Retrospective and prospective evaluation of chickenpox post-exposure prophylaxis (PEP) in at-risk groups before and after the change in PEP guidelines

Abstract

Background Public Health England (PHE) chickenpox post-exposure prophylaxis (PEP) guidelines were updated in August 2018. Varicella Zoster Immunoglobulin (VZIg) was replaced with oral aciclovir or valaciclovir in specific settings. Method We retrospectively examined issues of VZIg between August 1 2017 and July 31 2018 at a transplantation centre that also had a large maternity service. In addition, since September 2018, information has been collected prospectively. Additional data were collected on exposure incident, patient risk group and any clinical or serological follow up. Results Thirty issues of VZIg were identified retrospectively over 12 months. These included 9 pregnant women and 21 immunosuppressed patients, average age was 7.6 years (median 4.4 years, SD 11.1). Prospective outcome data were collected since September 4 2018 involving 2 pregnant women and 6 immunosuppressed individuals. Clinical follow-up information was available for 2 pregnant women and 16 immunosuppressed patients. One pregnant woman exposed to her own child with chickenpox and 2 immunosuppressed patients developed clinical varicella at an average of 15.3 days post VZIg. Five immunosuppressed patients were VZV IgG negative post-exposure. Follow-up available to date for 2 of 8 exposure incidents after the change in guidance has shown no clinical or serological evidence of varicella infection. Discussion Where follow up information was available, 19 % developed attenuated VZV around 2 weeks after receiving VZIg. Given the new guidance on using aciclovir prophylaxis, prospective outcome data are being collected and no VZV infections have been noted to date.