RESUMO
INTRODUCTION: There are controversies over the long-term persistence of post vaccination immunity to hepatitis B and the need for booster doses of the vaccine. The aim of this study was to verify antibody levels of antibody against hepatitis B virus surface antigen (anti-HBs) in children aged 1 to 15 years who received vaccination against hepatitis B in the central province of Iran, Semnan. MATERIALS AND METHODS: We performed a seroepidemiological survey (n = 210) of anti-HBs in 2011 in the central province of Iran, Semnan using enzyme-linked immunosorbent assay (ELISA). The levels of anti-HBs < 10 mIU/mL were considered to be negative and samples showing an anti-HBs titer ≥ 10 mIU/mL was considered protective. RESULTS: Protective antibody levels were detected in 88% of the children less than 5 year after vaccination, decreased to 78% between 5 to 10 years after vaccination, and further declined to 74% in 10 years after vaccination, respectively. CONCLUSION: The vaccination program has been proven effective in Semnan and immunological protection against hepatitis B infection was found in the majority of children even more than 10 years after being vaccinated.