We propose the ITHACA trial (COVID-19 Treated by c1 esterase inHibitor And iCAtibant) to assess the efficacy and safety of the inhibitor of C1e/kallikrein and the inhibitor of bradykinin receptor 2 compared to standard care alone in the treatment of patients with pneumonia caused by COVID-19. Here, C1S is linked to susceptibility to pneumonia measurement.