question: Eculizumab, a terminal complement (C5)-inhibiting monoclonal antibody, was administered in five mechanically ventilated patients in life-threatening condition due to COVID-19-related acute respiratory distress syndrome (ARDS) between 23 March 2020 and 3 April 2020. Their clinical progress was monitored. The primary endpoint was mortality. One patient was excluded while two passed away. The remaining two patients survived. At the time of this study, the mortality rate in mechanically ventilated COVID-19 patients suffering from ARDS receiving the standard of care as their therapeutic regimen was reportedly as high as 97%. This pilot study demonstrates a 50% mortality rate in patients receiving eculizumab therapy.