Hepatitis B surface antibodies (anti-HBs) are protective antibodies; a positive test indicates immunity to hepatitis B virus (HBV), while a negative test indicates no immunity to HBV. Hepatitis B surface antibodies begin to appear in the late stage of acute infection, some time after the hepatitis B surface antigen (HBsAg) turns negative, and gradually rise to a peak within 6 to 12 months, which can last for many years, but the titer will gradually decrease; in about half of the cases, hepatitis B surface antibodies can be detected several months after the hepatitis B surface antigen turns negative; in a few cases, hepatitis B surface antibodies are never produced after the hepatitis B surface antigen turns negative. Positive hepatitis B surface antibodies indicate immunity to the hepatitis B virus and are seen in recovery from hepatitis B, previous infection, and after hepatitis B vaccination. A weakly positive hepatitis B surface antibody may be the result of a previous infection with the hepatitis B virus, or a hepatitis B vaccination that has given immunity, but the hepatitis B antibody titer has gradually decreased over time, hence the weakly positive hepatitis B surface antibody. There is no need to monitor antibody titers for the general population. For high-risk groups (e.g., those in close contact with hepatitis B virus-infected persons, medical workers, drug addicts, etc.), antibody titers should be tested regularly after hepatitis B vaccination. When antibody titers are less than 10 IU/mL, hepatitis B vaccination should be replenished in time to ensure that hepatitis B surface antibodies in the body maintain effective titers for a long time, so as to truly prevent hepatitis B virus infection.