Roy F Chemaly, MD, MPH, FIDSA, FACP, MD Anderson Cancer Center, Houston, TX, discusses the role of cell-mediated immunity monitoring for patients receiving hematopoietic stem cell transplantation (HSCT) who have cytomegalovirus (CMV) infection. CMV is one of the most common infections in patients who have received HSCT. Dr Chemaly outlines the development of an assay to test for cell-mediated immunity to CMV, in order to determine whether patients are susceptible to CMV infection post-transplant. Implementation of this assay in clinical practice could help to optimize the duration of prophylaxis therapy. This interview took place during the 47th Annual Meeting of the European Group for Blood and Marrow Transplantation (EBMT) 2021.