inclusion criteria: * patients who were hospitalised with a pre-diagnosis of "severe covid-19 pneumonia" and thereafter diagnosis of covid-19 was also confirmed microbiologically with pcr positivity in respiratory tract samples were included into the study. they were randomized to the study and control group, respectively. patients with at least one of the criteria below were accepted as patients with severe covid-19 pneumonia; 1. presence of tachypnea ≥ 30/minute, spo2 level \< 90% in room air, pao2/fio2 \<300 in oxygen receiving patient 2. presence of specific radiological finding for covid-19 in lung tomography (bilateral lobular, peripherally located, diffuse patchy ground glass opacities) 3. mechanical ventilation requirement 4. acute organ dysfunction findings; patients with sofa (sepsis-related organ failure assessment) score \>2

inclusion criteria: * patients who were hospitalised with a pre-diagnosis of "severe covid-19 pneumonia" and thereafter diagnosis of covid-19 was also confirmed microbiologically with pcr positivity in respiratory tract samples were included into the study. they were randomized to the study and control group, respectively. patients with at least one of the criteria below were accepted as patients with severe covid-19 pneumonia; 1. presence of tachypnea ≥ 30/minute, spo2 level \< 90% in room air, pao2/fio2 \<300 in oxygen receiving patient 2. presence of specific radiological finding for covid-19 in lung tomography (bilateral lobular, peripherally located, diffuse patchy ground glass opacities) 3. mechanical ventilation requirement 4. acute organ dysfunction findings; patients with sofa (sepsis-related organ failure assessment) score \>2

inclusion criteria: patients who were hospitalised with a pre-diagnosis of "severe covid-19 pneumonia" and thereafter diagnosis of covid-19 was also confirmed microbiologically with pcr positivity in respiratory tract samples were included into the study. they were randomized to the study and control group, respectively. patients with at least one of the criteria below were accepted as patients with severe covid-19 pneumonia; presence of tachypnea ≥ 30/minute, spo2 level < 90% in room air, pao2/fio2 <300 in oxygen receiving patient presence of specific radiological finding for covid-19 in lung tomography (bilateral lobular, peripherally located, diffuse patchy ground glass opacities) mechanical ventilation requirement acute organ dysfunction findings; patients with sofa (sepsis-related organ failure assessment) score >2

inclusion criteria: patients who were hospitalised with a pre-diagnosis of "severe covid-19 pneumonia" and thereafter diagnosis of covid-19 was also confirmed microbiologically with pcr positivity in respiratory tract samples were included into the study. they were randomized to the study and control group, respectively. patients with at least one of the criteria below were accepted as patients with severe covid-19 pneumonia; presence of tachypnea ≥ 30/minute, spo2 level < 90% in room air, pao2/fio2 <300 in oxygen receiving patient presence of specific radiological finding for covid-19 in lung tomography (bilateral lobular, peripherally located, diffuse patchy ground glass opacities) mechanical ventilation requirement acute organ dysfunction findings; patients with sofa (sepsis-related organ failure assessment) score >2

inclusion criteria: - patients who were hospitalised with a pre-diagnosis of "severe covid-19 pneumonia" and thereafter diagnosis of covid-19 was also confirmed microbiologically with pcr positivity in respiratory tract samples were included into the study. they were randomized to the study and control group, respectively. patients with at least one of the criteria below were accepted as patients with severe covid-19 pneumonia; 1. presence of tachypnea ≥ 30/minute, spo2 level < 90% in room air, pao2/fio2 <300 in oxygen receiving patient 2. presence of specific radiological finding for covid-19 in lung tomography (bilateral lobular, peripherally located, diffuse patchy ground glass opacities) 3. mechanical ventilation requirement 4. acute organ dysfunction findings; patients with sofa (sepsis-related organ failure assessment) score >2

inclusion criteria: - patients who were hospitalised with a pre-diagnosis of "severe covid-19 pneumonia" and thereafter diagnosis of covid-19 was also confirmed microbiologically with pcr positivity in respiratory tract samples were included into the study. they were randomized to the study and control group, respectively. patients with at least one of the criteria below were accepted as patients with severe covid-19 pneumonia; 1. presence of tachypnea ≥ 30/minute, spo2 level < 90% in room air, pao2/fio2 <300 in oxygen receiving patient 2. presence of specific radiological finding for covid-19 in lung tomography (bilateral lobular, peripherally located, diffuse patchy ground glass opacities) 3. mechanical ventilation requirement 4. acute organ dysfunction findings; patients with sofa (sepsis-related organ failure assessment) score >2