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

Background: Post-exposure prophylaxis (PEP) with varicella immunoglobulin is recommended to minimize risk of varicella complications for high-risk children. However, providers frequently use alternatives like acyclovir or intravenous immunoglobulin.

Methods: A retrospective cohort study was conducted of PEP for varicella in children from January 2009 to December 2019. Data were provided by 47 children's hospitals who participate in the Pediatric Health Information Systems database. Patients with clinical encounters for varicella exposure were reviewed. Choice of varicella PEP regimens, including differences by underlying condition and institution, and incidence of varicella disease were determined.

Results: A total of 1704 patients with first clinical encounters for varicella met inclusion criteria. Of these patients, 509 (29.9%) were prescribed PEP after varicella exposure, and 65 (3.8%) ultimately had a subsequent encounter for varicella disease. Of 509 patients who received PEP, acyclovir was most frequently prescribed (n = 195, 38.3%), followed by varicella immunoglobulin (n = 146, 28.7%), IVIG (n = 115, 22.6%), and combination therapy (n = 53, 10.4%). The highest proportion of varicella immunoglobulin use (10/20, 50%) was amongst children with diagnoses of rheumatological/gastrointestinal conditions. The highest proportion of acyclovir use (29/684, 4.2%) was amongst children with diagnoses of oncology/stem cell transplant conditions. The proportion of patients who subsequently had clinical encounters for varicella disease was highest for Acyclovir (30/195, 15.4%) followed by varicella immunoglobulin (5/146, 3.4%), combination therapy (2/53, 3.8%), and intravenous immunoglobulin alone (0/115) (P < .0001).

Conclusions: Varicella PEP in high-risk children was highly varied among children's hospitals. In our dataset, use of acyclovir was associated with a higher rate of subsequent encounters for Varicella disease.