VWF and deep vein thrombosis: Unlike macro-thrombosis in PE that is featured by excessive thrombin generation and aggravated by the imbalance between pro- and anti-coagulant factors, pulmonary micro-thrombosis is hallmarked by altered alveoli and pulmonary microvasculature associated with platelet/ultra-large von Willebrand factor multimers anchored to the injured endothelium and intra-alveolar fibrin deposition, which develops as a consequence of endotheliopathy due to direct viral infection and immune-mediated host response [37,38].