Which serologic marker indicates immunity to Hepatitis B?

The presence of HBsAb, or Hepatitis B surface antibodies, indicates immunity to Hepatitis B. This immunity can be a result of either recovery from a past Hepatitis B infection or as a consequence of vaccination against the virus. When a person has a positive HBsAb result, it confirms that their immune system has successfully responded to either the natural infection or the vaccine, producing antibodies that protect against future infections.

In contrast, HBsAg (Hepatitis B surface antigen) being positive indicates an active Hepatitis B infection, meaning the virus is present in the body, and the individual is not immune. Similarly, HBcAb (Hepatitis B core antibody) positive indicates a past or current infection but does not directly reflect immunity. Lastly, Anti-HCV positivity relates to Hepatitis C virus exposure and does not provide any information regarding immunity to Hepatitis B. Therefore, the marker that specifically signifies immunity is HBsAb positive.