PEPtalk 3: oral aciclovir is equivalent to varicella zoster immunoglobulin as postexposure prophylaxis against chickenpox in children with cancer - results of a multicentre UK evaluation.

Objective: To compare the occurrence of chickenpox in children with cancer who received varicella immunoglobulin (VZIG) or aciclovir as postexposure prophylaxis (PEP).
Design: Prospective multicentre service evaluation of children with cancer who received either VZIG or aciclovir as PEP following significant exposure to varicella zoster virus (VZV) over a 24-month period from May 2018.
Setting: Data were collected from 9 UK Paediatric Oncology Primary Treatment Centres.
Patients: Children under 16 years old with a diagnosis of cancer and/or previous haematopoietic stem cell transplant who were VZV seronegative at exposure and/or diagnosis and received PEP following significant VZV exposure.
Main Outcome Measures: The primary outcome was the incidence of breakthrough varicella within 6 weeks of VZV exposure and treatment with PEP.
Results: A total of 105 eligible patients were registered with a median age of 4.9 years (range 1.1-10.5 years). Underlying diagnoses were acute leukaemia (64), solid tumours (22), Langerhans cell histiocytosis (9), central nervous system (CNS) tumours (8) and other (2). Aciclovir was received by 86 patients (81.9%), 18 received VZIG (17.1%) and 1 valaciclovir (0.9%). There were seven reported break-through VZV infections in 103 patients at follow-up (7/103, 6.8%). Clinical VZV developed in 5/84 of the aciclovir group (6.0%, 95% CI 2.0 to 13.3) and 2/18 of VZIG group (11.1%, 95% CI 1.4 to 34.7). All breakthrough infections were either mild (5/7) or moderate (2/7) in severity.
Conclusion: Aciclovir is a safe and effective alternative to VZIG as VZV PEP in children with cancer and should be considered as standard of care.
Competing Interests: Competing interests: None declared.
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