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Medical Emergencies · single question

What is anti-HBs (antibody to Hepatitis B surface antigen) POSITIVE result indicate?

  1. Immune — either from vaccination or past infection with recovery
  2. Active Hepatitis B infection
  3. Chronic Hepatitis B infection
  4. Carrier state
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Correct answer: A. Immune — either from vaccination or past infection with recovery

  • A. Correct. Anti-HBs POSITIVE means the patient has ANTIBODIES against HBV surface antigen — indicating IMMUNITY, either from: (1) VACCINATION (the HBV vaccine produces anti-HBs), or (2) RECOVERY from past infection (natural immunity). Anti-HBs positive = protective immunity.
  • B. Incorrect. ACTIVE infection is indicated by HBsAg (surface antigen) POSITIVE — not anti-HBs.
  • C. Incorrect. CHRONIC hepatitis B is also HBsAg positive — anti-HBs is NOT present because the immune system has not cleared the virus.
  • D. Incorrect. The CARRIER STATE is indicated by HBsAg positive for >6 months with negative anti-HBs.

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