Heparin is known to have anti-inflammatory effects both in the vasculature and in the airway, which could beneficially impact COVID-19-associated inflammation. Heparin binds to and modulates the activity of many proteins that mediate inflammation including IL-8, platelet growth factor 4 (PGF4), stromal-derived factor 1a, neutrophil elastase, P- and L-selectin, CD11b/CD18, major basic protein (MBP), and eosinophil cationic protein (ECP; 13, 47). The anti-inflammatory effects of heparin and its constituent heparan sulfate glycosaminoglycan fragments fall into two general mechanisms: 1) dampening of inflammation through interaction with proinflammatory proteins and 2) preventing adhesion and an influx of inflammatory cells to a diseased area.