RESUMO
BACKGROUND: Combined immunization with hepatitis B immunoglobulin (HBIG) plus hepatitis B vaccine (HB vaccine) can effectively prevent perinatal transmission of hepatitis B virus (HBV). With the universal administration of HB vaccine, anti-HBs conferred by HB vaccine can be found increasingly in pregnant women, and maternal anti-HBs can be passed through the placenta. This study was designed to evaluate the effect of hepatitis B immunization on preventing mother-to-infant transmission of HBV and on the immune response of infants towards HB vaccine. METHOD: From 2008 to 2013, a prospective study was conducted in 15 centers in China. HBsAg-positive pregnant women and their infants aged 8-12 months who completed immunoprophylaxis were enrolled in the study and tested for HBV markers (HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc). Antepartum administration of HBIG to HBsAg-positive women was based on individual preference. HBsAg-negative pregnant women and their infants of 7-24 months old who received HB vaccines series were enrolled and tests of their HBV markers were performed. RESULTS: 1202 HBsAg-positive mothers and their infants aged 8-12 months were studied and 40 infants were found to be HBsAg positive with the immunoprophylaxis failure rate of 3.3%. Infants with immunoprophylaxis failure were all born to HBeAg-positive mothers of HBV-DNA ≥6 log10copies/ml. Among infants of HBeAg-positive mothers, immunoprophylaxis failure rate in vaccine plus HBIG group, 7.9% (29/367), was significantly lower than the vaccine-only group, 16.9% (11/65), p=0.021; there was no significant difference in the immunoprophylaxis failure rate whether or not antepartum HBIG was given to the pregnant woman, 10.3% (10/97) vs 9.0% (30/335), p=0.685. Anti-HBs positive rate was 56.3% (3883/6899) among HBsAg-negative pregnant women and anti-HBs positive rate was 94.2% in cord blood of anti-HBs-positive mothers. After completing the HB vaccine series, anti-HBs positive rate among infants with maternal anti-HBs titers of <10 IU/L, 10-500 IU/L and ≥500 IU/L was 90.3% (168/186), 90.5% (219/242) and 80.2% (89/111) respectively, p=0.011. Median titers of anti-HBs (IU/L) among infants in the three groups was 344.2, 231.9 and 161.1 respectively, p=0.020. CONCLUSIONS: HBIG plus HB vaccine can effectively prevent mother-to-infant transmission of HBV, but no HBV breakthrough infection was observed in infants born to HBeAg-negative mothers who received HB vaccine with or without HBIG after birth. Antepartum injection of HBIG has no effect on preventing HBV mother-to-infant transmission. High maternal titer of anti-HBs can transplacentally impair immune response of infants towards HB vaccine.