Cumulative incidence and kinetics of HHV-6B detection within 12 weeks after CAR T-cell infusion. (A) Heat map of HHV-6B reactivation kinetics after CARTx. Three participants with iciHHV-6 had HHV-6 detection at every tested time point and were excluded from this plot. Each row represents a patient, and each square represents a plasma sample. The intensity of color represents the viral load (negative samples are depicted in white). BCMA CARTx recipients are depicted at the bottom and CD19/CD20 CARTx recipients at the top of the heat map. (B) Cumulative incidence curve of HHV-6B reactivation within 12 weeks after CARTx: 6% (95% CI, 2.2-12.5). (C) Cumulative incidence of HHV-6B reactivation stratified by CAR T-cell target: BCMA, 6% (95% CI, 0.4-24.2) vs CD19/20, 6% (95% CI, 1.9-13.5). (D) Cumulative incidence of HHV-6B reactivation stratified by prior cytokine release syndrome (CRS) and/or ICANS, starting at week 2 after CAR T-cell infusion as a landmark analysis: prior CRS and/or ICANS, 7.9% (95% CI, 2.9-16.3) vs no prior CRS and/or ICANS, 0%. In all curves, death was treated as a competing risk. The Gray test was used for statistical comparisons.