underlying disease-related exclusion criteria 1. involvement in the trial is not in the patient's best interest according to the investigator's decision, including the presence of any condition that would, in the assessment of the investigator, not allow the protocol to be followed safely note: the investigator should particularly consider exclusion of patients at increased risk for serious or fatal aes in case of worsening of the pulmonary perfusion. this includes, but is not limited to, pre-existing pulmonary hypertension, severe chronic respiratory disease, severely increased risk for thromboembolic complications and moderate to severe left ventricular ejection fraction (lvef) dysfunction. in addition, other known risk factors of highest risk of mortality in covid-19 patients should be considered. 2. presence of respiratory failure, shock, and/or combined failure of other organs that requires icu monitoring in the near foreseeable future 3. critical patients whose expected survival time \<48-72 hours 4. presence of the following laboratory values at screening: * white blood cell count (wbc) \<1.0 x 109/l * platelet count \<100,000/mm³ (\<100 x 109/l) * total bilirubin\>2 x uln * alanine aminotransferase (alt) or gamma glutamyl transferase (ggt) \>5 x uln 5. participation in any other interventional clinical trial 6. hospitalization primarily for other reasons than covid-19 (including primarily for concomitant conditions during ongoing sars-cov-2 infection) 7. anticipated transport to a different hospital or institution, in particular when such transport is anticipated for pending ecmo or rrt treatment 8. clinical suspicion of a bacterial superinfection at screening imp-related exclusion criteria 9. patients who cannot take drugs orally 10. allergic or hypersensitive to the imp or any of the ingredients 11. use of the following concomitant medications is prohibited from screening to end of treatment with imp in this trial (up to day 14) if not indicated otherwise in this protocol: * concurrent use of any mycophenolate mofetil or of methotrexate exceeding 17.5 mg weekly * any medication known to significantly increase urinary elimination of uric acid, in particular lesinurad (zurampic™) as well as uricosuric drugs such as probenecid * current treatments for any malignancy, in particular irinotecan, paclitaxel, tretinoin, bosutinib, sorafenib, enasidenib, erlotinib, regorafenib, pazopanib and nilotinib * any drug significantly restricting water diuresis, in particular vasopressin and vasopressin analogs * use of rosuvastatin at daily doses higher than 10 mg * arbidol and colchicine * any use of other dhodh inhibitors, including teriflunomide (aubagio™) or leflunomide (arava™) * chloroquine and hydroxychloroquine during the entire trial unless taken for indicated use before entering the trial 12. use of any investigational product within 8 weeks or 5x the respective half-life before the date of informed consent, whichever is longer, and throughout the duration of the trial general exclusion criteria 13. patients who have a "do not intubate" or "do not resuscitate" order (unless the patient waives in writing this order and will allow intubation for the duration of the trial period) 14. patients with end-stage liver disease (child pugh c score) 15. history or presence of serious or acute heart disease such as uncontrolled cardiac dysrhythmia or arrhythmia, uncontrolled angina pectoris, cardiomyopathy, or uncontrolled congestive heart failure (new york heart association \[nyha\] class 3 or 4) note: nyha class 3: cardiac disease resulting in marked limitation of physical activity. patients are comfortable at rest. less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. nyha class 4: cardiac disease resulting in inability to carry on any physical activity without discomfort. symptoms of heart failure or the anginal syndrome may be present even at rest. if any physical activity is undertaken, discomfort is increased. 16. legal incapacity, limited legal capacity, or any other condition that makes the patient unable to provide consent for the trial 17. pregnant or breastfeeding 18. an employee of an investigator or sponsor or an immediate relative of an investigator or sponsor 19. patients institutionalized due to judicial order

underlying disease-related exclusion criteria 1. involvement in the trial is not in the patient's best interest according to the investigator's decision, including the presence of any condition that would, in the assessment of the investigator, not allow the protocol to be followed safely note: the investigator should particularly consider exclusion of patients at increased risk for serious or fatal aes in case of worsening of the pulmonary perfusion. this includes, but is not limited to, pre-existing pulmonary hypertension, severe chronic respiratory disease, severely increased risk for thromboembolic complications and moderate to severe left ventricular ejection fraction (lvef) dysfunction. in addition, other known risk factors of highest risk of mortality in covid-19 patients should be considered. 