Effectiveness of Hepatitis B vaccination in children of chronic hepatitis B mothers

Objective: Although all newborns in Iran have been vaccinated against hepatitis B since March 1993, routine screening of pregnant women has not been conducted in prenatal care programs, yet transmission of hepatitis B via the maternal-fetal route is still a viable likelihood, which must be entertained. Methods: The subjects were divided into 2 groups. The exposed group comprised 97 vaccinated children whose mothers were seropositive for hepatitis B surface antigen (HBsAg) and had not received hepatitis immunoglobulin at birth. The unexposed group consisted of 87 vaccinated children whose mothers were seronegative for hepatitis B surface antigen. We compared these 2 groups to determine the efficacy of vaccine alone in high-risk children. This study was conducted in Tehran, Iran, from June 2002 to December 2002. All children were born after 1993. Results: Chronic infection (HBsAg positivity) was detected in 14.3% of children in the exposed group. There were no instances of chronic infection in the unexposed group (relative risk [RR]=13.48, 95% confidence intervals [CI] 1.8-100.02). Previous infection of hepatitis B (HBcAb positivity) was found in 29 (29.9%) children in the exposed group, but only one (1.2%) in the unexposed group (RR=26.01, 95% CI: 3.61-186.95). Immunity (HBsAb positivity) in the exposed group measured 48 (49.5%) and unexposed group measured 56 (64.4%) (R.R=0.76, 95% CI: 0.59-0.99). Conclusion: Vaccination alone did not induce immunity against hepatitis B in high-risk children; it seems that routine screening of pregnant women is necessary for determining whether neonates need hepatitis B immunoglobulin after birth.