A patient has HBsAg negative, anti-HBs positive and anti-HBc negative. What does this pattern show?
Answer and explanation
Correct answer: C. Immunity from vaccination without past infection
- Step 1: HBsAg negative means no current infection, and anti-HBs positive means protective antibody. Step 2. Anti-HBc is a marker of exposure to the virus and is absent after vaccination alone. Answer: Vaccine-induced immunity. Why not the others: A window period shows anti-HBc IgM. Chronic infection is HBsAg positive. Natural recovery gives positive anti-HBc.
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