Typical features of activated endothelial cells are the exposure of adhesion molecules that in COVID-19 mediate endotheliitis, as well as the induction of pro-coagulation factors, such as von Willebrand factor and plasminogen activator inhibitor-1 (PAI-1), that play important roles in the abnormal coagulation associated with COVID-19. This evidence concerns the gene SERPINE1 and COVID-19.