Examples include elevated protein expression with the severity of COVID-19 for proteins, including (1) Syndecan-1 (SYND1) [36,38,48], (2) S100 calcium-binding protein A12 (EN-RAGE or S100A12) [42,49,50], (3) Hepatocyte Growth Factor (HGF) [51,52,53] and (4) CUB domain-containing protein 1 (CDCP1) [54]. Here, SDC1 is linked to COVID-19.