This is supported by unique associations between COVID-19 and high concentrations of growth factors implicated in IPF pathogenesis (EGF, PDGF-AB/BB, PDGF-AB/BB, FLT-3L, TGF-α), as well as close relationships between TGF-α, severe COVID-19, and related respiratory failure. This evidence concerns the gene FLT3LG and idiopathic pulmonary fibrosis.