#71 Post-Exposure Prophylaxis for Varicella-Zoster Virus Exposure in High-Risk Children

Abstract

Abstract Background Despite universal childhood vaccination, Varicella-Zoster virus (VZV) remains a cause of severe infection following varicella exposure for immunocompromised children and high-risk infants. Post-exposure prophylaxis (PEP) is recommended to minimize this risk; however, providers may not consistently administer Varicella-specific immune globulin (VariZIG) as recommended in guidelines or may choose alternative regimens. The purpose of this study was to determine patterns of PEP for Varicella-Zoster Virus (VZV) at children’s hospitals. Method Using the Pediatric Health Information Systems database, clinical encounters with the ICD-9/10 codes for VZV exposure from 2009-2019 were reviewed. Only the first VZV exposure encounter for a given patient in the study period was included. Patients receiving prophylaxis or intravenous immunoglobulin (IVIG) within 30 days of the index encounter were also excluded. Presence of chronic illness or conditions at risk of progression to severe varicella disease was identified by reviewing ICD-9/10 codes for encounters in the prior 12 months. Choice and timing of PEP regimen exposure were identified, classified into the following categories: VZIG, intravenous immunoglobulin (IVIG), acyclovir, or combination prophylaxis. Clinical encounters for subsequent varicella disease within 30 days of exposure were recorded. Results There were 1770 children with first clinical encounters for VZV during the study period of which, 66 were excluded due to recent prior receipt of anti-viral therapy or IVIG. Of these 1704 children, 509 (29.9%) were prescribed PEP after VZV exposure, while 65 (3.8%) ultimately developed VZV disease. Of patients who received PEP, acyclovir was most frequently prescribed (n=195, 38.3%), divided between administration between1-4 days (n=132), 5-10 days (n=19), and both time periods (n=44), post-exposure. The proportion who received the other regimens was VariZIG (n=146, 28.7%), IVIG (n=115, 22.6%), and combination therapy (n=53, 10.4%). From 2009-2019, the proportion of children receiving acyclovir declined from 56% to 36%, VariZIG increased from 10 to 15%, IVIG decreased from 32 to 7%, while a similar percentage (8-9%) received a combination of Acyclovir and IG. The proportion of patients who subsequently had clinical encounters for varicella disease was highest for Acyclovir (30/195, 15.4%) followed by VariZIG (5/146, 3.4%), combination therapy (2/53, 3.8%), and IVIG alone (0/115). (p<0.0001). Of the 65 patients that developed VZV disease, 24/65 (36.9%) had at least one high-risk condition. Conclusion Varicella PEP in high-risk children was highly varied among children’s hospitals and often diverged from guideline recommendations. Use of acyclovir was associated with a higher rate of breakthrough infection. More consistent use of guideline-recommended agents like VariZIG may lead to less varicella disease and complications in high-risk children.