The expression of Prostaglandin-endoperoxide synthase 2 (PTGS2, also known as cyclooxygenase 2) mRNA was increased in PBMC of mild, but not severe COVID-19 patients, whereas the expression of NADPH oxidase (NOX-1) mRNA was reduced in both mild and severe COVID-19 patients compared to healthy donors. This evidence concerns the gene PTGS2 and COVID-19.