The effects of booster vaccination on hepatitis B vaccine in anti-HBs negative infants of HBsAg-positive mothers after primary vaccination

The purpose of this study was to investigate the changes in anti-HBs IgG levels after booster vaccinations in anti-HBs negative infants of HBsAg-positive mothers. After primary vaccination, the immunization effects of different dosages of booster vaccinations of hepatitis B vaccine (CHO) were compared. A group of 472 newborns were vaccinated with three-dose hepatitis B vaccine at birth, 1 mo and 6 mo of age. Blood serum was collected within 6-12 mo after the third dose, and HBsAg, anti-HBs and anti-HBc levels were determined. Of this group, 101 infants who were both anti-HBs and HBsAg negative were revaccinated with 20 mu g hepatitis B vaccine (CHO), and their antibody titers were monitored. Among these 101 infants, the anti-HBs positive rates (defined as anti-HBs >= 100 mIU/ml) differed after the first and the third dose 79% and 90%, respectively (p < 0.05), while differences in the corresponding geometric mean titers (GMTs) were not statistically significant (629 +/- 3 mIU/ml and 572 +/- 3 mIU/ml respectively, p < 0.05). The anti-HBs GMTs after booster vaccination were 10-fold larger than those before booster vaccination. We conclude that a single booster dose is generally adequate for infants of HBsAg-positive mothers, whereas a further booster dose should be given for non-responders.