Interpretation of Hepatitis B Serologic Test Results
The laboratory results indicate immunity to hepatitis B virus (HBV) from vaccination, not from natural infection. The hepatitis B surface antibody (anti-HBs) level of 2506.0 mIU/mL is well above the protective threshold of 10 mIU/mL, while the negative hepatitis B surface antigen (HBsAg) and negative hepatitis B core antibody (anti-HBc) confirm absence of current or past infection 1.
Interpretation of Individual Test Results
- Hepatitis B Surface Antibody (Anti-HBs) = 2506.0 mIU/mL: This is significantly above the protective threshold of 10 mIU/mL, indicating strong immunity to HBV 1.
- Hepatitis B Surface Antigen (HBsAg) = Negative: Indicates no current HBV infection 1.
- Hepatitis B Core Antibody (Anti-HBc IgM) = Negative: Indicates no acute or recent HBV infection 1.
Pattern Interpretation
- HBsAg negative + Anti-HBc negative + Anti-HBs positive: This pattern specifically indicates immunity from vaccination rather than from natural infection 1.
- The absence of hepatitis B core antibodies confirms that immunity was acquired through vaccination and not through resolved natural infection 1, 2.
- The very high anti-HBs level (2506.0 mIU/mL) suggests either recent vaccination or a robust immune response to previous vaccination 1.
Clinical Significance
- Protective Immunity: Anti-HBs levels ≥10 mIU/mL are considered protective against HBV infection 1, 3.
- Long-term Protection: Immunocompetent persons with anti-HBs ≥10 mIU/mL after completing the vaccine series have long-term protection and do not need further periodic testing to assess anti-HBs levels 1.
- No Need for Booster: Current evidence indicates that vaccine-induced immunity provides long-term protection even if antibody levels decline over time, due to immunologic memory 3.
Important Considerations
- This pattern of test results (negative HBsAg, negative anti-HBc, positive anti-HBs) definitively distinguishes vaccine-derived immunity from immunity acquired through natural infection 1.
- The extremely high anti-HBs level (2506.0 mIU/mL) is well above what is considered protective (>10 mIU/mL) and indicates robust vaccine response 1.
- For immunocompetent individuals with documented completion of the hepatitis B vaccine series and anti-HBs ≥10 mIU/mL, no further testing or booster doses are currently recommended 1.
Potential Pitfalls to Avoid
- Do not confuse vaccine-induced immunity with resolved infection. In resolved infection, both anti-HBs and anti-HBc would be positive 2.
- Very low levels of anti-HBs (2-10 mIU/mL) may sometimes require clinical correlation, but this patient's level is far above this range 4.
- False-positive anti-HBc results can occur, but this is not relevant here as the anti-HBc is negative 5.
In summary, these laboratory results demonstrate successful immunization against hepatitis B virus with a robust antibody response, providing protection against future infection 1.