* 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 (with the exception of high-flow oxygen therapy). * 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

* 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 (with the exception of high-flow oxygen therapy). * 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

- 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 (with the exception of high-flow oxygen therapy). - 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

- 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 (with the exception of high-flow oxygen therapy). - 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

- 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

- 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

- 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

- 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