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Post-exposure prophylaxis following sexual exposure to acute hepatitis B in pregnancy — DFSRH MCQ

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EasyHepatitis BPost-exposure prophylaxis following sexual exposure to acute hepatitis B in pregnancyDFSRH

A 31-year-old woman attends a sexual health clinic at 10 weeks’ gestation. Five days ago, she had unprotected vaginal intercourse with her regular male partner. He has since developed jaundice and has been diagnosed with acute hepatitis B: HBsAg and anti-HBc IgM are positive. She has never received hepatitis B vaccination and has no history of hepatitis B infection or vaccine allergy. Her antenatal hepatitis B screening result is not yet available. Which is the most appropriate immediate management?

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Correct answer: C — Take baseline hepatitis B serology and give HBIG with the first accelerated hepatitis B vaccine dose immediately

Unprotected intercourse is a significant hepatitis B exposure. The source has laboratory-confirmed acute infection, which carries a higher transmission risk than established chronic infection, and the patient is unvaccinated. Because she presents within one week of her last sexual contact, UKHSA guidance recommends both hepatitis B immunoglobulin (HBIG), providing immediate passive protection, and hepatitis B vaccine, providing active immunity. HBIG should be administered as soon as possible at a different injection site from the vaccine. The vaccine course should continue using the post-exposure accelerated schedule at 0, 1 and 2 months. Baseline HBsAg, anti-HBc and anti-HBs testing is appropriate, but neither vaccination nor HBIG should be delayed while results are awaited because the useful post-exposure window is time limited. Pregnancy is not a reason to postpone vaccination: hepatitis B vaccines are inactivated, and UK guidance states that they may be given safely during pregnancy when exposure risk is high. A delays time-critical prophylaxis. B omits indicated passive protection; vaccine alone would apply if more than one week had elapsed since the last contact. D incorrectly treats the first trimester as a vaccine contraindication. E risks missing the HBIG window while awaiting serology. She should also use condoms until after the third vaccine dose and be offered follow-up testing for infection.

Reference: Immunisation against infectious disease: Hepatitis B, Chapter 18 (5 February 2026) — https://assets.publishing.service.gov.uk/media/699c8d35e1c6bad1576fbc01/Green-book-on-immunisation-hepatitis-B-chapter_-_05022026.pdf Immunisation against infectious disease: Hepatitis B, Chapter 18 (5 February 2026) — https://assets.publishing.service.gov.uk/media/699c8d35e1c6bad1576fbc01/Green-book-on-immunisation-hepatitis-B-chapter_-_05022026.pdf Hepatitis B immunoglobulin (31 July 2026) — https://www.gov.uk/government/publications/immunoglobulin-when-to-use/hepatitis-b-immunoglobulin-issued-march-2021