COVID-19, complement, endothelial cells, expression, venous thromboembolism, infection, risk, coagulopathy, endothelial dysfunction, mortality, systemic lupus erythematosus, complement activation, complications, management, thrombocytopenia, antiphospholipid syndrome, heparin, plasminogen activator inhibitor-1, pathogenesis, antiphospholipid antibodies, cytokines, inhibition, thromboembolism, antibodies, anticoagulation, oxidative stress, plasma, respiratory distress syndrome, risk factors. This evidence concerns the gene SERPINE1 and venous thromboembolism.