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 kg, in comparison to the reference vaccine. METHODS: Single-blinded randomized trial comparing VrHB-IB (Institute Butantan) and the reference vaccine (Engerix B+, 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.Original Abstract: OBJETIVO: Avaliar a imunogenicidade e seguranca da vacina contra hepatite B, apos o aumento na concentracao do antigeno HBsAg para 25 kg, em comparacao a vacina de referenda. MATODOS: Ensaio com alocacao aleatoria e mascararmento simples, comparando a VrHB-IB (Instituto Butantan) com a vacina de referSncia (Engerix B+, Glaxo Smith Kline). Os voluntarios, entre 31 e 40 anos de idade (n=419), foram alocados aleatoriamente ao grupo experimental (n=216) ou ao grupo controle (n=203), e receberam tres doses de vacina. A primeira dose foi administrada no momento do recrutamento, a segunda e terceira 30 e 180 dias depois respectivamente, entre 2004 e 2005. Amostras de sangue foram colhidas para analise sorologica antes da randomizacao, e apos a segunda e terceira doses. Foi realizada a vigilancia ativa de eventos adversos durante os cinco primeiros dias apos a vacinafao. As diferencas foram avaliadas pelos testes do qui-quadrado e exato de Fisher, com nivel de significancia de 5%. RESULTADOS: Nao se observaram eventos adversos graves. A soroportecao foi confirmada em 98,6% (213/216) dos voluntarios do grupo experimental, em comparacao a 95,6% (194/203) do grupo controle Os titulos geometricos medios fo