Immunogenicity of a five-microgram dose of hepatitis B vaccine.

The immunogenicity of a 5-micrograms dose of vaccine (H-B-Vax, MSD) was evaluated in 50 young adults (17-19 years). Results were compared to our previous studies using similarly prepared vaccines using 20 micrograms and 10 micrograms per dose with the same trial protocol in a comparable population. Seroconversion rates for the 5-micrograms doses of vaccine were 80% after the first dose and 98% after the second dose. The remaining participants did not develop anti-HBs in the course of the trial. These results are not significantly different from those observed in the 10-micrograms and 20-micrograms studies. The increase of anti-HBs titers was slower for the 5-micrograms group. High geometric mean titers were observed after booster vaccination, but lower for the 5 micrograms (3,591 mIU/ml) than for 10 micrograms (9,277 mIU/ml) and 20 micrograms (12,975 mIU/ml) doses. It is concluded that 5-micrograms dose of the vaccine is effectively immunogenic for young adults.