MMP1 and pulmonary fibrosis: It has been shown only recently that in post-COVID-19 pulmonary fibrosis, extensive lung scarring occurs when two aspects are present: not only an increase in the level of transforming growth factor β (TGF-β), interleukin-6 (IL-6), and expression of matrix metalloproteinase 1 and 7 (MMP-1, MMP-7) but also collagen deposition at the site of lung injury [49].