Diao et al. showed that the surviving T cells in COVID-19 patients, particularly in those requiring ICU admission, appeared functionally exhausted [32]. Consistent with this report, here we found that both CD8+T cells and CD4+T cells had higher expression of PD-1 in influenza patients, particularly in the severe group during the acute phase of influenza infection. The gene discussed is CD4; the disease is COVID-19.