Post-exposure prophylaxis for influenza — MSRA MCQ

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ModerateInfectious DiseasesPost-exposure prophylaxis for influenzaMSRA

A 77-year-old man contacts his GP for advice. His wife, with whom he shared a bedroom until yesterday evening, has PCR-confirmed influenza A. He is asymptomatic. Influenza is circulating in the community. He has stage 4 chronic kidney disease with stable renal function; his calculated creatinine clearance is 27 mL/minute. He received this season’s influenza vaccine 8 days ago. He has no drug allergies and can take oral medication. What is the most appropriate management now?

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Correct answer: A — Start oseltamivir 30 mg orally every 48 hours for 10 days

Explanation lettering: C = shown as A · D = shown as B · B = shown as C · A = shown as D

He should receive post-exposure antiviral prophylaxis with oseltamivir 30 mg every 48 hours for 10 days. He has had close household exposure to confirmed influenza, is at increased risk of severe influenza because of both age and chronic renal disease, and is not yet adequately protected by vaccination because exposure occurred fewer than 14 days after vaccination. Prophylaxis can be started within 48 hours of last exposure. For post-exposure prophylaxis, the standard adult course is oseltamivir once daily for 10 days, but renal adjustment is required. With a creatinine clearance of 11–30 mL/minute, the SmPC-recommended prophylactic dose is 30 mg every second day. A is the usual dose for creatinine clearance above 60 mL/minute. B is the renal-adjusted prophylactic dose for creatinine clearance 31–60 mL/minute. D applies a treatment-duration regimen to an asymptomatic contact and also gives an incorrect prophylactic frequency for this renal function. E overlooks that influenza vaccine protection has not had sufficient time to develop.

Reference: Guidance on use of antiviral agents for the treatment and prophylaxis of seasonal influenza (Updated 23 January 2026) — https://www.gov.uk/government/publications/influenza-treatment-and-prophylaxis-using-anti-viral-agents/guidance-on-use-of-antiviral-agents-for-the-treatment-and-prophylaxis-of-seasonal-influenza Guidance on use of antiviral agents for the treatment and prophylaxis of seasonal influenza (Updated 23 January 2026) — https://www.gov.uk/government/publications/influenza-treatment-and-prophylaxis-using-anti-viral-agents/guidance-on-use-of-antiviral-agents-for-the-treatment-and-prophylaxis-of-seasonal-influenza Oseltamivir 30 mg Hard Capsules: Summary of Product Characteristics (Last updated 29 January 2024) — https://www.medicines.org.uk/emc/product/14724/smpc