In the case of the COVID-19, there are several rationales which suggest that melatonin may reduce the COVID-19 -associated complications, as melatonin has been suggested to block the nuclear translocation of NF-κB, the expression of c-Fos, and suppression of matrix metalloproteinases-3 (MMP-3), which are responsible for pro-fibrotic and pro-inflammatory cytokine production [188,189]. This evidence concerns the gene FOS and COVID-19.