1. evidence of life-threatening dysrhythmia or cardiac arrest on presentation 2. intubated \>72 hours 3. absolute neutrophil count \< 1,000 per mm3 4. platelet count \< 50,000 per mm3 5. ast or alt \> 5x upper limit of normal 6. egfr \<30 ml/min/1.73m2 or requiring hemofiltration or dialysis 7. history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis 8. severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) 9. use of any immunomodulatory biologic, cell therapy, or small molecule jak inhibitor within past 7 days or 5 half lives or planned use of any of these agents unless approved by medical monitor 10. chronic (\>4 weeks) use of corticosteroids \>10mg/day of prednisone or equivalent 11. known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

1. evidence of life-threatening dysrhythmia or cardiac arrest on presentation 2. intubated \>72 hours 3. absolute neutrophil count \< 1,000 per mm3 4. platelet count \< 50,000 per mm3 5. ast or alt \> 5x upper limit of normal 6. egfr \<30 ml/min/1.73m2 or requiring hemofiltration or dialysis 7. history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis 8. severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) 9. use of any immunomodulatory biologic, cell therapy, or small molecule jak inhibitor within past 7 days or 5 half lives or planned use of any of these agents unless approved by medical monitor 10. chronic (\>4 weeks) use of corticosteroids \>10mg/day of prednisone or equivalent 11. known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

evidence of life-threatening dysrhythmia or cardiac arrest on presentation intubated >72 hours absolute neutrophil count < 1,000 per mm3 platelet count < 50,000 per mm3 ast or alt > 5x upper limit of normal egfr <30 ml/min/1.73m2 or requiring hemofiltration or dialysis history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) use of any immunomodulatory biologic, cell therapy, or small molecule jak inhibitor within past 7 days or 5 half lives or planned use of any of these agents unless approved by medical monitor chronic (>4 weeks) use of corticosteroids >10mg/day of prednisone or equivalent known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

evidence of life-threatening dysrhythmia or cardiac arrest on presentation intubated >72 hours absolute neutrophil count < 1,000 per mm3 platelet count < 50,000 per mm3 ast or alt > 5x upper limit of normal egfr <30 ml/min/1.73m2 or requiring hemofiltration or dialysis history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) use of any immunomodulatory biologic, cell therapy, or small molecule jak inhibitor within past 7 days or 5 half lives or planned use of any of these agents unless approved by medical monitor chronic (>4 weeks) use of corticosteroids >10mg/day of prednisone or equivalent known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

evidence of life-threatening dysrhythmia or cardiac arrest on presentation intubated >72 hours absolute neutrophil count < 1,000 per mm3 platelet count < 50,000 per mm3 ast or alt > 5x upper limit of normal egfr <30 ml/min/1.73m2 or requiring hemofiltration or dialysis history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

evidence of life-threatening dysrhythmia or cardiac arrest on presentation intubated >72 hours absolute neutrophil count < 1,000 per mm3 platelet count < 50,000 per mm3 ast or alt > 5x upper limit of normal egfr <30 ml/min/1.73m2 or requiring hemofiltration or dialysis history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

1. evidence of life-threatening dysrhythmia or cardiac arrest on presentation 2. intubated >72 hours 3. absolute neutrophil count < 1,000 per mm3 4. platelet count < 50,000 per mm3 5. ast or alt > 5x upper limit of normal 6. egfr <30 ml/min/1.73m2 or requiring hemofiltration or dialysis 7. history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis 8. severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) 9. known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.

1. evidence of life-threatening dysrhythmia or cardiac arrest on presentation 2. intubated >72 hours 3. absolute neutrophil count < 1,000 per mm3 4. platelet count < 50,000 per mm3 5. ast or alt > 5x upper limit of normal 6. egfr <30 ml/min/1.73m2 or requiring hemofiltration or dialysis 7. history of known anti-gm-csf autoantibodies or pulmonary alveolar proteinosis 8. severe chronic respiratory disease (e.g., copd, pah, ipf, ild) requiring supplemental oxygen therapy or mechanical ventilation pre-hospitalization (e.g., prior to covid-19 diagnosis) 9. known or suspected active and untreated tb, hiv, hepatitis b or c infection additional exclusion criteria are detailed in the protocol.