Intuitively, therefore, complement inhibitors may have a role in influencing outcomes in the pandemic, and nomacopan, a complement C5 and leukotriene B4 (LTB4) inhibitor previously used in the treatment of paroxysmal nocturnal haemoglobinuria (PNH) (11) and bullous pemphigoid (12), was trialled in a small group of COVID-19 patients (CORONET study, n = 7), classified as “severe” using the model developed in the CASCADE study. This evidence concerns the gene C5 and paroxysmal nocturnal hemoglobinuria.