anticipated need for icu care and/or ventilatory support (invasive or noninvasive) within 24 hours. evidence of acute cardiac injury, as determined by the investigator at the time of screening. this may be based upon clinical signs and symptoms, ecg findings, or elevated troponin i levels. evidence of acute kidney injury not due to pre-renal azotemia or urinary tract obstruction at the time of screening. oxygen saturation <90% on supplemental oxygen with a nasal cannula, including high-flow oxygen at the time of screening. requires non-invasive ventilation at the time of screening. requires dialysis at the time of screening. has received or is receiving anti-il-6 therapies (eg, tocilizumab, sarilumab, siltuximab, etc) for the treatment of covid-19; subjects receiving anti-il-6 therapies for underlying medical conditions unrelated to covid-19 are not excluded from eligibility. pregnant or lactating. history of photosensitivity or active skin disease that, in the opinion of the investigator, could be worsened by rbt-9. known hypersensitivity or previous anaphylaxis to rbt-9 (stannous protoporphyrin) or any tin-based product. treatment with an investigational drug or participation in an interventional trial within 30 days prior to the first dose of study drug. inability to comply with the requirements of the study protocol.

anticipated need for icu care and/or ventilatory support (invasive or noninvasive) within 24 hours. evidence of acute cardiac injury, as determined by the investigator at the time of screening. this may be based upon clinical signs and symptoms, ecg findings, or elevated troponin i levels. evidence of acute kidney injury not due to pre-renal azotemia or urinary tract obstruction at the time of screening. oxygen saturation <90% on supplemental oxygen with a nasal cannula, including high-flow oxygen at the time of screening. requires non-invasive ventilation at the time of screening. requires dialysis at the time of screening. has received or is receiving anti-il-6 therapies (eg, tocilizumab, sarilumab, siltuximab, etc) for the treatment of covid-19; subjects receiving anti-il-6 therapies for underlying medical conditions unrelated to covid-19 are not excluded from eligibility. pregnant or lactating. history of photosensitivity or active skin disease that, in the opinion of the investigator, could be worsened by rbt-9. known hypersensitivity or previous anaphylaxis to rbt-9 (stannous protoporphyrin) or any tin-based product. treatment with an investigational drug or participation in an interventional trial within 30 days prior to the first dose of study drug. inability to comply with the requirements of the study protocol.

1. anticipated need for icu care and/or ventilatory support (invasive or noninvasive) within 24 hours. 2. evidence of acute cardiac injury, as determined by the investigator at the time of screening. this may be based upon clinical signs and symptoms, ecg findings, or elevated troponin i levels. 3. evidence of acute kidney injury not due to pre-renal azotemia or urinary tract obstruction at the time of screening. 4. oxygen saturation <90% on supplemental oxygen with a nasal cannula, including high-flow oxygen at the time of screening. 5. requires non-invasive ventilation at the time of screening. 6. requires dialysis at the time of screening. 7. has received or is receiving anti-il-6 therapies (eg, tocilizumab, sarilumab, siltuximab, etc) for the treatment of covid-19; subjects receiving anti-il-6 therapies for underlying medical conditions unrelated to covid-19 are not excluded from eligibility. 8. pregnant or lactating. 9. history of photosensitivity or active skin disease that, in the opinion of the investigator, could be worsened by rbt-9. 10. known hypersensitivity or previous anaphylaxis to rbt-9 (stannous protoporphyrin) or any tin-based product. 11. treatment with an investigational drug or participation in an interventional trial within 30 days prior to the first dose of study drug. 12. inability to comply with the requirements of the study protocol.

1. anticipated need for icu care and/or ventilatory support (invasive or noninvasive) within 24 hours. 2. evidence of acute cardiac injury, as determined by the investigator at the time of screening. this may be based upon clinical signs and symptoms, ecg findings, or elevated troponin i levels. 3. evidence of acute kidney injury not due to pre-renal azotemia or urinary tract obstruction at the time of screening. 4. oxygen saturation <90% on supplemental oxygen with a nasal cannula, including high-flow oxygen at the time of screening. 5. requires non-invasive ventilation at the time of screening. 6. requires dialysis at the time of screening. 7. has received or is receiving anti-il-6 therapies (eg, tocilizumab, sarilumab, siltuximab, etc) for the treatment of covid-19; subjects receiving anti-il-6 therapies for underlying medical conditions unrelated to covid-19 are not excluded from eligibility. 8. pregnant or lactating. 9. history of photosensitivity or active skin disease that, in the opinion of the investigator, could be worsened by rbt-9. 10. known hypersensitivity or previous anaphylaxis to rbt-9 (stannous protoporphyrin) or any tin-based product. 11. treatment with an investigational drug or participation in an interventional trial within 30 days prior to the first dose of study drug. 12. inability to comply with the requirements of the study protocol.