Sirolimus Treatment in Hospitalized Patients With COVID-19 Pneumonia

Inclusion Criteria: Subjects enrolled in the trial must meet all of the following criteria. * Confirmed COVID-19 pneumonia * Hypoxia as defined by room air oxygen saturation less than 92% or supplemental oxygen requirement * Presence of at least one additional biomarker that has been shown to predict poor prognosis: a) serum ferritin ≥500ug/l, b) LDH ≥250U/L, c) d-dimer ≥1ug/L, or d) lymphopenia as defined by absolute lymphocyte count \<1,000/uL * Age ≥ 18 years * Completed informed consent Exclusion Criteria: Subjects who meet ANY of the following criteria are not eligible for enrollment as study participants: * Known allergy or hypersensitivity to sirolimus * Inability or refusal to provide informed consent * Advanced respiratory support (high flow oxygen ≥ 15 L/min, CPAP, non-invasive or invasive mechanical ventilation) * Active enrollment in other interventional clinical drug trials. Co-enrollment in observational studies and biorepositories is allowed. * Pregnant women * Breast feeding * On chronic immunosuppression for other medical conditions such as rheumatological disorders, inflammatory bowel disease, or in patients with organ transplants. A list of these medications is provided in Section 12.3.4 * Any clinically significant medical disease which in the opinion of the investigator precludes the patient from enrolling in the trial, including (but not limited to): * History of liver cirrhosis * End stage renal disease or need for renal replacement therapy * Decompensated heart failure * Known active tuberculosis or history of incompletely treated tuberculosis * Uncontrolled systemic bacterial or fungal infections * Active viral infection other than COVID-19