Moreover, CD4+CD25+ T and CD8+CD25+ T cells (% and MFI) were increased in COVID-19 convalescent patients (Fig. 1D), while the frequency of CD4+CD62L+ T and CD8+CD62L+ T cells was decreased (Fig. 1E), suggesting that T cells in COVID-19 convalescent patients may be prone to activation. Here, CD4 is linked to COVID-19.