VWF and COVID-19: However, a note of the studies have implicated pre-existing PVD in the severity of the COVID-19 infection or outcome, except for cerebrovascular disease (7) This leads us to hypothesize that COVID-19 may worsen pre-existing PVD and limb ischemia by directly targeting the endothelium or increasing blood viscosity and expression of coagulation factors such as von Willebrand Factor (vWF), fibrinogen, and d-dimers.