CD8A and infection: Detected by direct in vitro TAME, the mean frequency of A2/S269-specific CD8+ T cells is approximately 1.65×10-6 in healthy pre-pandemic individuals (25), and 1.44×10-5 and 1.28×10-5 in the COVID-19 acute and convalescent patients, respectively (17), suggesting that A2/S269-specific CD8+ T cells exhibit a certain level of activation and expansion following natural infection, but significantly lower than N protein-derived N105+CD8+ T cell responses (25).