2. presence of respiratory failure, shock, and/or combined failure of other organs that requires icu monitoring in the near foreseeable future 3. critical patients whose expected survival time \<48-72 hours 4. presence of the following laboratory values at screening: * white blood cell count (wbc) \<1.0 x 109/l * platelet count \<100,000/mm³ (\<100 x 109/l) * total bilirubin\>2 x uln * alanine aminotransferase (alt) or gamma glutamyl transferase (ggt) \>5 x uln 5. participation in any other interventional clinical trial 6. hospitalization primarily for other reasons than covid-19 (including primarily for concomitant conditions during ongoing sars-cov-2 infection) 7. anticipated transport to a different hospital or institution, in particular when such transport is anticipated for pending ecmo or rrt treatment 8. clinical suspicion of a bacterial superinfection at screening imp-related exclusion criteria 9. patients who cannot take drugs orally 10. allergic or hypersensitive to the imp or any of the ingredients 11. use of the following concomitant medications is prohibited from screening to end of treatment with imp in this trial (up to day 14) if not indicated otherwise in this protocol: * concurrent use of any mycophenolate mofetil or of methotrexate exceeding 17.5 mg weekly * any medication known to significantly increase urinary elimination of uric acid, in particular lesinurad (zurampic™) as well as uricosuric drugs such as probenecid * current treatments for any malignancy, in particular irinotecan, paclitaxel, tretinoin, bosutinib, sorafenib, enasidenib, erlotinib, regorafenib, pazopanib and nilotinib * any drug significantly restricting water diuresis, in particular vasopressin and vasopressin analogs * use of rosuvastatin at daily doses higher than 10 mg * arbidol and colchicine * any use of other dhodh inhibitors, including teriflunomide (aubagio™) or leflunomide (arava™) * chloroquine and hydroxychloroquine during the entire trial unless taken for indicated use before entering the trial 12. use of any investigational product within 8 weeks or 5x the respective half-life before the date of informed consent, whichever is longer, and throughout the duration of the trial general exclusion criteria 13. patients who have a "do not intubate" or "do not resuscitate" order (unless the patient waives in writing this order and will allow intubation for the duration of the trial period) 14. patients with end-stage liver disease (child pugh c score) 15. history or presence of serious or acute heart disease such as uncontrolled cardiac dysrhythmia or arrhythmia, uncontrolled angina pectoris, cardiomyopathy, or uncontrolled congestive heart failure (new york heart association \[nyha\] class 3 or 4) note: nyha class 3: cardiac disease resulting in marked limitation of physical activity. patients are comfortable at rest. less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. nyha class 4: cardiac disease resulting in inability to carry on any physical activity without discomfort. symptoms of heart failure or the anginal syndrome may be present even at rest. if any physical activity is undertaken, discomfort is increased. 16. legal incapacity, limited legal capacity, or any other condition that makes the patient unable to provide consent for the trial 17. pregnant or breastfeeding 18. an employee of an investigator or sponsor or an immediate relative of an investigator or sponsor 19. patients institutionalized due to judicial order

underlying disease-related exclusion criteria involvement in the trial is not in the patient's best interest according to the investigator's decision, including the presence of any condition that would, in the assessment of the investigator, not allow the protocol to be followed safely note: the investigator should particularly consider exclusion of patients at increased risk for serious or fatal aes in case of worsening of the pulmonary perfusion. this includes, but is not limited to, pre-existing pulmonary hypertension, severe chronic respiratory disease, severely increased risk for thromboembolic complications and moderate to severe left ventricular ejection fraction (lvef) dysfunction. in addition, other known risk factors of highest risk of mortality in covid-19 patients should be considered. presence of respiratory failure, shock, and/or combined failure of other organs that requires icu monitoring in the near foreseeable future critical patients whose expected survival time <48-72 hours presence of the following laboratory values at screening: white blood cell count (wbc) <1.0 x 109/l platelet count <100,000/mm³ (<100 x 109/l) total bilirubin>2 x uln alanine aminotransferase (alt) or gamma glutamyl transferase (ggt) >5 x uln participation in any other interventional clinical trial hospitalization primarily for other reasons than covid-19 (including primarily for concomitant conditions during ongoing sars-cov-2 infection) anticipated transport to a different hospital or institution, in particular when such transport is anticipated for pending ecmo or rrt treatment clinical suspicion of a bacterial