Positive HBs antigen in the absence of hepatitis B virus infection

TL;DR

This paper discusses the interpretation of positive HBs antigen results in hepatitis B screening, emphasizing the importance of clinical context and additional tests to distinguish between infection, vaccination, and false positives.

Contribution

It clarifies the interpretation of positive HBs Ag results without infection, highlighting the role of clinical context and confirmatory testing in diagnosis.

Findings

Positive HBs Ag can occur without HBV infection due to vaccination or false positives.

Clinical context and additional markers are essential for accurate interpretation.

Confirmatory tests and patient history improve diagnostic accuracy.

Abstract

French recommendations for the screening of hepatitis B virus (HBV) infection were updated in 2019 with the association of three markers: HBs Ag, anti-HBs Ab and anti-HBc Ab. These three markers allow identification of infected patients, vaccinated patients and patients who have been in contact with HBV. A positive HBs Ag is usually associated with HBV infection but this interpretation must take into account the clinical context. In particular, the absence of anti-HBc Ab, normal ALAT levels and the absence of jaundice can be associated with recent HBV vaccination or false-positive HBs Ag. Recent HBV vaccination can usually be confirmed by patient questioning, while confirmatory tests are useful to detect false positive HBs Ag. If necessary, a second sample can be requested to confirm the interpretation.