C5 and COVID-19: Some studies support that administration of the anti-C5 monoclonal antibody eculizumab and other anti-C5 drugs led to a rapid and marked decline in biomarkers, for systemic clotting and inflammation in critical COVID-19 patients, decreasing the cytokine cascade and ameliorating respiratory symptoms, as well as decreasing the events related to thrombosis and the eventual associated organ damage [39,40,41,42].