CD8A and COVID-19: We observed that in addition to the spike protein (S, n = 4/6), CD8+ T cells against epitopes from other SARS-CoV-2 proteins (ORF1ab, n = 3/13; M, n = 2/4; and N, n = 1/2) were also present at a significantly higher frequency in patients with COVID-19 (mild/severe) when compared with unexposed individuals (Fig. 8, A to D).