You can decide whether you need to take hepatitis B vaccine by taking blood test to check whether you have hepatitis B antibody in your body. 1. Situations requiring hepatitis B vaccination: if the results of hepatitis B 5 indicators are negative, it means that the body is not infected with hepatitis B, and there is no hepatitis B antibody in the body, so it is necessary to go to the hepatitis B vaccine in time to produce antibody to prevent hepatitis B effectively. 2. Situations that do not need to inject hepatitis B vaccine: if only the 2nd item of hepatitis B surface antibody is positive among the 5 indicators of hepatitis B, it means that the body has been injected with the vaccine and has already produced the antibody, the antibody titer can be further examined, and if it is greater than 100IU/L, this situation does not need to inject hepatitis B vaccine; if the body is already infected with hepatitis B, it generally does not need to inject the antibody, but it needs to be regularly rechecked. . It is recommended to go to the hospital for examination first and decide whether vaccination is needed under the guidance of the doctor.