Proportion of patients with positive polyfunctional CMV-specific T-cell responses. The proportion of patients with positive polyfunctional CMV-specific CD4⁺ (A) and CD8⁺ (B) T-cell responses (defined by the phenotype IFN-γ plus ≥1 functional marker) at approximately day 90 after HCT in letermovir recipients and preemptive therapy recipients. Positive T-cell responses were further defined as those >.05% above background and at least threefold greater than the DMSO (negative control) response in the same cell subset.