Trials of intradermal hepatitis B vaccines in Gambian children.

Three trials of intradermal hepatitis B virus (HBV) vaccines were made in Gambian children. In the first trial HBV vaccine (1 microgram) was given to neonates in the same syringe with BCG followed by two further does of 1.0 microgram of intradermal HBV vaccine. The trial was a failure, for 19 of 32 subjects had an HBV surface antibody response of less than 10 m.i.u./ml. In the second trial in young children two different regimes were used: two doses of 2 micrograms HBV vaccine were given intradermally after a 20 micrograms intramuscular dose or three doses of 2 micrograms were given intradermally. In both cases geometric mean antibody responses were significantly lower than in the control group who were given 20 micrograms HBV intramuscularly followed by two 10 micrograms doses intramuscularly. Vaccine failures, defined as the presence of HBV surface antigen or core antibody or absence of surface antibody, were also significantly higher in the intradermal groups. In the third trial 4 micrograms of vaccine were given intradermally to 20 young children with a multiple orifice head fired by a jet gun: all had a good HBV surface antibody response of greater than 100 m.i.u./ml of serum.