C5AR1 and COVID-19: Notably, the C3 inhibitor AMY-101 has been used in four patients with COVID-19, who recovered (34, 35); the C5 activation inhibitor, eculizumab, as adjunctive treatment in 14 patients, 12 of whom recovered (35, 36); another anti-C5a antibody (BDB-001) was used in 2 patients with critical COVID-19, who recovered (37).