* Diabetes mellitus, requiring at least 1 prescription medicine for management
* Documented chronic kidney disease with an estimated glomerular filtration rate \<30 mL/min, not on dialysis
* Obesity (Class 2 or 3; body mass index \>34.9 kg/m2)
* On immunosuppressive therapy
* Oxygen saturation between 90 and 95% with or without supplemental oxygen
4. Admitted to a hospital for observation and/or treatment (controlled facility may include an emergency room, urgent care facility, temporary/modular hospital, infusion center, clinical research unit, etc).
5. If female, must be postmenopausal, surgically sterile, or if of childbearing potential, must be practicing 2 effective methods of birth control during the study and through 30 days after completion of the study.
6. For females of childbearing potential, a urine pregnancy test must be negative at the Screening Visit.
7. If male, must be surgically sterile or willing to practice 2 effective methods of birth control during the study and through 30 days after completion of the study.
8. Must be willing and able to give informed consent and comply with all study procedures.
You may not be if
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.
Clareo Health | A Study to Evaluate the Effect of RBT-9 on Progression of COVID-19 in High-Risk Individuals (The PREVENT Study)
