Clinical Algorithm

Post-exposure prophylaxis for pregnant women exposed to VZV

Click through the pathway. This is an educational decision aid — always follow your local hospital policy and the guideline version in use.

Step 1 of 3 — Exposure history Your selection: —
Maternal history of varicella zoster
OR two documented doses of varicella vaccine
Assume immune
No need for post-exposure prophylaxis. Reassure.
End of pathway
Test VZV IgG
Use antenatal booking bloods (if available) for VZV IgG.
Select result
* If repeated exposure occurs within the same pregnancy and serology shows non-immunity, consider repeat VZV IgG and follow local policy (including if VZIG/antivirals were given).
Immune / reassuring result
No need for post-exposure prophylaxis. Reassure.
End of pathway
Non-immune (or low IgG)
  • Aciclovir 800 mg four times daily for 7 days.
  • Start on day 7 after exposure (can be started up to day 14).
  • VZIG can be used as an alternative if required (per local policy).
Use local prescribing guidance (renal impairment, interactions, documentation, and counselling).
Clinical pathway end
Disclaimer: Educational tool for clinicians. Always follow local hospital policy and the guideline version in use.

QUICK FACTS

Varicella (Chickenpox) in Pregnancy

Irish Guideline

    • Pregnant women

    • Women up to 6 weeks after delivery

    • Based on the Irish National Clinical Guideline (2023).

    • Educational summary only — follow local hospital policy.

    • Check immunity at booking

    • Immune if:

      • Previous chickenpox or shingles

      • Two doses of varicella vaccine

      • Positive VZV IgG

    • Varicella vaccine:

      • Not given in pregnancy

      • Offered after delivery if non-immune

    • Assess:

      • Immunity status

      • Type and timing of exposure

    • If immunity unclear:

      • Check VZV IgG

    • Advise review if rash or fever develops within 3–4 weeks

    • Oral aciclovir is first choice

    • Start:

      • Day 7 after exposure

      • Up to day 14

    • VZIG may be used in selected cases

    • Isolate if admitted

    • Start aciclovir early

    • Use IV aciclovir for severe disease

    • Involve senior obstetric team

    • Routine fetal review not needed if mother asymptomatic

    • Refer to Fetal Medicine if infection occurs in pregnancy

    • Shingles is not linked to fetal varicella syndrome

    • Breastfeeding is safe

    • Aciclovir is safe during breastfeeding

  • Irish National Clinical Practice Guideline:
    Varicella in Pregnancy – HSE & IOG, October 2023.