associated with anti-HBs levels. 28.6% had potential risk factors for acquiring HBV infection. 86.3% of non-responders developed protective anti-HBs titres after a booster dose. The persistent non-responders did not have a chronic illness or past HBV infection. CONCLUSIONS: A substantial number do not seroconvert after hepatitis B vaccination. Testing of blood for anti-HBs one month after vaccination is recommended to recognise non-responders as a booster dose will be beneficial in the majority of them.