Mother-to-child transmission is the main way for infants and children to be infected with hepatitis B. Hepatitis B mothers are always worried about transmitting hepatitis B to their children, so they actively cooperate with their doctor’s antiviral treatment when it is needed, and their babies are born with hepatitis B vaccine and hepatitis B immunoglobulin. However, we are still unsure about how long the hepatitis B vaccine will work after the baby is born. Will the baby’s hepatitis B surface antigen turn positive later? Will the hepatitis B surface antibody not reach the effective level of protection? These are indeed related to the titer level of hepatitis B surface antibody. It is generally believed that the titer of hepatitis B surface antibody is >10Iu/ml in order to play a sufficient protective role, and if such an immunization level can be achieved, the baby will generally not turn positive for hepatitis B surface antigen. But what we all fail to notice is when is the level of hepatitis B surface antibody titers tested reliable? For children, the risk of being infected with hepatitis B is relatively small, except for mother-to-child transmission. If the mother is among those who are positive for hepatitis B surface antigen, she needs to be screened for hepatitis B surface antibody titers 1-2 months after her baby regularly completes the full course of hepatitis B vaccination; too early (<21 days) is prone to vaccine-related hepatitis B surface antigen positivity, and too late may already have declining antibody titers, easily resulting in unnecessary re-vaccination. It is also not advisable to test for hepatitis B before 9 months of age, as hepatitis B immunoglobulin may still be present in the child's body at this time. Babies with titers of hepatitis B surface antibody <10Iu/ml tested during this period need to receive an additional dose of hepatitis B vaccine and be retested 1-2 months later. If the titer of hepatitis B surface antibody is still <10Iu/ml measured, 2 more doses are required, with an interval of at least 8 weeks between the 2 doses. Children who are still <10Iu/ml retested 1-2 months later are considered non-responders and are likely to be infected with hepatitis B and need to be monitored for hepatitis B V. If the mother does not have hepatitis B, the child with normal immune function is considered not to be at high risk for hepatitis B infection and does not need to be routinely tested for hepatitis B V. Unnecessary testing may result in unnecessary replanting. If the father has hepatitis B, everyday contact does not transmit hepatitis B. Sharing a meal, hugging, and kissing cannot transmit hepatitis B, and it will not be passed on to the baby through sperm, so there is no need to worry and no need for routine testing for hepatitis B. Finally, babies with screening hepatitis B surface antibody titers >10Iu/ml do not need additional hepatitis B vaccination and can be screened for hepatitis B surface antigen and hepatitis B surface antibody every 10 years or so.