Safety of Live Attenuated High-Titer Varicella-Zoster Virus Vaccine in Pediatric Allogeneic Hematopoietic Stem Cell Transplantation Recipients

• Oka strain high-titer varicella-zoster virus vaccine was safely administered to 31 children after hematopoietic stem cell transplantation
• Seventeen of 31 were vaccinated within 24 months after hematopoietic stem cell transplantation without adverse effects
• After vaccination, 18 of 31 recipients (58.1%) were seropositive

Hematopoietic stem cell transplantation (HSCT) recipients have a high risk of varicella-zoster virus (VZV) infections. Although VZV vaccination may be beneficial in preventing VZV infections, data on safety and efficacy of VZV vaccines in HSCT recipients, particularly of zoster vaccine, are limited. We report our experience with the use of a single dose of an Oka strain high-titer zoster-equivalent varicella vaccine in pediatric allogeneic HSCT recipients. We administered the high-titer VZV vaccine to 31 pediatric allogeneic HSCT recipients without vaccine-type VZV infections. One patient developed varicella due to wild-type VZV 13 days after vaccination. No zoster developed after vaccination during a median follow-up period of 4.8 years from vaccination. No other adverse effects were observed. Eighteen of the 31 patients (58.1%) were seropositive after vaccination. Seventeen patients were vaccinated within 24 months after HSCT; the seropositivity of these patients did not significantly differ from that of patients vaccinated > 24 months after HSCT. VZV vaccination may be a safe and beneficial approach in preventing VZV infections after HSCT.