Intradermal vaccination against hepatitis B virus infection in an endemic area (Nigeria), two year results.

To determine the efficacy and safety of hepatitis B vaccine (Hevac B) given intradermally, 125 Nigerians (aged 1 year to 45 years), who were negative for hepatitis B virus markers, and randomised into two groups were vaccinated. Group 1 (64 volunteers) was given 3 monthly doses of 2 micrograms vaccine mixed with adjuvant subcutaneously (Institut Pasteur Production-Hevac B) while group 2 (61 volunteers) received 3 doses of 2 micrograms non-adjuvated vaccine intradermally given 1 month apart. A month after the third dose 83 per cent of group 1, 71 per cent of group 2 showed positive response by developing antibody to hepatitis B surface antigen. The levels of antibody were significantly higher in group 1 at each stage of the follow-up period, including a month after a booster vaccination was given. The positive response was maintained in almost all the initial responders for the 24 month duration of the study. No significant side effect was documented in any of the participants. The results suggest that population at risk in developing countries could be protected with small doses of vaccine administered intradermally.