An effective intradermal hepatitis B vaccination.

Small dose intradermal (i.d.) inoculation methods of hepatitis B vaccine have been reported to be effective and economical. We determined the best method to obtain high antibody levels within a short period of time and for the long-term maintenance of these levels. A total of 173 female students were randomly allocated to seven groups: six i.d. inoculation groups, to which 6-12 micrograms was administered in three or four divided doses (Groups A-F), and a control group (Group G) which received three 10 micrograms intramuscular (i.m.) inoculations. Serum hepatitis B antibody levels were quantified in weeks 4 and 8, and months 4, 7, and 12. Positivities in all groups were not significantly different at each measurement time. In month 4, geometric mean antibody levels in the three i.d. groups (10-12 micrograms in three divided doses; 79.1-107.0 IU l-1) were significantly higher than in Group G, which had received two of three i.m. injections (17.6 IU l-1; P < 0.01, P < 0.05). In the group which received four 2 micrograms i.d. inoculations, the level was higher than in Group G in month 7, but lower in month 12. It was concluded that three i.d. inoculations, each of 4 micrograms, may be used to obtain high antibody levels within a short period of time. However, it is recommended that a 10 micrograms i.m. injection in month 6 is applied as a booster. Consequently, we could not present an economic and effective low-dose intradermal inoculation method.