PROS1 and COVID-19: For this reason, COVID-19 hospitalized patients often showed alterations of several coagulation parameters, such as activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, platelet count, fibrin degradation products (FDP), D-dimer, von Willebrand factor, factor VIII, factor V, factor II, tissue factor, antithrombin, thrombomodulin and protein S [19].