Given the evidence that pulmonary macrophages in severe COVID-19 express a range of genes associated with profibrotic functions including TGF-β and genes related to TGF-β signaling,12 it is reasonable to assume that macrophage-fibroblast intercellular communication might promote the pronounced expansion and activation of myofibroblasts and fibroblasts through TGF-β signaling. Here, TGFB1 is linked to COVID-19.