RESUMEN
BACKGROUND: Hepatitis B is a dangerous disease with high morbidity and mortality rates all around the world. Vaccination is the most important way to its prevention and control. This cross-sectional study was carried out to study the levels of immunogenicity to hepatitis B vaccine in students. MATERIALS AND METHODS: Six hundred and forty-four students aged 6-18 years including 316 girls and 328 boys were selected from the Chaharmahal Va Bakhtiari province. Selected students had been received three doses of recombinant vaccine (0, 1, and 6 months). Blood samples were taken and the titers of hepatitis B surface antigen were studied. RESULTS: From a total of 644 students, 396 (61.5%) had a titer lesser than 10 mIu/ml and 248 (38.5%) had a titer higher than 10 mIu/ml. Therefore, the level of respond to vaccine with 95% confidence was 38.5% (34.7%-42.4%). Levels of respond to vaccine were related to age, body mass index (BMI), and educational level and were not related to sex and habit of students. CONCLUSION: Reverse significant relation was seen between the respond to vaccine and age and BMI in a way which the titers of antibody were lower in students with higher age and BMI.