1. Recent administration of hydroxychloroquine, chloroquine, or steroids 2. Recent administration of tocilizumab (IL-6 antibody) 3. Hospital acquired (HAP)-, Health Care acquired (HCAP)- or Ventilator associated-pneumonia (VAP) 4. Pneumonia exclusively of bacterial or fungal origin* bacterial pneumonia co-infected with viruses and/or other microorganisms may be entered into the study. Due to the short time window (up to 18 hours) between fulfillment of severity criteria (ie initiation of invasive mechanical ventilation or vasopressors administration, whichever comes first) and the start of the first dose of study treatment, patients with a pneumonia of suspected viral origin by any established standard diagnostic method routinely applied at the study site (eg oral swap antigen test, rt-PCR) can be entered into the study (confirmation of viral origin must be obtained afterwards) 5. Known or suspected Pneumocystis jirovecii (formerly known as Pneumocystis carinii) pneumonia 6. Aspiration pneumonia 7. Known active tuberculosis 8. A history of post-obstructive pneumonia 9. Cystic fibrosis 10. Any chronic lung disease requiring oxygen therapy at home 11. Presence of infection in another organ location caused by same pathogen (eg 12. Pneumococcal meningitis in the context of pneumococcal pneumonia) 13. Expected to have rapidly fatal disease within 72 hours after randomization 14. Inability to maintain a mean arterial pressure 50 mmHg prior to Screening despite the presence of vasopressors and intravenous fluids 15. Not expected to survive for 3 months due to other pre-existing medical conditions such as end-stage neoplasm or other diseases 16. A history of malignancy in the 5 years prior to screening, except for successfully surgically treated non-melanoma skin malignancies 17. Known primary immunodeficiency disorder or with HIV infection and acquired immune deficiency syndrome (AIDS) with CD4 count <200 cells/mm3 or not receiving highly active antiretroviral therapy (HAART) for HIV 18. Receiving immunosuppressant therapy (including chronic treatment with anti-TNFa) or on chronic high doses of steroids (single administration of 2 mg/kg body weight or 20 mg/day of prednisone or equivalent for 2 weeks) 19. Granulocyotopenia, not due to sepsis, as evidenced by leukocyte absolute neutrophil count <500 per µL>21 days prior to onset of pneumonia symptoms 20. Received stem cell therapy, or allogeneic transplantation (organ or bone marrow transplant) within the past 6 months 21. Receiving treatment with a biological agent (eg antibodies, cells), immunotherapy or plasma exchange treatment within the last 8 weeks 22. A known liver function impairment associated with liver cirrhosis (Child Pugh C) or known esophageal varices 23. Hospitalized within the previous 15 days 24. Conditions resulting in a New York Heart Association or Canadian Cardiovascular Society Class IV functional status 25. End-stage neuromuscular disorders (eg motor neuron diseases, myasthenia gravis, etc) or cerebral disorders that impair weaning 26. Patients with quadriplegi

1. Recent administration of hydroxychloroquine, chloroquine, or steroids 2. Recent administration of tocilizumab (IL-6 antibody) 3. Hospital acquired (HAP)-, Health Care acquired (HCAP)- or Ventilator associated-pneumonia (VAP) 4. Pneumonia exclusively of bacterial or fungal origin* bacterial pneumonia co-infected with viruses and/or other microorganisms may be entered into the study. Due to the short time window (up to 18 hours) between fulfillment of severity criteria (ie initiation of invasive mechanical ventilation or vasopressors administration, whichever comes first) and the start of the first dose of study treatment, patients with a pneumonia of suspected viral origin by any established standard diagnostic method routinely applied at the study site (eg oral swap antigen test, rt-PCR) can be entered into the study (confirmation of viral origin must be obtained afterwards) 5. Known or suspected Pneumocystis jirovecii (formerly known as Pneumocystis carinii) pneumonia 6. Aspiration pneumonia 7. Known active tuberculosis 8. A history of post-obstructive pneumonia 9. Cystic fibrosis 10. Any chronic lung disease requiring oxygen therapy at home 11. Presence of infection in another organ location caused by same pathogen (eg 12. Pneumococcal meningitis in the context of pneumococcal pneumonia) 13. Expected to have rapidly fatal disease within 72 hours after randomization 14. Inability to maintain a mean arterial pressure 50 mmHg prior to Screening despite the presence of vasopressors and intravenous fluids 15. Not expected to survive for 3 months due to other pre-existing medical conditions such as end-stage neoplasm or other diseases 16. A history of malignancy in the 5 years prior to screening, except for successfully surgically treated non-melanoma skin malignancies 17. Known primary immunodeficiency disorder or with HIV infection and acquired immune deficiency syndrome (AIDS) with CD4 count <200 cells/mm3 or not receiving highly active antiretroviral therapy (HAART) for HIV 18. Receiving immunosuppressant therapy (including chronic treatment with anti-TNFa) or on chronic high doses of steroids (single administration of 2 mg/kg body weight or 20 mg/day of prednisone or equivalent for 2 weeks) 19. Granulocyotopenia, not due to sepsis, as evidenced by leukocyte absolute neutrophil count <500 per µL>21 days prior to onset of pneumonia symptoms 20. Received stem cell therapy, or allogeneic transplantation (organ or bone marrow transplant) within the past 6 months 21. Receiving treatment with a biological agent (eg antibodies, cells), immunotherapy or plasma exchange treatment within the last 8 weeks 22. A known liver function impairment associated with liver cirrhosis (Child Pugh C) or known esophageal varices 23. Hospitalized within the previous 15 days 24. Conditions resulting in a New York Heart Association or Canadian Cardiovascular Society Class IV functional status 25. End-stage neuromuscular disorders (eg motor neuron diseases, myasthenia gravis, etc) or cerebral disorders that impair weaning 26. Patients with quadriplegi