Seroconversion after hepatitis B vaccination in healthy young adults, and the effect of a booster dose.

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.