This research is designed to determine if the adjuvanted recombinant glycoprotein E (gE)
herpes zoster (HZ) vaccine (Shingrix) has acceptable immunogenicity and safety in people who
have undergone allogeneic stem cell transplant (allo-SCT). Specifically, it will determine
the effect of the interval after transplantation on the immune response and if an additional
dose of vaccine is needed to improve the vaccine-induced responses.