SARS-CoV-2-Specific T Cells Exhibit Phenotypic Features of Helper Function, Lack of Terminal Differentiation, and High Proliferation Potential.

Convalescing coronavirus disease 2019 (COVID-19) patients mount robust T cell responses against SARS-CoV-2, suggesting an important role of T cells in viral clearance. To date, the phenotypes of SARS-CoV-2-specific T cells remain poorly defined. Using 38-parameter CyTOF, we phenotyped longitudinal specimens of SARS-CoV-2-specific CD4+ and CD8+ T cells from nine individuals who recovered from mild COVID-19. SARS-CoV-2-specific CD4+ T cells were exclusively Th1 cells and predominantly Tcm cells with phenotypic features of robust helper function. SARS-CoV-2-specific CD8+ T cells were predominantly Temra cells in a state of less terminal differentiation than most Temra cells. Subsets of SARS-CoV-2-specific T cells express CD127, can proliferate homeostatically, and can persist for over 2 months. Our results suggest that long-lived and robust T cell immunity is generated following natural SARS-CoV-2 infection and support an important role of SARS-CoV-2-specific T cells in host control of COVID-19.