In Hepatitis B vaccination, which serology marker indicates immunity?

• A. -HbsAB
• B. -HbsAG
• C. +HbsAB
• D. -HBeAG

Answer: (C)

The key idea is that protective immunity to hepatitis B is shown by detecting antibodies to the hepatitis B surface antigen (anti-HBs). After vaccination, the immune system makes these anti-HBs antibodies, and their presence at protective levels means the person is immune to hepatitis B. So a positive anti-HBs antibody indicates immunity.

The other markers tell different things. The surface antigen (HBsAg) indicates an active hepatitis B infection if present, not immunity. The presence of the e antigen (HBeAg) or its antibodies relates to viral replication and infectivity, not whether you’re protected by immunity. A negative anti-HBs means you are not immune.

Therefore, the marker that indicates immunity is the positive anti-HBs antibody.