PTGS2 and COVID-19: Otherwise, in a multicentre prospective study by MacCann et al. [16], 61 patients with COVID-19 were compared with 54 healthy controls, showing a greater downregulation of FCER1A (gene encodes for FcεRI on mast cells) in the moderate/severe COVID-19 group than the group with mild disease; a downregulation of the TNF-alpha, PTGS2, and IL1B genes in the moderate/severe COVID-19 group was also noted, suggesting the downregulation of mast cells’ activation.