Interestingly, a study analyzed the transcriptomes of CD4+ T cells of COVID-19 patients and found out CD25 was significantly upregulated in CD4+ T cells, but the proportion of FOXP3+ cells in CD4+ CD25+ T cells of severe patients is significantly reduced compared with moderate patients, the increasing expression of CD25 was correlated to the upregulation of FURIN which could promote the invasion of SARS-CoV-2 into lung epithelial cells (84). Here, CD4 is linked to COVID-19.