C4A and COVID-19: In the present cohort of COVID-19 patients, thrombomodulin, IL-6, FVIII, VWF:Ag, sEPCR, sC5b9, tPA, PAI-1 activity, C4, ICAM-1 and VCAM-1 plasma levels were higher than normal ranges, in line with previous studies that included patients with a severe disease [4,5,29].