ANTI-HBs IN IMMUNIZED CHILDREN WITH CUBAN HEPATITIS B VACCINE AND IMPACT OF BOOSTER DOSE AFTER FIVE YEARS

Objectives: Hepatitis B virus infection and associated diseases are a major public health problem. This study was planned to find out the persistence of antibody against hepatitis B surface antigen in Iranian vaccinated children after five years. Methodology: Anti-HBs titers in a group of healthy good – responder children who were vaccinated with Cuban hepatitis B vaccine in infancy were measured after five years. Children with antibody titers <100mlU/ml were revaccinated and retested after four weeks. Results: Mean anti-HBs titers in 68 children (29 females, 39 males) were 482.1mIU/mL at six months after the third dose of primary vaccination and 153mIU/mL at five years later. Total mean anti-HBs titers in 36 (52.9%) children out of 68 (17 females, 19 males) were 38.3mIU/ml and 4(5.8%) of 68 children (two of each sexes) had no detectable antibody after five years. Total mean anti-HBs titers in these hyporesponder and nonresponder were 774.3mIU/mL and 625.5mIU/mL respectively after booster dose. Conclusion: In a group of children, who were immunized with Cuban hepatitis B vaccine from birth, anti-HBS titers fell at 6.5 years of age and almost half of children became hypo responder or no responder and their anti-HBs titers developed secondary rise after booster vaccination. All children showed immunologic memory to a booster dose.