ICOS and influenza: A limitation of our work is the exclusion of CD161 and ICOS in our T-cell phenotyping panels, as recent reports identified populations of CD4+ CD161+ T-cells and ICOS+ CD38+ T-follicular helper cells that clonally expanded and persisted years after influenza vaccination in AML patients receiving chemotherapy and in healthy individuals receiving successive influenza vaccinations, respectively [50, 51].