A serum sample is positive for HBsAg. This result indicates that the person from whom the serum was taken

A serum sample is positive for HBsAg. This result indicates that the person from whom the serum was taken

• A. Had a hepatitis B infection in the past but overcame the infection.
• B. Has either active or chronic hepatitis B infection.
• C. Was immunized recently against the hepatitis B virus (HBV).
• D. Is not infectious for the HBV.

Answer: (B)

HBsAg, the hepatitis B surface antigen, is a marker of active HBV infection. Its presence in serum means the person currently harbors the virus and can be infectious, whether the infection is acute or chronic. In contrast, someone who had a past infection and cleared it would no longer have HBsAg and would typically have anti-HBs (and possibly anti-HBc). Immunization creates anti-HBs without HBsAg, and a statement that the person is not infectious conflicts with the detection of the viral surface antigen.

HBsAg, the hepatitis B surface antigen, is a marker of active HBV infection. Its presence in serum means the person currently harbors the virus and can be infectious, whether the infection is acute or chronic. In contrast, someone who had a past infection and cleared it would no longer have HBsAg and would typically have anti-HBs (and possibly anti-HBc). Immunization creates anti-HBs without HBsAg, and a statement that the person is not infectious conflicts with the detection of the viral surface antigen.