Cutting Edge: Lung-Resident T Cells Elicited by SARS-CoV-2 Do Not Mediate Protection against Secondary Infection.

Immunity to pulmonary infection typically requires elicitation of lung-resident T cells that subsequently confer protection against secondary infection. The presence of tissue-resident T cells in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) convalescent patients is unknown. Using a sublethal mouse model of coronavirus disease 2019, we determined if SARS-CoV-2 infection potentiated Ag-specific pulmonary resident CD4+ and CD8+ T cell responses and if these cells mediated protection against secondary infection. S protein-specific T cells were present in resident and circulating populations. However, M and N protein-specific T cells were detected only in the resident T cell pool. Using an adoptive transfer strategy, we found that T cells from SARS-CoV-2 immune animals did not protect naive mice. These data indicate that resident T cells are elicited by SARS-CoV-2 infection but are not sufficient for protective immunity.