COL3A1 and idiopathic pulmonary fibrosis: As previously mentioned, some studies have reported that fibrosis in both IPF and COVID-19 can be, at least in part, driven by pFB (also called activated fibroblasts in some articles) characterized by the expression of a set of genes, such as CTHRC1, COL3A1, and COL1A. Among these genes, CTHRC1 has been proposed as one of the most specific (7).