Abstract: Objective　To investigate the immunological interruption effect on mother-to-child transmission in children with high risk of hepatitis B virus (HBV) infection. Methods　The clinical data of 450 children at high risk of HBV infection from January 1, 2012 to December 30, 2017 were analyzed retrospectively. Results　Four hundred forty five children (238 boys; 212 girls) were followed up until 2.6±1.8 years old. Eight children showed positive hepatitis B surface antigen (HBsAg), indicating chronic HBV infection. Titers of anti-HBs were <10 mIU/mL in 68 cases, 10~100 mIU/mL in 171 cases, and ≥ 100 mIU/mL in 203 cases. A total of 180 children with weak response or no/low response to the first vaccination were given intensive hepatitis B vaccination, and 176 cases (97.78%) had the titer of anti-HBs >100 mIU/mL at reexamination. According to the umbilical cord blood HBV-DNA load (≤1.0×102 IU/mL, 1.0×102-1.0×104 IU/mL, 1.0×104-1.0×106 IU/mL and >1.0×106 IU/mL), all children were divided into 4 groups, and the immune response rates of 4 groups were 99.8%, 60%, 46.7%, and 40%, respectively, and there were statistically differences among the groups (P<0.001). Among the 8 patients who failed to block mother-to-child transmission of HBV, 7 had high HBV DNA load in umbilical cord blood, among whom the HBV DNA load was 1.0×103-1.0×105 IU/mL in 4 patients and >1.0×105 IU/mL in 3 patients. Conclusion　The combination of immunoglobulin and hepatitis B vaccine can effectively interrupt the mother-to-child transmission of HBV. The failure of immune interruption is related to HBV DNA load in umbilical cord blood. Strengthened vaccination of hepatitis B vaccine can significantly increase the titer of anti -HBs.

Key words: hepatitis B virus;　vertical transmission;　immunity;　interruption