Hepatitis B 245 positive suggests previous infection with hepatitis B and immunity to the hepatitis B virus, but the antibody titer may weaken with age, not necessarily lifelong immunity. Hepatitis B 245 positive refers to positive hepatitis B surface antibody, hepatitis B E antibody and hepatitis B core antibody in the hepatitis B five tests, suggesting that there has been a previous infection, which may be the result of hepatitis B vaccination or recent contact with hepatitis B patients, but the body has already cleared the virus and produced hepatitis B surface antibody, which can produce immunity to the hepatitis B virus in a longer period of time. However, with the prolongation of time, the concentration of hepatitis B surface antibody tends to decrease year by year, so it is difficult to achieve lifelong immunity. It is recommended to review the hepatitis B five tests regularly, if the antibody is obviously weakened or even disappeared, it is necessary to re-vaccinate hepatitis B vaccine to produce hepatitis B surface antibody again, so as to achieve the effect of lifelong immunization.