Abstract
Preventing perinatal transmission is important for hepatitis B (HepB) elimination. We conducted a retrospective cohort study to assess the interval between HepB birth-dose (HepB-BD) to second-dose (HepB-SD) vaccination on perinatal transmission. Among 39,313 infants born to HepB s-antigen (HBsAg)-positive mothers from a Korean national database 38,411 (97.7%) had completed timely immunophylaxis with HepB-BD 41,572 (99.8%) with hepatitis B immune globulin, and 1027 (2.6%) were HBsAg-positive at ≥ 9 months. Maternal factors (i.e. HepB e-antigen status, age, or nationality) were associated with an increased risk of infection whereas short gestational length decreased it. The HepB-BD - HepB-SD interval (<8 vs. ≥8 weeks) did not alter the risk.