If only anti-HBs is positive, which of the following can be ruled out?

If only anti-HBs is positive, which of the following can be ruled out?

• A. Hepatitis B virus vaccination
• B. Distant past infection with hepatitis B virus
• C. Hepatitis B immune globulin (HBIG) injection
• D. Chronic hepatitis B virus infection

Answer: (D)

When only anti-HBs is positive, this indicates the presence of antibodies against the hepatitis B surface antigen (HBsAg). The presence of anti-HBs typically occurs after recovery from an infection or following vaccination against hepatitis B. This means that it can be ruled out that the individual is currently experiencing a chronic hepatitis B virus infection. In chronic infections, HBsAg would be present, indicating an ongoing active hepatitis B infection, which would not correspond with the single positive anti-HBs result. In contrast, the other scenarios remain plausible. The individual could have been vaccinated against hepatitis B and developed the anti-HBs response. They could also have had a distant past infection, which has resolved, leading to the development of anti-HBs without any detectable HBsAg. Additionally, they could have received HBIG, which can provide passive immunity, but would not preclude the presence of anti-HBs depending on timing and individual immune response. Therefore, the presence of only anti-HBs confirms that chronic hepatitis B infection is not happening and allows for the other options to still be feasible.

When only anti-HBs is positive, this indicates the presence of antibodies against the hepatitis B surface antigen (HBsAg). The presence of anti-HBs typically occurs after recovery from an infection or following vaccination against hepatitis B. This means that it can be ruled out that the individual is currently experiencing a chronic hepatitis B virus infection. In chronic infections, HBsAg would be present, indicating an ongoing active hepatitis B infection, which would not correspond with the single positive anti-HBs result.

In contrast, the other scenarios remain plausible. The individual could have been vaccinated against hepatitis B and developed the anti-HBs response. They could also have had a distant past infection, which has resolved, leading to the development of anti-HBs without any detectable HBsAg. Additionally, they could have received HBIG, which can provide passive immunity, but would not preclude the presence of anti-HBs depending on timing and individual immune response.

Therefore, the presence of only anti-HBs confirms that chronic hepatitis B infection is not happening and allows for the other options to still be feasible.