Anti-HBs levels among children and adolescents with complete immunization schedule against hepatitis B virus. A cross-sectional study in Blumenau, State of Santa Catarina, Brazil, 2007-2008

introduction: vaccination is the main tool for preventing hepatitis b virus (hbv) infection; however, following the completion of the vaccination series, the concentrations of anti-hbs can decline over the years and reach levels less than 10miu/ml. the persistence of protection in these individuals is still unknown. the present study aimed to determine the anti-hbs antibody levels among children and adolescents who had received a complete vaccination course for hepatitis b. methods: antibodies against hbv surface antigen (anti-hbs) were tested in 371 individuals aged 10 to 15 years-old. results: volunteers who showed undetectable quantities of anti-hbs accounted for 10.2% of the population studied and 39.9% presented antibody titers of less than 10miu/ml. anti-hbs > 10miu/ml were verified in 49.9%. conclusions: these results corroborate other studies indicating levels of anti-hbs below 10miu/ml in vaccinated individuals. additional studies are required to assess whether this indicates susceptibility to hbv infection and the need and age for booster doses.