Compared to patients with non-COVID-19 respiratory infections, there was an expansion of central memory CD4+ T-cells and terminally differentiated CD8+ T-cells in COVID-19 patients at 1–3 months post-symptom onset that returned to levels observed in patients with other respiratory infections by 6–9 months post-symptom onset (Figure 4e,f). This evidence concerns the gene CD8A and respiratory tract infectious disorder.