A 28-year-old medical resident suffers an accidental deep needle-stick injury from a patient known to be positive for hepatitis B surface antigen (HBsAg). The resident completed the full hepatitis B vaccine series 4 years ago, but her current anti-HBs titer is 4 mIU/mL (< 10 mIU/mL). What post-exposure prophylaxis is required?

Answer and explanation

Correct answer: B. One dose of Hepatitis B Immune Globulin (HBIG) and a vaccine booster

  1. Step 1: Assess post-exposure risk: source patient is HBsAg positive.
  2. Step 2: A previously vaccinated individual whose current anti-HBs titer is inadequate (< 10 mIU/mL) is considered a non-responder or has waned antibody levels.
  3. Step 3: Standard occupational post-exposure protocols dictate immediate administration of HBIG (passive immunity) within 24 hours plus a single vaccine booster dose.
Answer
One dose of Hepatitis B Immune Globulin (HBIG) and a vaccine booster.
Why not the others: 'No treatment needed because immunological memory protects indefinitely' is inappropriate when antibody titer is documented below the protective threshold of 10 mIU/mL; 'Hepatitis B Immune Globulin (HBIG) monthly for 6 months without vaccination' is unnecessary and fails to stimulate active immunity; 'Oral tenofovir disoproxil fumarate daily for 28 days' is used in HIV prophylaxis, not primary HBV needle-stick protocol.

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