Especially, we found that collagen proteins COL1A1, COL1A2, COL3A1), laminin proteins (LAMA2, LAMB1), inflammatory proteins (S100A8, S100A9), the matrix metalloproteinase MMP2, fibronectin FN1, and regulator ZEB1 were significantly upregulated in the fibroblasts of COVID-19 patients (Fig. 4E), which have been proved to be related to the increase of EMT-mediated fibrosis [22–24]. The gene discussed is S100A9; the disease is COVID-19.