Hepatitis B Surface Antibody Reactive Result Interpretation
A reactive (positive) Hepatitis B surface antibody (anti-HBs) result indicates immunity to Hepatitis B virus (HBV), either from successful vaccination or from recovery from a previous HBV infection. 1
Understanding Anti-HBs Results
- A reactive anti-HBs test (typically ≥10 mIU/mL) indicates the presence of protective antibodies against the Hepatitis B surface antigen (HBsAg) 1
- Anti-HBs is the only serological marker that indicates protective immunity against HBV infection 2
- This immunity can be acquired through:
Complete Interpretation Requires Additional Testing
- To fully understand the clinical significance of a reactive anti-HBs result, additional serological markers should be considered 1:
Clinical Significance
- A reactive anti-HBs result generally indicates protection against future HBV infection 1, 2
- The presence of anti-HBs at levels ≥10 mIU/mL is considered protective against HBV infection 1
- Individuals with reactive anti-HBs results do not require vaccination against HBV 1
- Those with immunity from resolved infection (anti-HBc positive + anti-HBs positive) are generally not at risk for developing chronic HBV infection 3
Important Considerations and Pitfalls
- Rarely, anti-HBs may be passively acquired through recent blood product transfusion and may not represent true immunity 4
- Individuals with resolved HBV infection (anti-HBc positive + anti-HBs positive) may be at risk for HBV reactivation if they become immunosuppressed, particularly with treatments like anti-CD20/CD52 monoclonal antibodies or high-dose corticosteroids 3
- The risk of reactivation in HBsAg-negative but anti-HBc-positive patients ranges from 3-45% when receiving immunosuppressive therapy 3
- Anti-HBs levels may naturally increase (boost) upon re-exposure to HBV in previously immunized individuals, indicating continued vaccine effectiveness 5
Management Implications
- For immunocompetent individuals with reactive anti-HBs, no specific treatment or additional vaccination is needed 3, 1
- For patients requiring immunosuppressive therapy who have evidence of past HBV infection (anti-HBc positive), HBV DNA testing is recommended before starting therapy 3
- Monitoring of liver function tests during immunosuppressive therapy may be warranted in patients with evidence of past HBV infection 3