Positive hepatitis B core antibody after vaccination is generally not related to the vaccine itself, but is considered to be a previous infection with hepatitis B virus or the presence of hepatitis B virus. After hepatitis B vaccination, if the vaccination is effective, usually hepatitis B surface antibody will turn positive, but hepatitis B core antibody will not turn positive, so hepatitis B core antibody positive is not considered to be related to the vaccine itself. If a single hepatitis B core antibody is positive (mainly refers to hepatitis B core antibody IgG positive), it usually means that the patient has been infected with hepatitis B virus in the past, and the virus has been cleared from the body. If the hepatitis B core antibody is positive and the level of IgM antibody (protective antibody) is also high, it generally indicates that the hepatitis B virus exists in the body, and the hepatitis B virus is replicating and is infectious. Hepatitis B core antibody positivity should be analyzed together with surface antigen and E antigen to have clinical significance. It is recommended that the patient further identify the cause and follow the doctor’s instructions to standardize the treatment if necessary.