VWF and COVID-19: In fact, several studies reported that serious cases of SARS-CoV-2 infection present significantly increased D-dimer, longer prothrombin time, activated partial thromboplastin time, increased vWF activity and vWF antigen, as well as factor VIII, and plasminogen activator inhibitor 1 (PAI-1).11,17,26,29,30 Moreover, increased levels of thrombin-AT complexes have also been reported, thus suggesting that thrombin may be highly active in seriously ill COVID-19 patients.31