VWF and COVID-19: This reduction may be related to increased pro-coagulant factors (such as factor VIII, vWF, and fibrinogen) and endothelial damage caused by cytokines induced by COVID-19.[5] The decrease in ADAMTS-13 activity levels is associated with the severity and prognosis of the viral infection and may increase mortality.[6] ADAMTS-13 changes are more complex in SLE complicated by TTP.