* currently enrolled, planning to enroll, or participated, within the last 30 days, in a clinical study requiring administration of an investigational product (ie, not yet marketed), including expanded access or compassionate use * exceptions: * administration of investigational product with emergency use authorization granted for treatment of covid 19 (eg, remdesivir) is permitted * convalescent plasma as part of approved special access programs such as expanded access, emergency ind, or compassionate use is permitted * pregnant or breastfeeding (female subjects) * intubated and requires mechanical ventilation (including ecmo) at time of randomization * exception: use of hfnc oxygen and noninvasive ventilation are permitted * endotracheal intubation is imminent, in the opinion of the investigator * not expected to survive for more than 48 hours after hospital admission, in the opinion of the investigator * presence of any of the following comorbid conditions before randomization and prior to sars-cov-2 infection: * new york heart association class iv heart failure * stage 4 or 5 chronic kidney disease or requires renal replacement therapy * biopsy proven cirrhosis, portal hypertension or hepatic encephalopathy * stage iv malignancy * chronic lung disease requiring home oxygen * active tuberculosis * history or evidence of pulmonary alveolar proteinosis * confirmed diagnosis or clinical suspicion of bacterial pneumonia or active uncontrolled bacterial, fungal, or non sars-cov-2 viral infection at screening * absolute neutrophil count (anc) value \< 5 × 109 cells/l at screening (can be lowered up to \< 1.5 × 109 cells/l after independent data monitoring committee review of safety data, if csl324 induced neutropenia is not assessed as a safety concern) * currently receiving a prohibited therapy including g-csf, granulocyte-macrophage colony-stimulating factor (gm-csf), or antibody against interleukin 6 (il-6) / il 6 receptor (anti il-6 / 6r)

* currently enrolled, planning to enroll, or participated, within the last 30 days, in a clinical study requiring administration of an investigational product (ie, not yet marketed), including expanded access or compassionate use * exceptions: * administration of investigational product with emergency use authorization granted for treatment of covid 19 (eg, remdesivir) is permitted * convalescent plasma as part of approved special access programs such as expanded access, emergency ind, or compassionate use is permitted * pregnant or breastfeeding (female subjects) * intubated and requires mechanical ventilation (including ecmo) at time of randomization * exception: use of hfnc oxygen and noninvasive ventilation are permitted * endotracheal intubation is imminent, in the opinion of the investigator * not expected to survive for more than 48 hours after hospital admission, in the opinion of the investigator * presence of any of the following comorbid conditions before randomization and prior to sars-cov-2 infection: * new york heart association class iv heart failure * stage 4 or 5 chronic kidney disease or requires renal replacement therapy * biopsy proven cirrhosis, portal hypertension or hepatic encephalopathy * stage iv malignancy * chronic lung disease requiring home oxygen * active tuberculosis * history or evidence of pulmonary alveolar proteinosis * confirmed diagnosis or clinical suspicion of bacterial pneumonia or active uncontrolled bacterial, fungal, or non sars-cov-2 viral infection at screening * absolute neutrophil count (anc) value \< 5 × 109 cells/l at screening (can be lowered up to \< 1.5 × 109 cells/l after independent data monitoring committee review of safety data, if csl324 induced neutropenia is not assessed as a safety concern) * currently receiving a prohibited therapy including g-csf, granulocyte-macrophage colony-stimulating factor (gm-csf), or antibody against interleukin 6 (il-6) / il 6 receptor (anti il-6 / 6r)

- currently enrolled, planning to enroll, or participated, within the last 30 days, in a clinical study requiring administration of an investigational product (ie, not yet marketed), including expanded access or compassionate use - exceptions: - administration of investigational product with emergency use authorization granted for treatment of covid 19 (eg, remdesivir) is permitted - convalescent plasma as part of approved special access programs such as expanded access, emergency ind, or compassionate use is permitted - pregnant or breastfeeding (female subjects) - intubated and requires mechanical ventilation (including ecmo) at time of randomization - exception: use of hfnc oxygen and noninvasive ventilation are permitted - endotracheal intubation is imminent, in the opinion of the investigator - not expected to survive for more than 48 hours after hospital admission, in the opinion of the investigator - presence of any of the following comorbid conditions before randomization and prior to sars-cov-2 infection: - new york heart association class iv heart failure - stage 4 or 5 chronic kidney disease or requires renal replacement therapy - biopsy proven cirrhosis, portal hypertension or hepatic encephalopathy - stage iv malignancy - chronic lung disease requiring home oxygen - active tuberculosis - history or evidence of pulmonary alveolar proteinosis - confirmed diagnosis or clinical suspicion of bacterial pneumonia or active uncontrolled bacterial, fungal, or non sars-cov-2 viral infection at screening - absolute neutrophil count (anc) value < 5 × 109 cells/l at screening (can be lowered up to < 1.5 × 109 cells/l after independent data monitoring committee review of safety data, if csl324 induced neutropenia is not assessed as a safety concern) - currently receiving a prohibited therapy including g-csf, granulocyte-macrophage colony-stimulating factor (gm-csf), or antibody against interleukin 6 (il-6) / il 6 receptor (anti il-6 / 6r)

- currently enrolled, planning to enroll, or participated, within the last 30 days, in a clinical study requiring administration of an investigational product (ie, not yet marketed), including expanded access or compassionate use - exceptions: - administration of investigational product with emergency use authorization granted for treatment of covid 19 (eg, remdesivir) is permitted - convalescent plasma as part of approved special access programs such as expanded access, emergency ind, or compassionate use is permitted - pregnant or breastfeeding (female subjects) - intubated and requires mechanical ventilation (including ecmo) at time of randomization - exception: use of hfnc oxygen and noninvasive ventilation are permitted - endotracheal intubation is imminent, in the opinion of the investigator - not expected to survive for more than 48 hours after hospital admission, in the opinion of the investigator - presence of any of the following comorbid conditions before randomization and prior to sars-cov-2 infection: - new york heart association class iv heart failure - stage 4 or 5 chronic kidney disease or requires renal replacement therapy - biopsy proven cirrhosis, portal hypertension or hepatic encephalopathy - stage iv malignancy - chronic lung disease requiring home oxygen - active tuberculosis - history or evidence of pulmonary alveolar proteinosis - confirmed diagnosis or clinical suspicion of bacterial pneumonia or active uncontrolled bacterial, fungal, or non sars-cov-2 viral infection at screening - absolute neutrophil count (anc) value < 5 × 109 cells/l at screening (can be lowered up to < 1.5 × 109 cells/l after independent data monitoring committee review of safety data, if csl324 induced neutropenia is not assessed as a safety concern) - currently receiving a prohibited therapy including g-csf, granulocyte-macrophage colony-stimulating factor (gm-csf), or antibody against interleukin 6 (il-6) / il 6 receptor (anti il-6 / 6r)