What does the presence of anti-HBs or HBsAb indicate?

The presence of anti-HBs, also known as hepatitis B surface antibodies or HBsAb, indicates that a person has developed immunity to hepatitis B. This can occur as a result of either recovery from a past hepatitis B infection or due to vaccination against the virus. Essentially, the presence of these antibodies signifies that the immune system has successfully recognized and responded to the hepatitis B surface antigen, leading to protective immunity.

In contrast, the other options relate to different scenarios regarding hepatitis B. A current infection would generally be indicated by the presence of hepatitis B surface antigen (HBsAg) rather than anti-HBs. Chronic hepatitis B is characterized by ongoing presence of HBsAg, not antibodies. Additionally, while having a history of hepatitis B might suggest prior infection, the presence of anti-HBs specifically signifies immunity, not merely the existence of a past infection. Thus, the presence of anti-HBs directly correlates with acquired immunity to hepatitis B, which is the defining feature of this result.