Hepatitis B Immunity (HBsAb) Test - Hepatitis B Surface Antibody Test (HBsAb)

This test measures the titer (quantity) of antibodies directed against the hepatitis B virus surface antigen (HBsAg), also known as Anti-HBs or HBs Ab. These antibodies appear after successful vaccination or after recovery from acute hepatitis B infection. These antibodies neutralize the virus and prevent it from infecting liver cells, thus providing protective immunity. It is used to assess the immune response to vaccination and evaluate the need for a booster dose.