Hepatitis B vaccine in developing countries: problems and prospects

Hepatitis B vaccines are highly immunogenic. To determine the efficacy of low doses and of the intradermal route of vaccination, 197 Nigerian children were given 3 monthly doses of Hevac B. Of these, 96 had 2 micrograms subcutaneously and 101 had 2 micrograms intradermally. One month after completing the schedule, 82.3% and 74.3% of the respective groups had become anti-HBs positive without adverse side-effects. In the second part of the study, 50 chronic HBsAg carriers were vaccinated. Compared to placebo-treated carriers, no effect was demonstrated with regard to HBsAg clearance or anti-HBs production. Immune complexes were not attributable to Hevac B. No untoward effects were noted. Booster vaccination of 50 initial non-responders resulted in the development of significant levels of anti-HBs in 20 (40%) of the recipients. None of the 'non-responders' developed clinical or virological evidence of HBV infection. It is concluded that low-dose vaccination is effective and that the intradermal route may be useful in developing countries.