Pathway enrichment analyses of the proteins that were significantly changed between HCs and COVID-19 patients revealed that the majority of altered proteins were involved in cytokine–cytokine receptor interaction and chemokine signaling, followed by intestinal network for immunoglobulin A production, IL-17 signaling pathway, and Toll-like receptor signaling pathway; to name the top five pathways (Fig. 1B). This evidence concerns the gene IL17A and COVID-19.