Post-Exposure Prophylaxis for Immunocompromised Children After VZV Exposure
Immunocompromised children require post-exposure prophylaxis with Varicella Zoster Immune Globulin (VariZIG) after exposure to varicella-zoster virus to prevent potentially fatal complications. 1
Risk Assessment for Immunocompromised Children
Immunocompromised individuals are at high risk for serious varicella infections, with severe disease occurring in approximately 30% of such persons with primary infection 1. The risk varies based on:
- Type of immunocompromise
- Degree of immunosuppression
- Type of exposure
- Prior immunity status
Post-Exposure Prophylaxis Options
1. Varicella Zoster Immune Globulin (VariZIG)
VariZIG is the first-line prophylaxis for exposed immunocompromised children without evidence of immunity:
- Must be administered within 96 hours of exposure for maximum effectiveness 1
- Indicated for immunocompromised patients including those with:
- Primary and acquired immune deficiency disorders
- Neoplastic diseases
- Those receiving immunosuppressive treatment 1
2. Acyclovir Prophylaxis
When VariZIG is unavailable or exposure was identified beyond the 96-hour window:
- Oral acyclovir can be used as alternative prophylaxis
- Dosing: 80 mg/kg/day divided into 4 doses (maximum 800 mg 4 times daily) for 7 days 2, 3
- Should be started 7-10 days after exposure 3
Special Considerations for Different Immunocompromised States
HIV-Infected Children
- HIV-infected children in CDC class 1 with CD4+ T-lymphocyte percentage ≥15% may receive varicella vaccine 1
- All other HIV-infected children should receive VariZIG after exposure 1
Children on Corticosteroids
- Children receiving high-dose systemic corticosteroids (≥2 mg/kg/day of prednisone or ≥20 mg/day for ≥14 days) require VariZIG after exposure 1, 4
- Children on inhaled, nasal, or topical steroids do not require special prophylaxis 1
Children with Malignancies
- Children with leukemia, lymphoma, or other malignancies should receive VariZIG after exposure 1
- Bone marrow transplant recipients should be considered non-immune regardless of previous history of varicella or vaccination 1, 5
Types of Exposure Requiring Prophylaxis
Prophylaxis is indicated after these types of exposure:
- Direct face-to-face contact with an infectious person indoors
- Significant contact duration (>5 minutes according to some experts, >1 hour according to others) 1
- Household exposure (highest risk - 65-100% transmission rate in susceptible contacts) 1
- Hospital room sharing with an infectious patient 1
Monitoring After Exposure
Even with prophylaxis, monitor exposed immunocompromised children for:
- Fever
- Development of rash
- Systemic symptoms
If varicella develops despite prophylaxis, prompt treatment with IV acyclovir is essential to prevent severe complications 6.
Pitfalls to Avoid
- Delayed recognition: Failure to identify exposure quickly can result in missing the 96-hour window for VariZIG administration
- Underestimating risk: Even localized herpes zoster can transmit VZV to susceptible contacts 1
- Relying on oral acyclovir alone: For severely immunocompromised patients, VariZIG is preferred when available 1, 6
- Assuming previous immunity: Bone marrow transplant recipients should be considered non-immune regardless of previous history 5
Early identification of exposure and prompt administration of appropriate prophylaxis are critical to prevent potentially fatal VZV infection in immunocompromised children.