Safety of the Recombinant Herpes-Zoster Subunit Vaccine in Allogeneic Stem Cell Transplant Patients

Abstract

<h3>Introduction</h3> After allogeneic stem cell transplant (SCT), varicella zoster virus (VZV) necessitates long term chemoprophylaxis due to limitations of the live vaccine. The recombinant subunit vaccine containing VZV glycoprotein E with AS01_B adjuvant system (HZ/su, or Shingrix) has safety and efficacy data after autologous transplantation. However, data is absent in the setting of allogeneic SCT. Due to the highly immunogenic AS01b subunit component, concerns regarding stimulation of graft versus host disease (GVHD) reaction have prompted some institutions to avoid routine HZ/su vaccination early after SCT. <h3>Objectives</h3> The primary objective was to evaluate the total number of GVHD events following post-transplant vaccinations. <h3>Methods</h3> Single center retrospective chart review of SCT patients who received post-transplant vaccinations within their first year of transplant. Patients who received HZ/su + post-transplant vaccines between 2017 and 2018 were compared to a control arm who received only the post-transplant vaccines between 2015 and 2016. We collected data regarding timing of the vaccines, presence of IS therapy at time of vaccination, and changes in GVHD therapy after vaccination. We assessed GVHD events within 3 months after each vaccination. <h3>Results</h3> Forty-seven patients received HZ/su + post-transplant- vaccines compared to 49 control patients who received only the post-transplant vaccines. More patients in the control arm were on IS at time of vaccination. Being on IS was a risk factor for GVHD events, especially in the control group. Although there were more alternative donor transplant patients receiving HZ/su vaccine, there were no increase in events. <h3>Conclusion</h3> Overall, HZ/su vaccine does not seem to increase the incidence of GVHD events after vaccination. However, the presence of IS at the time of vaccination may be associated with an increased risk of GVHD events. Given the limitations of our study, prospective trials are needed to evaluate timing and risk factors to consider before HZ/su vaccination.