Final answer:
HBsAg (hepatitis B surface antigen) indicates an active infection with the hepatitis B virus (HBV). It is a marker of HBV infection and can be detected in the blood of infected individuals. Vaccination against HBV is available and recommended to prevent infection and its complications.
Step-by-step explanation:
The presence of HBsAg (hepatitis B surface antigen) indicates an active infection with the hepatitis B virus (HBV). HBsAg is a protein found on the surface of the virus and is the first antigen to appear during infection. It is a marker of HBV infection and can be detected in the blood of infected individuals.
HBsAg-positive individuals can transmit the virus to others through blood, semen, or other body fluids. However, not all HBsAg-positive individuals will develop symptoms or long-term complications. Some may clear the infection on their own, while others may progress to chronic hepatitis B.
Vaccination against HBV is available and recommended to prevent infection and its complications.