Vaccination can effectively prevent the occurrence of many diseases, childhood vaccines, some can be lifelong immunity, some have a time limit, such as mumps, measles, chicken pox, polio vaccine, are lifelong immunity, after a vaccination, do not need to make up the vaccine. However, some vaccines are time-limited, such as the hepatitis B vaccine, which can only immunize for 5-10 years. There are many Hepatitis B carriers in China, so after successful vaccination, check the Hepatitis B surface antibody regularly, if it decreases or disappears, you need to get a booster shot or re-vaccination.