What does “HBsAg negative” mean?

HBsAg (hepatitis B surface antigen) is a marker of hepatitis B virus (HBV) infection. While HBsAg itself is non-infectious, its presence indicates current or past HBV infection. Further testing—including liver function tests, quantitative HBV DNA assay, and abdominal ultrasound—can help assess disease status and guide clinical management, such as antifibrotic or antiviral therapy. So, what does “HBsAg-negative” mean? Below is an explanation.

What Does “HBsAg-Negative” Mean?

HBsAg stands for hepatitis B surface antigen—the most commonly used laboratory test to screen for HBV infection. A positive HBsAg result indicates current HBV infection and infectiousness, warranting further evaluation—including liver function tests, quantitative HBV DNA measurement, and hepatic ultrasound—to determine disease severity and whether antiviral therapy is indicated. An HBsAg-negative result generally suggests either no prior HBV infection or successful viral clearance following resolved infection. However, caution is warranted: a small subset of individuals may test HBsAg-negative yet show positivity for other markers in the “five-item HBV serology panel” (e.g., anti-HBc or anti-HBs), along with detectable HBV DNA—indicating persistent occult HBV infection (OBI). In such cases, HBsAg negativity may reflect viral mutations that impair antigen expression; referral to a specialized hepatology center is recommended for definitive diagnosis and management.

Knowledge Extension: Routes of Transmission

1. Transmission via Blood Transfusion

Blood components and derivatives from donors who are HBsAg-negative but HBV DNA-positive must be considered potentially infectious. Due to the lack of universal implementation of anti-HBc screening and nucleic acid testing (NAT), transmission of HBV from donors with occult HBV infection (OBI) remains a significant public health concern. Moreover, because the minimal infectious dose of HBV is lower than the detection limit of current HBV DNA assays, there remains an extremely low—but non-zero—risk of transfusion-transmitted OBI.

2. Liver Transplantation

Liver grafts from donors with occult HBV infection can transmit HBV to HBV-naïve recipients. Therefore, recipients of such organs should receive lifelong nucleos(t)ide analogue therapy to prevent HBV reactivation or de novo infection.

3. Mother-to-Child Transmission

Even when newborns receive appropriate active or passive immunoprophylaxis at birth, infants born to HBsAg-positive mothers remain at risk for developing occult HBV infection.

The above outlines the meaning of “HBsAg-negative.” We hope this information is helpful to you.