During the acute phase of COVID-19, A2/S269+CD8+ T cells were readily detected after ex vivo tetramer enrichment at a mean frequency of 1.44 × 10−5 (n = 3) in the CD8+ set, while the values for the A2/S269+CD8+ and A2/Orf1ab3183+CD8+ T cells from COVID-19 convalescents were 1.28 × 10−5 (n = 14) and 1.77 × 10−6 (n = 6), respectively (Fig. 3 A and D). Here, CD8A is linked to COVID-19.