Hepatitis B vaccination after the birth of a child refers to the hepatitis B vaccination, and its maintenance time after vaccination varies from person to person, and generally the antibody can be maintained in the body for several years or more than ten years. At present, China has already popularized the vaccination of hepatitis B. Usually, babies are vaccinated with the first injection within 24 hours after birth, and then the second and third injections are given in January and June respectively. After a child receives the full hepatitis B vaccination after birth, the protective effect of the vaccine usually lasts for several years or more than ten years, but there may be individual differences. It is recommended to re-check the titer of hepatitis B surface antibody to determine whether the hepatitis B vaccine is still protective or not. If the titer of antibody is low, the child can receive the full hepatitis B vaccine again for better prevention of hepatitis B virus infection.