Reviewed on : 9 Oct 2024

Reviewed by : (Lisa Berry Consultant Virologist)& Gateway Editor

Expires : 9 Oct 2026

Background

Chicken pox (varicella) infection in neonates, immunosuppressed individuals and pregnant women can result in severe and even life-threatening varicella disease.

To attenuate disease and reduce the risk of complications such as pneumonitis, post-exposure prophylaxis (PEP) with varicella-zoster specific immunoglobulin (VZIG) was the standard of care up until 2018

Complications of chicken pox in pregnancy include severe maternal varicella and congenital varicella syndrome

See UKHSA Guidelines on post exposure prophylaxis for varicella or shingles and the Varicella Green Book chapter

Contact with VZV should be managed promptly as follows:

• Past history of chicken pox, shingles or 2 documented doses of varicella vaccine: Reassure, no action required.

If immunosuppressed, please call virology to discuss

• No / Uncertain Reliable Past History: Need to ascertain if significant exposure

This depends on:

1)The type of VZ infection in the index case (chicken pox, zoster on an exposed site, zoster on any site in an immunocompromised individual, or disseminated zoster all present a risk; non-exposed zoster in an immunocompetent individual is not a risk as long there has not been any exposure to uncovered lesions)

2)The timing of exposure in relation to onset of rash:

• Infectious period is 48 hours before onset of rash to crusting of lesions in chicken pox or disseminated shingles
• Day of onset of rash to crusting of lesions in localised shingles

3)The closeness and duration of contact (continuous contact at home, multiple contacts with the infected individual, contact in the same room for 15 minutes or more and face to face contact are all considered a risk)

If there is no history of chicken pox AND the exposure was significant then test for immunity by sending a serum sample for VZV IgG

Provide as many relevant details as possible, including date and nature of contact and weeks of gestation. This helps to ascertain urgency

Phone the laboratory if possible so that we can look out for the sample: 024 7696 5468. Alternatively, it can be arranged for VZV IgG testing to be performed on antenatal booking bloods if available, please telephone the laboratory to request this

If the patient is susceptible (IgG levels <100 IU/ml for immunocompetent pregnant women), post-exposure prophylactic antivirals can be offered:

October 2024 Update

Antivirals are now recommended for post-exposure prophylaxis for all at risk groups including pregnant women, immunosuppressed individuals, and susceptible neonates

• In addition, for neonates designated in Group 1 i.e. those exposed to their mother (in utero or post-delivery) within one week of onset of chicken pox in the mother) the antiviral treatment should be supplemented with intravenous (i.v.) varicella immunoglobulin either as a hyperimmune product (i.e. Varitect CP) (which can be obtained via the Duty Doctor/RIGS team in the same way that VZIG was) or normal intravenous immunoglobulin (IVIG) (which NHS trusts will have ready access to)
• A bolus dose of IVIG may also be considered for eligible groups for whom oral antivirals are contraindicated
  

  Post exposure prophylaxis (PEP) is offered to individuals at high risk of severe chickenpox following an exposure

Oral aciclovir 800mg four times a day from days 7 to 14 after initial exposure is recommended

Oral valaciclovir 1000mg three times a day can be used as a suitable alternative

If contact was continuous e.g. household member, prophylaxis should be commenced 7 days post onset of rash in the index case. If the woman presents later than day 7 after exposure, a 7 day course of antivirals can be started up to day 14 after exposure, if necessary

Please ensure that the patient’s Obstetrics team are aware of the contact – particularly if she develops chicken pox despite prophylaxis, or demonstrates seroconversion

Women who have a second exposure during pregnancy should be risk assessed and have a repeat VZV antibody test, and may be re-offered prophylaxis if non-immune

Given the shorter half-life of antivirals, compared with VZIG, if there is a second exposure immediately after completion of the course of antivirals, a second risk assessment should be performed and a further course of antivirals should be given in the same way, starting 7 days after the subsequent exposure

Please advise the patient to keep away from other pregnant women and immunocompromised individuals from 8 to 28 days after exposure. This would include sitting in a waiting room for a clinic appointment

Chicken pox can occur despite prophylaxis, particularly where the index case was a household contact. Consider prompt treatment with oral aciclovir. Although the disease may be attenuated, severe infection may still occur

For advice please contact the Duty Virology Team at UHCW on 024 7696 5471 or 5349