The second injection of hepatitis B after full term should not be postponed for one month at the latest. If there is no special reason, it is best to strictly follow the process of hepatitis B vaccination to implement. Hepatitis B is a common infectious disease and the hepatitis B vaccine can effectively prevent hepatitis B virus infection. Newborns receive their first dose of hepatitis B vaccine on the first day of life, a second dose at one month, and a third dose at six months. If at one month, the child develops symptoms such as fever, jaundice, runny nose, cough, diarrhea, etc., he or she cannot be vaccinated, but the second dose should not be postponed for more than one month at the latest, because the interval is too long, which is not conducive to the formation of antibodies and the maintenance of antibody levels, and should be replenished as early as possible. Babies need to be vaccinated with various vaccines after birth and must be vaccinated on time. After vaccination, babies should be observed for any adverse reactions, and those who are serious need to seek medical attention.