Hepatitis B Surface Antibody, Quantitative Unit Converter

Hepatitis B surface antibody (anti-HBs or HBsAb) is a protein produced by your immune system in response to the hepatitis B virus surface antigen. It indicates immunity to hepatitis B infection.

Your body can develop these antibodies in two ways: after recovering from a natural hepatitis B infection, or after successful vaccination against the virus. In either case, the presence of anti-HBs signals that you are protected from future hepatitis B infection.

A level of 10 mIU/mL or greater is generally considered protective. This test cannot distinguish between vaccine-induced immunity and immunity from past infection. To make that distinction, testing for hepatitis B core antibody (anti-HBc) is needed.

Anti-HBs is produced by B cells (a type of white blood cell) as part of the adaptive immune response. These antibodies are generated either after exposure to the hepatitis B virus surface antigen during a natural infection, or after vaccination with recombinant HBsAg.