The HBsAg Test (historically known as the Australian Antigen test) is the primary blood test used to detect an active Hepatitis B virus (HBV) infection.
"HBsAg" stands for Hepatitis B Surface Antigen. This is a protein found on the surface of the Hepatitis B virus. If this protein is found in your blood, it means the virus is present in your body and you can spread the infection to others. It is the earliest marker of infection, often appearing even before symptoms start.
