BACKGROUND Patients receiving immunosuppressive therapies might be more susceptible to COVID-19 . Conversely, an exaggerated inflammatory response to the SARS-CoV-2 infection might be blunted by certain forms of immunosuppression, which could be protective . Indeed, there are data from animal models demonstrating that complement may be a part of the pathophysiology of coronavirus infections . There is also evidence from an autopsy series demonstrating complement deposition in the lungs of patients with COVID-19 . This raises the question of whether patients on anti-complement therapy could be protected from COVID-19 . CASE REPORT Case 1 is a 39-year-old woman with an approximately 20-year history of paroxysmal nocturnal hemoglobinuria (PNH), who had recently been switched from treatment with eculizumab to ravulizumab prior to SARS-CoV-2 infection . Case 2 is a 54-year-old woman with a cadaveric renal transplant for lupus nephritis, complicated by thrombotic microangiopathy, who was maintained on eculizumab, which she started several months before she developed the SARS-CoV-2 infection . Case 3 is a 60-year-old woman with a 14-year history of PNH, who had been treated with eculizumab since 2012, and was diagnosed with COVID-19 at the time of her scheduled infusion . All 3 patients had a relatively mild course of COVID-19 .
CONCLUSIONS We see no evidence of increased susceptibility to SARS-CoV-2 in these patients on anti-complement therapy, which might actually have accounted for the mild course of infection . The effect of anti-complement therapy on COVID-19 disease needs to be determined in clinical trials.