Hepatitis B Surface Antibody Total (Anti-HBs) Test :
A blood test that measures the total level of antibodies to the Hepatitis B surface antigen (HBsAg). The presence of Anti-HBs indicates immunity to Hepatitis B, which can be due to either previous infection or vaccination . A positive result suggests that the person is protected against future infection with the virus. The test is commonly used to assess immunity status after vaccination or to determine if a person has cleared a prior Hepatitis B infection.