superinfection at screening imp-related exclusion criteria patients who cannot take drugs orally allergic or hypersensitive to the imp or any of the ingredients use of the following concomitant medications is prohibited from screening to end of treatment with imp in this trial (up to day 14) if not indicated otherwise in this protocol: concurrent use of any mycophenolate mofetil or of methotrexate exceeding 17.5 mg weekly any medication known to significantly increase urinary elimination of uric acid, in particular lesinurad (zurampic™) as well as uricosuric drugs such as probenecid current treatments for any malignancy, in particular irinotecan, paclitaxel, tretinoin, bosutinib, sorafenib, enasidenib, erlotinib, regorafenib, pazopanib and nilotinib any drug significantly restricting water diuresis, in particular vasopressin and vasopressin analogs use of rosuvastatin at daily doses higher than 10 mg arbidol and colchicine any use of other dhodh inhibitors, including teriflunomide (aubagio™) or leflunomide (arava™) chloroquine and hydroxychloroquine during the entire trial unless taken for indicated use before entering the trial use of any investigational product within 8 weeks or 5x the respective half-life before the date of informed consent, whichever is longer, and throughout the duration of the trial general exclusion criteria patients who have a "do not intubate" or "do not resuscitate" order (unless the patient waives in writing this order and will allow intubation for the duration of the trial period) patients with end-stage liver disease (child pugh c score) history or presence of serious or acute heart disease such as uncontrolled cardiac dysrhythmia or arrhythmia, uncontrolled angina pectoris, cardiomyopathy, or uncontrolled congestive heart failure (new york heart association [nyha] class 3 or 4) note: nyha class 3: cardiac disease resulting in marked limitation of physical activity. patients are comfortable at rest. less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. nyha class 4: cardiac disease resulting in inability to carry on any physical activity without discomfort. symptoms of heart failure or the anginal syndrome may be present even at rest. if any physical activity is undertaken, discomfort is increased. legal incapacity, limited legal capacity, or any other condition that makes the patient unable to provide consent for the trial pregnant or breastfeeding an employee of an investigator or sponsor or an immediate relative of an investigator or sponsor patients institutionalized due to judicial order

underlying disease-related exclusion criteria involvement in the trial is not in the patient's best interest according to the investigator's decision, including the presence of any condition that would, in the assessment of the investigator, not allow the protocol to be followed safely note: the investigator should particularly consider exclusion of patients at increased risk for serious or fatal aes in case of worsening of the pulmonary perfusion. this includes, but is not limited to, pre-existing pulmonary hypertension, severe chronic respiratory disease, severely increased risk for thromboembolic complications and moderate to severe left ventricular ejection fraction (lvef) dysfunction. in addition, other known risk factors of highest risk of mortality in covid-19 patients should be considered. presence of respiratory failure, shock, and/or combined failure of other organs that requires icu monitoring in the near foreseeable future critical patients whose expected survival time <48-72 hours presence of the following laboratory values at screening: white blood cell count (wbc) <1.0 x 109/l platelet count <100,000/mm³ (<100 x 109/l) total bilirubin>2 x uln alanine aminotransferase (alt) or gamma glutamyl transferase (ggt) >5 x uln participation in any other interventional clinical trial hospitalization primarily for other reasons than covid-19 (including primarily for concomitant conditions during ongoing sars-cov-2 infection) anticipated transport to a different hospital or institution, in particular when such transport is anticipated for pending ecmo or rrt treatment clinical suspicion of a bacterial superinfection at screening imp-related exclusion criteria patients who cannot take drugs orally allergic or hypersensitive to the imp or any of the ingredients use of the following concomitant medications is prohibited from screening to end of treatment with imp in this trial (up to day 14) if not indicated otherwise in this protocol: concurrent use of any mycophenolate mofetil or of methotrexate exceeding 17.5 mg weekly any medication known to significantly increase urinary elimination of uric acid, in particular lesinurad (zurampic™) as well as uricosuric drugs such as probenecid current treatments for any malignancy, in particular irinotecan, paclitaxel, tretinoin, bosutinib, sorafenib, enasidenib, erlotinib, regorafenib, pazopanib and nilotinib any drug significantly restricting water diuresis, in particular vasopressin and vasopressin analogs use of rosuvastatin at daily doses higher than 10 mg arbidol