After the birth of a child born to a mother with hepatitis B, the infant receives 3 doses of hepatitis B vaccine (0, 1 month, 6 months) in addition to 1-2 doses of hepatitis B immunoglobulin by intramuscular injection in the routine immunization schedule. Infants are usually examined for the effectiveness of mother-to-child interruption of hepatitis B and the results of hepatitis B vaccination at 7 months of age. The vast majority of infants are usually free of the hepatitis B virus after the combined immunization blockade. Hepatitis B surface antibody levels are highest at 7 months of age, and there is a gradual decline in antibody levels thereafter, with positive levels usually being sufficient. The guidelines recommend intervention for infants with hepatitis B surface antibodies below 100 or less. For infants or children with antibody levels of 10-100, there are individual differences between intervention and non-intervention.