Immunogenicity and Safety of a Live Herpes Zoster Vaccine in Hematopoietic Stem Cell Transplant Recipients

Abstract

BackgroundHerpes zoster (HZ) infection of hematopoietic stem cell transplant (HSCT) patients is of clinical concern. Vaccination could help restore immunity to varicella zoster virus (VZV); however, the immunogenicity and safety of live HZ vaccines in patients with hematologic malignancy is unclear. The aim of this study was to elucidate temporal immunogenicity of the HZ vaccine after HSCT and determine the safety and optimal timing of vaccination.MethodsLive HZ vaccine was administered to patients 2–5 years or >5 years post-HSCT. Control groups comprised healthy volunteers and patients with a hematologic malignancy who received cytotoxic chemotherapy. Humoral and cellular immunogenicity were measured using a glycoprotein enzyme-linked immunosorbent assay (gpELISA) and an interferon-γ (IFN-γ) enzyme-linked immunospot (ELISPOT) assay. Vaccine-related adverse events were also monitored.ResultsFifty-six patients with hematologic malignancy and 30 healthy volunteers were enrolled. The geometric mean fold rise (GMFR) in humoral immune responses of the 2–5 year and >5 year HSCT groups, and the healthy volunteer group, were comparable and significantly higher than that of the chemotherapy group (3.15, 95% CI [1.96-5.07] vs 5.05, 95% CI [2.50-10.20] vs 2.97, 95% CI [2.30-3.83] vs 1.42, 95% CI [1.08-1.86]). The GMFR of cellular immune responses was highest in the HSCT 2–5 year group and lowest in the chemotherapy group. No subject suffered clinically significant adverse events or reactivation of VZV within the follow-up period. ConclusionOur findings demonstrate that a live HZ vaccine is immunogenic and safe when administered 2 years post-HSCT.