Drug: Conestat alfa

Inclusion Criteria:

- Informed Consent as documented by signature

- admitted to the hospital because of confirmed (by a positive SARS-CoV-2 PCR result)
COVID-19 infection

- evidence of pulmonary involvement on CT scan or X-ray of the chest (e.g. ground glass
opacities)

- symptom onset within the previous 10 days, i.e. fever or one respiratory symptom
(patients presenting later may have already progressed to an inflammatory state that
is potentially not amenable to C1INH treatment) OR shortness of breath within the
previous 5 days

- expected to remain an inpatient over the next three calender days from time of
enrolment

- at least one additional risk factor for progression to mechanical ventilation: 1)
arterial hypertension, 2) >50 years, 3) obesity (BMI>30.0 kg/m2), 4) cardiovascular
disease, 5) chronic pulmonary disease, 7) chronic renal disease, 6) C-reactive protein
of >35mg/L, 7) oxygen saturation at rest in ambient air of <94%

Exclusion Criteria:

- Contraindications to the class of drugs under study (C1 esterase inhibitor), e.g.
known hypersensitivity or allergy to class of drugs or the investigational product

- Treatment with tocilizumab or another Il-6R or Il-6 inhibitor before enrolment

- History or suspicion of allergy to rabbits

- Women who are pregnant or breast feeding

- Active or planned treatment with any other complement inhibitor

- Liver cirrhosis (any Child-Pugh score)

- Incapacity or inability to provide informed consent

- Currently admitted to an ICU or expected admission within the next 24 hours

- Currently receiving invasive or non-invasive ventilation

- In the opinion of the treating time, death is deemed to be imminent and inevitable
within the next 24 hours

- Participation in another study with investigational drug within the 30 days preceding
and during the present study with the following exemptions: 1) participation in
COVID-19 drug trials started at least 48 hours before admission (e.g. postexposure
prophylaxis with hydroxychloroquine) and 2) participation in COVID-19 drug trials
during ICU admission

- Previous enrolment into the current study

- Enrolment of the investigator, his/her family members, employees and other dependent
persons

- Any uncontrolled or significant concurrent illness that would put the patient at a
greater risk or limit compliance with the study requirements