Cord blood transplant (CBT) recipients have a high incidence of herpes zoster (HZ) in the context of short-term peri-transplant antiviral prophylaxis. In 2009, international guidelines recommended HZ prophylaxis for at least 1 year after hematopoietic cell transplant (HCT). The impact of longer-term antiviral prophylaxis on HZ incidence after CBT is unknown.
We retrospectively analyzed varicella-zoster virus (VZV) seropositive CBT recipients who were transplanted between 2006-2016. We abstracted HZ events and other variables for up to 5 years post-CBT. We calculated the cumulative incidence of HZ and used Cox proportional hazards regression to identify variables associated with HZ.
The study cohort consisted of 227 patients. Among 1-year survivors, 91% were still receiving prophylaxis, for a median duration of 20.6 months. HZ occurred in 44 patients (19%) at a median of 23.6 months. The cumulative incidence of HZ by 1-year post-CBT was 1.8% (95% CI, 0.1%-4%) but increased to 26% (95% CI, 19%-33%) by 5 years. In a multivariable analysis, acute graft-versus-host disease was associated with increased risk, whereas antiviral prophylaxis was associated with reduced risk for HZ (adjusted hazard ratio, 0.19; 95% confidence interval, 0.09-0.4). There was no association between CD4+ T cell counts at 1-year post-CBT and subsequent risk for HZ.
We found a high incidence of HZ after CBT despite antiviral prophylaxis for >1 year. Based on these findings, we suggest longer duration of prophylaxis for HZ after CBT; prophylactic compliance, VZV-specific immune monitoring, and vaccination to mitigate HZ after CBT also require further study.

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