and colchicine any use of other dhodh inhibitors, including teriflunomide (aubagio™) or leflunomide (arava™) chloroquine and hydroxychloroquine during the entire trial unless taken for indicated use before entering the trial use of any investigational product within 8 weeks or 5x the respective half-life before the date of informed consent, whichever is longer, and throughout the duration of the trial general exclusion criteria patients who have a "do not intubate" or "do not resuscitate" order (unless the patient waives in writing this order and will allow intubation for the duration of the trial period) patients with end-stage liver disease (child pugh c score) history or presence of serious or acute heart disease such as uncontrolled cardiac dysrhythmia or arrhythmia, uncontrolled angina pectoris, cardiomyopathy, or uncontrolled congestive heart failure (new york heart association [nyha] class 3 or 4) note: nyha class 3: cardiac disease resulting in marked limitation of physical activity. patients are comfortable at rest. less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. nyha class 4: cardiac disease resulting in inability to carry on any physical activity without discomfort. symptoms of heart failure or the anginal syndrome may be present even at rest. if any physical activity is undertaken, discomfort is increased. legal incapacity, limited legal capacity, or any other condition that makes the patient unable to provide consent for the trial pregnant or breastfeeding an employee of an investigator or sponsor or an immediate relative of an investigator or sponsor patients institutionalized due to judicial order

underlying disease-related exclusion criteria 1. involvement in the trial is not in the patient's best interest according to the investigator's decision, including the presence of any condition that would, in the assessment of the investigator, not allow the protocol to be followed safely note: the investigator should particularly consider exclusion of patients at increased risk for serious or fatal aes in case of worsening of the pulmonary perfusion. this includes, but is not limited to, pre-existing pulmonary hypertension, severe chronic respiratory disease, severely increased risk for thromboembolic complications and moderate to severe left ventricular ejection fraction (lvef) dysfunction. in addition, other known risk factors of highest risk of mortality in covid-19 patients should be considered. 2. presence of respiratory failure, shock, and/or combined failure of other organs that requires icu monitoring in the near foreseeable future 3. critical patients whose expected survival time <48-72 hours 4. presence of the following laboratory values at screening: - white blood cell count (wbc) <1.0 x 109/l - platelet count <100,000/mm³ (<100 x 109/l) - total bilirubin>2 x uln - alanine aminotransferase (alt) or gamma glutamyl transferase (ggt) >5 x uln 5. participation in any other interventional clinical trial 6. hospitalization primarily for other reasons than covid-19 (including primarily for concomitant conditions during ongoing sars-cov-2 infection) 7. anticipated transport to a different hospital or institution, in particular when such transport is anticipated for pending ecmo or rrt treatment 8. clinical suspicion of a bacterial superinfection at screening imp-related exclusion criteria 9. patients who cannot take drugs orally 10. allergic or hypersensitive to the imp or any of the ingredients 11. use of the following concomitant medications is prohibited from screening to end of treatment with imp in this trial (up to day 14) if not indicated otherwise in this protocol: - concurrent use of any mycophenolate mofetil or of methotrexate exceeding 17.5 mg weekly - any medication known to significantly increase urinary elimination of uric acid, in particular lesinurad (zurampic™) as well as uricosuric drugs such as probenecid - current treatments for any malignancy, in particular irinotecan, paclitaxel, tretinoin, bosutinib, sorafenib, enasidenib, erlotinib, regorafenib, pazopanib and nilotinib - any drug significantly restricting water diuresis, in particular vasopressin and vasopressin analogs - use of rosuvastatin at daily doses higher than 10 mg - arbidol and colchicine - any use of other dhodh inhibitors, including teriflunomide (aubagio™) or leflunomide (arava™) - chloroquine and hydroxychloroquine during the entire trial unless taken for indicated use before entering the trial 12. use of any investigational product within 8 weeks or 5x the respective half-life before the date of informed consent, whichever is longer, and throughout the duration of the trial general exclusion criteria 13. patients who have a "do not intubate" or "do not resuscitate" order (unless the patient waives in writing this order and will allow intubation for the duration of the trial period) 14. patients with end-stage liver disease (child pugh c score) 15. history or presence of serious or acute heart disease such as uncontrolled cardiac dysrhythmia or arrhythmia, uncontrolled angina pectoris, cardiomyopathy, or uncontrolled congestive heart failure (new york heart association [nyha] class 3 or 4) note: nyha class 3: cardiac disease resulting in marked limitation of physical activity. patients are comfortable at rest. less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. nyha class 4: cardiac disease resulting in inability to carry on any physical activity without discomfort. symptoms of heart failure or the anginal syndrome may be present even at rest. if any physical activity is undertaken, discomfort is increased. 