A 24-year-old healthcare worker undergoes routine hepatitis B screening before posting to the dialysis unit. Results: HBsAg negative, anti-HBs positive (45 mIU/mL), anti-HBc total negative, HBeAg negative. What does this profile indicate?
- A Immunity from vaccination ✓
- B Past hepatitis B infection with recovery
- C Chronic hepatitis B infection
- D Window period of acute infection
Correct answer: A. Immunity from vaccination
Explanation
Anti-HBs without anti-HBc indicates vaccine-derived immunity, because the recombinant vaccine contains only HBsAg and never generates antibody to core antigen. Past natural infection produces both anti-HBs and anti-HBc, which kills option B. The window period shows anti-HBc IgM positivity with HBsAg negative but anti-HBs also negative, so D fails on two counts. Chronic infection requires a positive HBsAg.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.