Efficacy of low dose intradermal hepatitis B vaccine: results of a randomized trial among health care workers.

ABSTRACT

BACKGROUND: Hepatitis B virus (HBV) infection is an occupational health hazard among the healthcare workers. Vaccination against HBV has been established to be the most effective preventive strategy. The present study was designed to assess the efficacy of low dose intradermal HBV vaccine among the nursing staff in a tertiary care hospital setting. PATIENTS AND METHODS: Staff nurses working in our hospital were included in the study as vaccine recipients. Each staff nurse was tested for HBsAg and anti-HBs (commercial ELISA). Those who tested negative for both the above markers were randomized to receive either three doses of intramuscular (i.m.) HBV vaccine (20 micrograms m each dose) at 0, 1 and 6 month interval or three doses of intradermal HBV vaccine (2 micrograms m each dose) at similar intervals. Each vaccine recipient was tested for the presence of anti HBs (commercial ELISA) at the end of 1 month and 1 year after the last dose of the vaccine. The anti-HBs titres were also estimated simultaneously in them. RESULTS: Out of 153 staff nurses screened, 19 were either positive for HBsAg (n = 1) or anti HBs (n = 18). 96(72%) of the remaining 134 nurses agreed to receive HBV vaccine (i.m.--48, intradermal--48). At the end of 1 month after last dose of the vaccine, all vaccinees in both the group tested positive for anti-HBs. However the anti-HBs titres at 1 month were significantly higher among intramuscular vaccinees than the nurses receiving the vaccine through intra-dermal route (253 +/- 127.7 mIU/ml vs 151.3 +/- 92.8 mIU/ml, P < 0.001). Eighty four (85.5%) of these 96 vaccine recipient were available for evaluation of anti-HBs titre at the end of 1 year after the last dose of vaccine (1M group = 40, Intradermal group = 44). All the nurses continued to be positive for anti-HBs at the end of 1 year but the anti HBs-titre among i.m. vaccine recipient continued to remain at a significantly higher level than the similar titre among the intradermal vaccine recipients (256.4 +/- 124.7 mIU/ml vs 121.6 +/- 122.4 mIU/ml p < 0.001). CONCLUSION: Intradermal route for HBV vaccine had similar immunogenic efficacy as the conventional intramuscular route, but the dose required in the former route is one tenth of the intramuscular route. Therefore intradermal route may reduce the cost of HBV vaccine markedly.