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Varicella exposure in pregnancy with inability to take oral antivirals — MSRA MCQ

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HardInfectious DiseasesVaricella exposure in pregnancy with inability to take oral antiviralsMSRA

A 30-year-old woman at 15 weeks’ gestation reports that her 5-year-old daughter developed chickenpox 6 days ago. They live together and have had continuous close contact. The woman has no history of chickenpox, shingles or varicella vaccination. She remains afebrile and has no rash. Testing of her booking serum shows a quantitative varicella-zoster virus IgG concentration of 24 mIU/mL. She is currently an inpatient with refractory hyperemesis gravidarum. Despite intravenous fluids and antiemetics, she cannot retain oral fluids or medication, and the obstetric team expects this to continue for at least another week. Which is the most appropriate post-exposure management?

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Correct answer: B — Arrange normal intravenous immunoglobulin 0.2 g/kg today

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

She meets all three criteria for varicella post-exposure prophylaxis: continuous household exposure, pregnancy with consequent risk of severe disease, and confirmed susceptibility because her quantitative VZV IgG is below 100 mIU/mL. For a household contact, exposure is dated from the index case’s rash onset, placing her on day 6. Oral aciclovir or valaciclovir, normally given from days 7 to 14, is first-line for susceptible pregnant contacts. However, she cannot retain oral medication and this is expected to persist throughout the antiviral window. Current UKHSA guidance states that contacts unable to receive oral antivirals should instead receive normal IVIG 0.2 g/kg, ideally within 10 days of first contact; it should therefore be arranged now. A omits indicated prophylaxis in a susceptible high-risk contact. B would be standard if she could reliably absorb oral treatment, but is unsuitable during refractory hyperemesis. D confuses prophylaxis with treatment: intravenous aciclovir is considered for severe established chickenpox, not the recommended substitute for oral PEP in an asymptomatic pregnant contact. E is attractive because it is varicella-specific immunoglobulin, but Varitect CP is reserved for specified high-risk neonatal exposures; normal IVIG is the recommended immunoglobulin for other contacts unable to receive antivirals.

Reference: Guidelines on post-exposure prophylaxis (PEP) for varicella or shingles (19 March 2026) — https://www.gov.uk/government/publications/post-exposure-prophylaxis-for-chickenpox-and-shingles/guidelines-on-post-exposure-prophylaxis-pep-for-varicella-or-shingles-january-2023