Suboptimal SARS-CoV-2−specific CD8 + T cell response associated with the prominent HLA-A*02:01 phenotype

Significance As the recall of CD8 + T cell memory promotes rapid recovery in, for example, influenza, we investigated circulating SARS-CoV-2−specific CD8 + T cells from COVID-19 patients. For two HLA-A*02:01 SARS-CoV-2−specific CD8 + T cell epitopes, we found that, while ex vivo frequencies of responding T cells were approximately fivefold higher than for pre−COVID-19 samples, they were ∼10-fold lower than for influenza or EBV-specific memory CD8 + T cells. Additionally, SARS-CoV-2−specific CD8 + T cells recovered from convalescent COVID-19 patients had an atypically high prevalence of stem cell memory, central memory, and naïve phenotypes. Might this unexpectedly low prevalence of classical effector memory T cells be a negative consequence of the infectious process that could be avoided by prior priming with an appropriately constituted vaccine?