Description

A hepatitis B surface antibody (HBsAb) test measures the amount of antibodies in your blood that your immune system produces to fight the hepatitis B virus (HBV): 

Purpose: Determines if you are immune to HBV after vaccination or natural exposure.

Results: A positive result means you are immune, while a negative result means you are not immune. 

When it's used: For people who have been vaccinated, or who have had an infection and cleared the virus

Fasting not required