Immunogenicity of the Brazilian hepatitis B vaccine in adults.

OBJECTIVE To evaluate the immunogenicity and safety of a novel hepatitis B vaccine, after increasing antigen concentration to 25 mug, in comparison to the reference vaccine. METHODS Single-blinded randomized trial comparing VrHB-IB (Instituto Butantan) and the reference vaccine (Engerix B(R), Glaxo Smith Kline). Volunteers aged 31 to 40 years were randomized to either experimental (n=216) or control (n=203) groups, and were given three doses of vaccine. The first dose was administered upon recruitment, and the second and third doses 30 and 180 days later, respectively, between 2004 and 2005. Blood samples were collected for analysis before randomization and after the second and third doses. Active search for adverse effects was perforned in the first five days after vaccination. Differences were evaluated using chi-square and Fisher's exact tests, with a 5% significance level. RESULTS No severe adverse effects were observed. Seroprotection was confirmed in 98.6% (213/216) of volunteers in the experimental group and 95.6% (194/203) of those in the control group. Geometric mean titers were 12,557 and 11,673, respectively. CONCLUSIONS The Brazilian vaccine was considered to be equivalent to the reference vaccine and its use is recommended for adults.