CD8A and COVID-19: B44/N322-specific memory CD8+ T cells in COVID-19 convalescent individuals exhibit a high median frequency of approximately 3.6×10-5, and remain functional capacity of cytokine production (IFN-γ and TNF) and degranulation (CD107a) with a frequency of about 1×10-5 after 104 days post COVID-19 symptom onset, while the anti-S protein IgG titer fell below the detection limit after 79 days post symptom onset (16).