SARS-CoV-2-specific T cells exhibit phenotypic features reflecting helper function, lack of terminal differentiation, and high proliferation potential

Convalescing COVID-19 patients mount robust T cell responses against
SARS-CoV-2, suggesting an important role for 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 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 homeostatically proliferate, and can persist for over two 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 for
SARS-CoV-2-specific T cells in host control of COVID-19.