Based on the results of KEGG enrichment analysis, we found that the mechanism of quercetin for COAD/COVID-19 is closely associated to apoptosis, oxidative stress, anti-inflammatory, anti-viral, immune, anti-cancer and related pathways including IL-17, TNF, and HIF-1, which is generally consistent with the results of GeneMANIA analysis. Here, TNF is linked to COVID-19.