PER1 and COVID-19: Some of the markers have expression changes in the same direction in COVID-19 and AD or AD-related pathologies, including TGFB1, GSTM3, and NKTR. Using the PBMC single-cell RNA-sequencing data, we found that prostaglandin-endoperoxide synthase 2 (PTGS2) and period circadian regulator 1 (PER1) were significantly elevated in monocytes (Fig. S3) of severe COVID-19 patients.