What indicates a carrier state in Hepatitis B?

A carrier state in Hepatitis B is characterized by the presence of Hepatitis B surface antigen (HBsAg) in the blood. When HBsAg is positive, it indicates that an individual is currently infected with the virus, and they can potentially transmit it to others. This state can persist for an extended period, sometimes for life, leading to what is referred to as a chronic Hepatitis B infection or chronic carrier state.

Having a positive HBsAg signifies active viral replication and ongoing infection, differentiating it from other serological markers which indicate either recovery from infection or vaccination. For example, a negative HBsAg would indicate that the virus is no longer present, while positive anti-HBs would suggest recovery from the infection or successful vaccination, neither of which would indicate a carrier state. Similarly, positive anti-HBc indicates past or ongoing infection, but does not in itself confirm that a carrier state exists without the presence of HBsAg. Thus, the crucial marker for indicating a carrier state is a positive HBsAg.