In 1985, a hepatitis B (HB) vaccination strategy against vertical HB virus transmission was introduced in Japan that recommended vaccination of infants at two, three, and five months of age (delayed strategy). This schedule was revised in 2013, recommending to vaccinate at birth and at 1 and 6 months of age (non-delayed strategy). We aimed to compare the vertical HB virus transmission rates and immunogenic responses between these two vaccination strategies. This Japanese multicenter prospective cohort study included 222 infants born between 2008 and 2017 to serum hepatitis B surface (HBs) antigen (HBsAg)-positive mothers. During the study period, 136 and 86 infants received delayed and non-delayed strategies, respectively. A positive vertical HB virus transmission was defined as a positive serum HBsAg status. Seropositive immunogenic response was defined as a serum anti-HBs titer of ≥10 mIU/mL. Post-vaccination serum HBsAg positivity rates did not differ significantly between the delayed (0/136 [0.0%, 95% confidence interval, 0.0-2.7%]) and non-delayed (2/86 [2.3%, 95% confidence interval, 0.3-8.1%]) strategy groups. Seropositive immunogenic response rates were 100.0% (136/136) and 97.7% (84/86), respectively. Although this study was under-powered to detect a statistically significant result, no vertical HB virus transmission was observed in the delayed strategy.
Keywords: hepatitis B surface antigen; hepatitis B virus; immunogenic response; mother-to-child infection; prevention.