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Varicella exposure in a neonatal intensive care unit: emergency management and control measures
1Department of Paediatrics, Prince of Wales Hospital, Chinese University of Hong Kong.
Insights
Rapid response to varicella zoster virus exposure in a NICU prevented chickenpox in 57 infants and 129 staff. Mass screening and targeted immunoglobulin were key, highlighting limitations in current infant immune status prediction.
Area of Science:
- Neonatal Intensive Care Unit (NICU) Management
- Infectious Disease Control
- Immunology
Background:
- Varicella zoster virus (VZV) exposure poses a significant risk in neonatal intensive-care units (NICUs).
- Effective VZV outbreak prevention requires accurate assessment of immune status in neonates and staff.
Purpose of the Study:
- To describe VZV exposure management in a NICU and evaluate prevention strategies.
- To assess the accuracy of American Academy of Pediatrics (AAP) guidelines for identifying susceptible preterm infants.
- To identify reliable methods for determining VZV immune status in neonates and staff.
Main Methods:
- Implemented emergency procedures including rapid VZV antibody testing (ELISA) for neonates and staff.
- Cohorted exposed infants based on immune status and administered VZV immunoglobulin (VZIG) to susceptible individuals.
- Evaluated risk factors (gestational age, postnatal age, birthweight, blood transfusions) for predicting VZV antibody status.
Main Results:
- No cases of chickenpox occurred among 57 exposed infants and 129 exposed staff members.
- AAP guidelines underestimated susceptibility in preterm infants; mass ELISA screening proved essential for accurate immune status determination.
- Postnatal age was the only independent predictor of VZV antibody status among evaluated risk factors.
Conclusions:
- A multi-faceted approach including rapid testing, cohorting, and VZIG administration effectively prevented VZV transmission in the NICU.
- Current AAP guidelines are insufficient for predicting immune status in preterm infants; universal screening is recommended.
- Prospective screening and vaccination of susceptible healthcare staff in high-risk units are crucial for preventing nosocomial VZV transmission.
Abstract:
We describe an exposure of varicella zoster virus in our neonatal intensive-care unit and the emergency procedures instituted to prevent an outbreak. Fifty-seven infants and 129 staff members were exposed but none developed chickenpox. The measures included rapid identification of varicella antibody status in all neonates and those staff members with uncertain history of varicella infection; cohorting of exposed infants according to immune status; and prompt administration of varicella zoster immunoglobulin to susceptible patients. The recommendation of the American Academy of Pediatrics did not accurately predict the immune status of preterm infants, as only one of the eight susceptible infants would have qualified for immunoglobulin prophylaxis if their guidelines had been followed. Mass screening of all exposed infants using the varicella zoster enzyme linked immunosorbent assay (ELISA) test was the only reliable means of determining the immune status. Of the four risk factors evaluated for the prediction of antibody status: gestational age, postnatal age, birthweight and episodes of blood transfusion, only postnatal age was found to independently predict the immune status of our patients. Because varicella zoster susceptible staff members are difficult to identify on the basis of history, we suggest that prospective screening of staff in high-risk units be undertaken and vaccination with live varicella vaccine be offered to susceptibles.