What Does a Negative Hepatitis B Surface Antigen Result Mean?

A negative hepatitis B surface antigen (HBsAg) test result generally indicates that the individual is not currently infected with the hepatitis B virus (HBV). However, for a more accurate interpretation, it is recommended to evaluate the result alongside the other four markers in the hepatitis B panel.

There are typically two possible explanations for a negative HBsAg result — either the person has never been exposed to the hepatitis B virus, or they were previously infected and their immune system successfully cleared the virus, leading to a loss of HBsAg. In such cases, additional tests are necessary to determine the exact situation, especially if there is a possibility of past exposure.

HBsAg is a protein found on the surface of the hepatitis B virus. When this antigen is present in the blood, it indicates an active HBV infection. Although HBsAg itself is not infectious, it is a key immunological marker of hepatitis B infection and is commonly used in diagnostic testing.

Following exposure to the hepatitis B virus, HBsAg can be detected in the blood within a few weeks. In cases of acute, self-limiting hepatitis B infection, HBsAg usually disappears within 12 to 20 weeks. However, in individuals who become chronic carriers or develop chronic hepatitis B, the surface antigen may persist for many years or even for life. This is particularly important for long-term monitoring and management of the disease.