Complications of chicken pox in pregnancy include severe maternal varicella and congenital varicella syndrome.
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:
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)
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.
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 prophylaxis can be offered:
If <20 weeks gestation, offer varicella zoster immunoglobulin (VZIg).
This is held centrally by PHE, and can be ordered via the clinical virology team at UHCW for delivery to the GP surgery.
If the practice is unable to administer VZIg, the local Obstetrics team can usually arrange this but will need to ensure other pregnant women are not put at risk. VZIg can be given up to 10 days after initial exposure.
If contact was continuous e.g. household member, VZIg should be administered within 10 days of rash onset in the index case. The dose is 1g and comes as 4 x 250g vials, administered by im injection.
If >20 weeks gestation, offer prophylactic antivirals.
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.
If a 2nd exposure occurs 3 weeks after receiving VZIg and the patient remains IgG negative, a further dose is required.
Given the shorter half-life of antivirals, compared with VZIG, if there is a second exposure immediately after completion of the course, a 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