HBV PEP Protocol — MFDS Part 1 MCQ

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ModerateMicrobiologyHBV PEP ProtocolMFDS Part 1

An unvaccinated dental healthcare worker sustains a percutaneous needlestick injury from an instrument contaminated with blood from a patient known to be HBsAg positive. Which hepatitis B-specific post-exposure prophylaxis is indicated?

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Correct answer: B — An accelerated hepatitis B vaccination course plus HBIG with the first dose

This is a significant percutaneous exposure to blood from a known HBsAg-positive source, and the worker is unvaccinated. UKHSA guidance therefore recommends HBIG with the first dose of an accelerated hepatitis B vaccination course. The vaccine is given at 0, 1 and 2 months, with a further dose at 12 months if ongoing or likely future exposure risk remains. HBIG should be administered as soon as possible and vaccination must not be delayed while awaiting it. Vaccine alone is used for an unvaccinated person when the source is unknown, not when confirmed HBsAg positive. HBIG alone does not establish active immunity. A single booster applies to certain previously fully vaccinated individuals. Six-month HBsAg testing forms part of follow-up but is not a substitute for immediate prophylaxis.

Reference: UK Health Security Agency. Immunisation against infectious disease: The Green Book, Chapter 18, Hepatitis B, 'Other groups potentially exposed to hepatitis B' and Table 18.8, updated 2026. https://assets.publishing.service.gov.uk/media/66bb6f4749b9c0597fdb0eed/Hepatitis-B-green-book-chapter_18_20240813.pdf