Which condition is associated with a negative Hepatitis B surface antibody?

A negative Hepatitis B surface antibody (anti-HBs) indicates that the individual does not have immunity against Hepatitis B, which is often associated with a chronic infection. In individuals with chronic Hepatitis B infection, the virus persists in the body, and as a result, the immune system has not mounted an effective response that would lead to the production of antibodies to the Hepatitis B surface antigen (HBsAg).

In contrast, individuals who have had vaccination or have achieved natural immunity after clearing an acute infection typically have positive anti-HBs, indicating they have developed immunity. During an acute infection, it is possible for individuals to also have a negative anti-HBs until the infection resolves and the immune response has had time to generate the necessary antibodies. Therefore, the absence of the surface antibody would suggest a scenario related to chronic infection rather than successful vaccination or recovery from an acute infection.