People who are currently negative or weakly positive for Hepatitis B surface antibodies are still at risk of infection, while those who are currently positive or strongly positive for Hepatitis B surface antibodies are usually not infected. Hepatitis B vaccination as a child usually leads to the production of hepatitis B antibodies by the body’s immune system, but it cannot be ruled out that a very small number of vaccinated people who received the hepatitis B vaccine as a child were not successfully immunized. If you were vaccinated as a child and are sure that the immunization is successful, the antibodies against hepatitis B produced will gradually decrease with the prolongation of time, and when the titer of antibodies is very small or the antibodies have completely disappeared, there is a possibility of re-infection. Therefore, it is recommended to go to the hospital in time for examination, such as quantitative test of hepatitis B five items and antibody titer measurement, to determine whether the body still has hepatitis B protective antibody, if not, or the titer is less than 100IU/ml, it is recommended to replenish the vaccine in time, to avoid hepatitis B virus infection.