Post-Transplantation Cyclophosphamide Is Associated with an Increase in Non-Cytomegalovirus Herpesvirus Infections in Patients with Acute Leukemia and Myelodysplastic Syndrome

•The use of post-transplantation cyclophosphamide (PTCy) is associated with an increased risk of non-cytomegalovirus (CMV) herpesvirus infection.•This increase is driven primarily by a higher frequency of human herpesvirus 6 viremia in patients receiving PTCy.•Development of non-CMV herpesvirus infection is associated with increased nonrelapse mortality, especially in haploidentical transplantation recipients treated with PTCy.•Patients in PTCy cohorts who did not develop non-CMV herpesvirus infection had lower rates of chronic graft-versus-host disease.•Prospective trials should consider viral surveillance strategies in conjunction with immune reconstitution monitoring.