Hepatitis B Serology Interpretation: Positive Anti-HBs with Negative Anti-HBc, HBsAg, and IgG Anti-HBc
This serologic pattern (HBsAg negative, total anti-HBc negative, IgM anti-HBc negative, anti-HBs positive) indicates immunity from hepatitis B vaccination, not natural infection—the answer is C: Vaccinated. 1
Definitive Interpretation Based on CDC Guidelines
Persons who respond to hepatitis B vaccine are positive only for anti-HBs, whereas persons who recover from natural HBV infection are typically positive for both anti-HBs and anti-HBc. 1 This fundamental distinction allows clear differentiation between vaccine-derived immunity and immunity from past infection.
The complete serologic pattern breaks down as follows:
- Negative HBsAg: Rules out current infection (both acute and chronic) 1
- Negative total anti-HBc: Rules out any past or present HBV infection 1
- Negative IgM anti-HBc: Further confirms no acute infection 1
- Positive anti-HBs: Indicates protective immunity 1, 2
Why Other Options Are Incorrect
Option A (Acute Infection) - Definitively Excluded
Acute HBV infection requires HBsAg positive, total anti-HBc positive, and IgM anti-HBc positive. 1 This patient has none of these markers.
Option B (Chronic Infection) - Definitively Excluded
Chronic HBV infection requires HBsAg positive and total anti-HBc positive, with negative IgM anti-HBc. 1 The absence of both HBsAg and anti-HBc completely rules this out.
Option D (Previous Infection) - Definitively Excluded
Recovered from past infection requires HBsAg negative, total anti-HBc positive, and anti-HBs positive. 1 The critical distinguishing feature is that natural infection always leaves behind anti-HBc, which persists for life. 1 This patient lacks anti-HBc entirely.
Clinical Significance and Protection Status
If the anti-HBs concentration is ≥10 mIU/mL, this patient has protective immunity against HBV infection. 1 The CDC guidelines confirm that immunocompetent persons who achieve this threshold after completing the vaccine series have long-term protection that persists for 30 years or more, likely for life, even when antibody levels subsequently decline. 3
Important Caveats to Avoid Misinterpretation
Anti-HBs can be detected for 4-6 months following hepatitis B immune globulin (HBIG) administration, which represents passive transfer rather than true immunity. 1, 2 However, this scenario would be evident from the clinical history of recent HBIG administration.
Transient HBsAg positivity can occur up to 18 days following vaccination and is clinically insignificant. 1, 2 This does not affect the interpretation of anti-HBs positivity with negative anti-HBc.
No Further Action Required
For immunocompetent individuals with this serologic pattern who have documented completion of the hepatitis B vaccine series, no further testing or booster doses are currently recommended. 3 The presence of anti-HBs alone definitively indicates vaccine-derived immunity and requires no additional management. 2