16. legal incapacity, limited legal capacity, or any other condition that makes the patient unable to provide consent for the trial 17. pregnant or breastfeeding 18. an employee of an investigator or sponsor or an immediate relative of an investigator or sponsor 19. patients institutionalized due to judicial order

underlying disease-related exclusion criteria 1. involvement in the trial is not in the patient's best interest according to the investigator's decision, including the presence of any condition that would, in the assessment of the investigator, not allow the protocol to be followed safely note: the investigator should particularly consider exclusion of patients at increased risk for serious or fatal aes in case of worsening of the pulmonary perfusion. this includes, but is not limited to, pre-existing pulmonary hypertension, severe chronic respiratory disease, severely increased risk for thromboembolic complications and moderate to severe left ventricular ejection fraction (lvef) dysfunction. in addition, other known risk factors of highest risk of mortality in covid-19 patients should be considered. 2. presence of respiratory failure, shock, and/or combined failure of other organs that requires icu monitoring in the near foreseeable future 3. critical patients whose expected survival time <48-72 hours 4. presence of the following laboratory values at screening: - white blood cell count (wbc) <1.0 x 109/l - platelet count <100,000/mm³ (<100 x 109/l) - total bilirubin>2 x uln - alanine aminotransferase (alt) or gamma glutamyl transferase (ggt) >5 x uln 5. participation in any other interventional clinical trial 6. hospitalization primarily for other reasons than covid-19 (including primarily for concomitant conditions during ongoing sars-cov-2 infection) 7. anticipated transport to a different hospital or institution, in particular when such transport is anticipated for pending ecmo or rrt treatment 8. clinical suspicion of a bacterial superinfection at screening imp-related exclusion criteria 9. patients who cannot take drugs orally 10. allergic or hypersensitive to the imp or any of the ingredients 11. use of the following concomitant medications is prohibited from screening to end of treatment with imp in this trial (up to day 14) if not indicated otherwise in this protocol: - concurrent use of any mycophenolate mofetil or of methotrexate exceeding 17.5 mg weekly - any medication known to significantly increase urinary elimination of uric acid, in particular lesinurad (zurampic™) as well as uricosuric drugs such as probenecid - current treatments for any malignancy, in particular irinotecan, paclitaxel, tretinoin, bosutinib, sorafenib, enasidenib, erlotinib, regorafenib, pazopanib and nilotinib - any drug significantly restricting water diuresis, in particular vasopressin and vasopressin analogs - use of rosuvastatin at daily doses higher than 10 mg - arbidol and colchicine - any use of other dhodh inhibitors, including teriflunomide (aubagio™) or leflunomide (arava™) - chloroquine and hydroxychloroquine during the entire trial unless taken for indicated use before entering the trial 12. use of any investigational product within 8 weeks or 5x the respective half-life before the date of informed consent, whichever is longer, and throughout the duration of the trial general exclusion criteria 13. patients who have a "do not intubate" or "do not resuscitate" order (unless the patient waives in writing this order and will allow intubation for the duration of the trial period) 14. patients with end-stage liver disease (child pugh c score) 15. history or presence of serious or acute heart disease such as uncontrolled cardiac dysrhythmia or arrhythmia, uncontrolled angina pectoris, cardiomyopathy, or uncontrolled congestive heart failure (new york heart association [nyha] class 3 or 4) note: nyha class 3: cardiac disease resulting in marked limitation of physical activity. patients are comfortable at rest. less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. nyha class 4: cardiac disease resulting in inability to carry on any physical activity without discomfort. symptoms of heart failure or the anginal syndrome may be present even at rest. if any physical activity is undertaken, discomfort is increased. 16. legal incapacity, limited legal capacity, or any other condition that makes the patient unable to provide consent for the trial 17. pregnant or breastfeeding 18. an employee of an investigator or sponsor or an immediate relative of an investigator or sponsor 19. patients institutionalized due to judicial order