varicella-zoster Post-exposure prophylaxis

• Among women who develop varicella infection during pregnancy, the risk of congenital varicella syndrome appears to be small (0.4 to 2 %)

Evaluating susceptibility

• A self-reported history of varicella among pregnant women is a powerful predictor of antibodies to varicella infection

Defining exposure

• Significant exposure to varicella infection, which is highly contagious, is defined as household contact, face to face contact with an index case for five minutes, or sharing the same hospital room with a contagious patient.
• Herpes zoster is much less contagious and usually requires close contact or exposure to open cutaneous lesions for transmission to occur

Immunoprophylaxis for the prevention of maternal varicella infection

• US Advisory Committee on Immunization Practices recommends VariZIG, a varicella zoster immune globulinpreparation, in all nonimmune pregnant women who have been exposed to persons with VZV
• Postexposure prophylaxis is not needed among women who were immunized with varicella vaccine in the past.

Choice of Product

1. VariZIG [varicella zoster immune globulin]

• should be administered as soon as possible within 10 days of exposure
• The efficacy of passive immunization after this time interval is not known
• The recommended dose is 125 units/10 kg body weight given IM, with a maximum dose of 625 units (5 vials).

2. Intravenous immunoglobulin

• For pregnant women who cannot receive VariZIG within 10 days of exposure, clinicians may choose either to administer a single dose of intravenous immunoglobulin (IVIG) at 400 mg/kg OR
• closely monitor for signs and symptoms of varicella and institute treatment with acyclovir if illness occurs

3. Antiviral therapy 

• There are no data on whether acyclovir is beneficial in reducing the risk of varicella after exposure during pregnancy

Pre-Exposure Prophylaxis

• Pregnant women should not receive this live vaccine because of the theoretical risk of inducing congenital disease.
• However, if a pregnant woman is found to be nonimmune during pregnancy, varicella vaccine should be recommended immediately after delivery with the second dose administered at the six-week postpartum visit.

Reference:

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