1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) \> 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) \<20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 8. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 \[e.g., anakinra, canakinumab\], anti-il-6 \[e.g., tocilizumab, sarilumab, sitlukimab\]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 10. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 11. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). 12. received any live vaccine in the 4 weeks prior to screening. 13. known active tuberculosis. 14. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 15. history of pulmonary alveolar proteinosis (pap). 16. has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 17. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 18. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 19. previous participation in an activ-5/big effect trial (bet).

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) \> 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) \<20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 8. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 \[e.g., anakinra, canakinumab\], anti-il-6 \[e.g., tocilizumab, sarilumab, sitlukimab\]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 10. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 11. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). 12. received any live vaccine in the 4 weeks prior to screening. 13. known active tuberculosis. 14. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 15. history of pulmonary alveolar proteinosis (pap). 16. has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 17. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 18. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 19. previous participation in an activ-5/big effect trial (bet).

alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. subjects with a low glomerular filtration rate (egfr), specifically: subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. pregnancy or breast feeding. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. allergy to any study medication. received five or more doses of remdesivir prior to screening. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). received any live vaccine in the 4 weeks prior to screening. known active tuberculosis. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. history of pulmonary alveolar proteinosis (pap). has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. positive test for influenza virus during the current illness (influenza testing is not required by protocol). previous participation in an activ-5/big effect trial (bet).

alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. subjects with a low glomerular filtration rate (egfr), specifically: subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. pregnancy or breast feeding. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. allergy to any study medication. received five or more doses of remdesivir prior to screening. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). received any live vaccine in the 4 weeks prior to screening. known active tuberculosis. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. history of pulmonary alveolar proteinosis (pap). has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. positive test for influenza virus during the current illness (influenza testing is not required by protocol). previous participation in an activ-5/big effect trial (bet).

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 8. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 10. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 11. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). 12. received any live vaccine in the 4 weeks prior to screening. 13. known active tuberculosis. 14. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 15. history of pulmonary alveolar proteinosis (pap). 16. has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 17. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 18. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 19. previous participation in an activ-5/big effect trial (bet).

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 8. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 10. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 11. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). 12. received any live vaccine in the 4 weeks prior to screening. 13. known active tuberculosis. 14. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 15. history of pulmonary alveolar proteinosis (pap). 16. has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 17. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 18. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 19. previous participation in an activ-5/big effect trial (bet).

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received two or more doses of > 60 mg of prednisone or equivalent in the 7 days prior to screening. 8. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 10. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 11. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 12. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). 13. received any live vaccine in the 4 weeks prior to screening. 14. known active tuberculosis. 15. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 16. history of pulmonary alveolar proteinosis (pap). 17. has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 18. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 19. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 20. previous participation in an activ-5/big effect trial (bet).

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received two or more doses of > 60 mg of prednisone or equivalent in the 7 days prior to screening. 8. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 10. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 11. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 12. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of coronavirus disease 2019 (covid-19). 13. received any live vaccine in the 4 weeks prior to screening. 14. known active tuberculosis. 15. known history of human immunodeficiency virus (hiv), hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 16. history of pulmonary alveolar proteinosis (pap). 17. has a malignancy currently receiving immunosuppressive chemotherapy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 18. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 19. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 20. previous participation in an activ-5/big effect trial (bet).

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received two or more doses of > 60 mg of prednisone or equivalent in the 7 days prior to screening. 8. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 10. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 11. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 12. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of covid-19. 13. received any live vaccine in the 4 weeks prior to screening. 14. known active tuberculosis. 15. known history of hiv, hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 16. history of pulmonary alveolar proteinosis (pap). 17. has active malignancy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 18. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 19. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 20. previous participation in an activ-5/bet trial.

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with a low glomerular filtration rate (egfr), specifically: 1. subjects with a glomerular filtration rate (egfr) 20-30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of participation outweighs the potential risk of study participation. 2. all subjects with a glomerular filtration rate (egfr) <20 ml/min (including hemodialysis and hemofiltration) are excluded. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received five or more doses of remdesivir prior to screening. 7. received two or more doses of > 60 mg of prednisone or equivalent in the 7 days prior to screening. 8. received small molecule tyrosine kinase inhibitors, including janus kinase (jak) inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 10. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 11. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 12. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of covid-19. 13. received any live vaccine in the 4 weeks prior to screening. 14. known active tuberculosis. 15. known history of hiv, hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 16. history of pulmonary alveolar proteinosis (pap). 17. has active malignancy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 18. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results. 19. positive test for influenza virus during the current illness (influenza testing is not required by protocol). 20. previous participation in an activ-5/bet trial.

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with an estimated glomerular filtration rate (egfr) < 30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of receiving remdesivir outweighs the potential risk of study participation. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received three or more doses of remdesivir prior to study enrollment. 7. received two or more doses of > 60 mg of prednisone or equivalent in the 7 days prior to screening. 8. received small molecule tyrosine kinase inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 10. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 11. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 12. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of covid-19. 13. received any live vaccine in the 4 weeks prior to screening. 14. known active tuberculosis. 15. known history of hiv, hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 16. history of pulmonary alveolar proteinosis (pap). 17. has active malignancy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 18. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results.

1. alanine aminotransferase (alt) or aspartate aminotransferase (ast) > 5 times the upper limit of normal. 2. subjects with an estimated glomerular filtration rate (egfr) < 30 ml/min are excluded unless in the opinion of the principal investigator (pi), the potential benefit of receiving remdesivir outweighs the potential risk of study participation. 3. pregnancy or breast feeding. 4. anticipated discharge from the hospital or transfer to another hospital which is not a study site within 72 hours of enrollment. 5. allergy to any study medication. 6. received three or more doses of remdesivir prior to study enrollment. 7. received two or more doses of > 60 mg of prednisone or equivalent in the 7 days prior to screening. 8. received small molecule tyrosine kinase inhibitors (e.g., baricitinib, ibrutinib, acalabrutinib, imatinib, gefitinib), in the 4 weeks prior to screening. 9. received monoclonal antibodies targeting cytokines (e.g., tumor necrosis factor (tnf) inhibitors, anti-il-1 [e.g., anakinra, canakinumab], anti-il-6 [e.g., tocilizumab, sarilumab, sitlukimab]), or t-cells (e.g., abatacept) in the 4 weeks prior to screening. 10. received monoclonal antibodies targeting b-cells (e.g., rituximab, and including any targeting multiple cell lines including b-cells) in the 3 months prior to screening. 11. received granulocyte-macrophage colony-stimulating factor (gm-csf) agents (e.g., sargramostim) within 2 months prior to screening. 12. received other immunosuppressants in the 4 weeks prior to screening and in the judgement of the investigator, the risk of immunosuppression with lenzilumab is larger than the risk of covid-19. 13. received any live vaccine in the 4 weeks prior to screening. 14. known active tuberculosis. 15. known history of hiv, hepatitis b (hbv) or untreated hepatitis c (hcv) infection. 16. history of pulmonary alveolar proteinosis (pap). 17. has active malignancy, immunodeficiency, uncontrolled opportunistic infection, or uncontrolled cirrhosis. 18. has a medical condition that could, in the judgment of the investigator, limit the interpretation and generalizability of trial results.