* patients with known history of serious allergic reactions, including anaphylaxis, to zilucoplan® or inability to receive antibiotic prophylaxis due to allergy to all of the antibiotics that can be given for prophylaxis of meningococcal disease * history of active or past meningococcal disease * invasive mechanical ventilation \> 24 h at randomization * patient on ecmo at screening * clinical frailty scale above 3 before onset of the covid-19 episode * weight below 54 kg as measured max 1 week prior to inclusion * weight above 150 kg as measured max 1 week prior to inclusion * active bacterial or fungal infection * unlikely to survive beyond 48h * neutrophil count below 1500 cells/microliter * platelets below 50.000/microliter * patients enrolled in another investigational drug study * patients on high dose systemic steroids (\> 8 mg methylprednisolone or equivalent for more than 1 month) or other moderately immunosuppressive drugs (in the opinion of the investigator) for covid19 unrelated disorder * patients on current complement inhibiting drugs * serum transaminase levels \>5 times upper limit of normal, unless there are clear signs of cytokine release syndrome defined by ldh \>300 iu/l and ferritin \>700 ng/ml * pregnant or breastfeeding females (all female subjects deemed of childbearing potential by the investigator must have negative pregnancy test at screening)

* patients with known history of serious allergic reactions, including anaphylaxis, to zilucoplan® or inability to receive antibiotic prophylaxis due to allergy to all of the antibiotics that can be given for prophylaxis of meningococcal disease * history of active or past meningococcal disease * invasive mechanical ventilation \> 24 h at randomization * patient on ecmo at screening * clinical frailty scale above 3 before onset of the covid-19 episode * weight below 54 kg as measured max 1 week prior to inclusion * weight above 150 kg as measured max 1 week prior to inclusion * active bacterial or fungal infection * unlikely to survive beyond 48h * neutrophil count below 1500 cells/microliter * platelets below 50.000/microliter * patients enrolled in another investigational drug study * patients on high dose systemic steroids (\> 8 mg methylprednisolone or equivalent for more than 1 month) or other moderately immunosuppressive drugs (in the opinion of the investigator) for covid19 unrelated disorder * patients on current complement inhibiting drugs * serum transaminase levels \>5 times upper limit of normal, unless there are clear signs of cytokine release syndrome defined by ldh \>300 iu/l and ferritin \>700 ng/ml * pregnant or breastfeeding females (all female subjects deemed of childbearing potential by the investigator must have negative pregnancy test at screening)

- patients with known history of serious allergic reactions, including anaphylaxis, to zilucoplan® or inability to receive antibiotic prophylaxis due to allergy to all of the antibiotics that can be given for prophylaxis of meningococcal disease - history of active or past meningococcal disease - invasive mechanical ventilation > 24 h at randomization - patient on ecmo at screening - clinical frailty scale above 3 before onset of the covid-19 episode - weight below 54 kg as measured max 1 week prior to inclusion - weight above 150 kg as measured max 1 week prior to inclusion - active bacterial or fungal infection - unlikely to survive beyond 48h - neutrophil count below 1500 cells/microliter - platelets below 50.000/microliter - patients enrolled in another investigational drug study - patients on high dose systemic steroids (> 8 mg methylprednisolone or equivalent for more than 1 month) or other moderately immunosuppressive drugs (in the opinion of the investigator) for covid19 unrelated disorder - patients on current complement inhibiting drugs - serum transaminase levels >5 times upper limit of normal, unless there are clear signs of cytokine release syndrome defined by ldh >300 iu/l and ferritin >700 ng/ml - pregnant or breastfeeding females (all female subjects deemed of childbearing potential by the investigator must have negative pregnancy test at screening)

- patients with known history of serious allergic reactions, including anaphylaxis, to zilucoplan® or inability to receive antibiotic prophylaxis due to allergy to all of the antibiotics that can be given for prophylaxis of meningococcal disease - history of active or past meningococcal disease - invasive mechanical ventilation > 24 h at randomization - patient on ecmo at screening - clinical frailty scale above 3 before onset of the covid-19 episode - weight below 54 kg as measured max 1 week prior to inclusion - weight above 150 kg as measured max 1 week prior to inclusion - active bacterial or fungal infection - unlikely to survive beyond 48h - neutrophil count below 1500 cells/microliter - platelets below 50.000/microliter - patients enrolled in another investigational drug study - patients on high dose systemic steroids (> 8 mg methylprednisolone or equivalent for more than 1 month) or other moderately immunosuppressive drugs (in the opinion of the investigator) for covid19 unrelated disorder - patients on current complement inhibiting drugs - serum transaminase levels >5 times upper limit of normal, unless there are clear signs of cytokine release syndrome defined by ldh >300 iu/l and ferritin >700 ng/ml - pregnant or breastfeeding females (all female subjects deemed of childbearing potential by the investigator must have negative pregnancy test at screening)

- patients with known history of serious allergic reactions, including anaphylaxis, to zilucoplan® or inability to receive antibiotic prophylaxis due to allergy to all of the antibiotics that can be given for prophylaxis of meningococcal disease - history of active or past meningococcal disease - invasive mechanical ventilation > 24 h at randomization - clinical frailty scale above 3 before onset of the covid-19 episode - weight below 54 kg as measured max 1 week prior to inclusion - weight above 150 kg as measured max 1 week prior to inclusion - active bacterial or fungal infection - unlikely to survive beyond 48h -neutrophil count below 1500 cells/microliter -platelets below 50.000/microliter - patients enrolled in another investigational drug study - patients on high dose systemic steroids (> 8 mg methylprednisolone or equivalent for more than 1 month) or other moderately immunosuppressive drugs (in the opinion of the investigator) for covid19 unrelated disorder -patients on current complement inhibiting drugs - serum transaminase levels >5 times upper limit of normal, unless there are clear signs of cytokine release syndrome defined by ldh >300 iu/l and ferritin >700 ng/ml - pregnant or breastfeeding females (all female subjects deemed of childbearing potential by the investigator must have negative pregnancy test at screening)

- patients with known history of serious allergic reactions, including anaphylaxis, to zilucoplan® or inability to receive antibiotic prophylaxis due to allergy to all of the antibiotics that can be given for prophylaxis of meningococcal disease - history of active or past meningococcal disease - invasive mechanical ventilation > 24 h at randomization - clinical frailty scale above 3 before onset of the covid-19 episode - weight below 54 kg as measured max 1 week prior to inclusion - weight above 150 kg as measured max 1 week prior to inclusion - active bacterial or fungal infection - unlikely to survive beyond 48h -neutrophil count below 1500 cells/microliter -platelets below 50.000/microliter - patients enrolled in another investigational drug study - patients on high dose systemic steroids (> 8 mg methylprednisolone or equivalent for more than 1 month) or other moderately immunosuppressive drugs (in the opinion of the investigator) for covid19 unrelated disorder -patients on current complement inhibiting drugs - serum transaminase levels >5 times upper limit of normal, unless there are clear signs of cytokine release syndrome defined by ldh >300 iu/l and ferritin >700 ng/ml - pregnant or breastfeeding females (all female subjects deemed of childbearing potential by the investigator must have negative pregnancy test at screening)