* severe or life threatening covid infection: severe disease is defined as: dyspnea, respiratory frequency ≥ 30/min, blood oxygen saturation ≤ 93%, partial pressure of arterial oxygen to fraction of inspired oxygen ratio \< 300, and/or lung infiltrates \> 50% within 24 to 48 hours. life threatening disease is defined as: respiratory failure, septic shock, and/or multiple organ dysfunction or failure . * pregnant or lactating females. * participation in any investigational clinical study, other than observational, within the past 30 days; or plans to participate in such a study at any time from the day of enrollment until 30 days post-treatment in the current study. * allergy or hypersensitivity to sirolimus. * taking immunosuppressive drugs. * glomerular filtration rate (gfr) \< 30 ml/min by ckd-epi equation. * liver cirrhosis . * decompensated heart failure. * known active tuberculosis (tb) or history of incompletely treated tb. * uncontrolled systemic bacterial or fungal infections. * drugs that may affect sirolimus level: antifungals, diltiazem, verapamil, nicardipine, phenytoin, phenobarbital, rifampicin, carbamazepine.

* severe or life threatening covid infection: severe disease is defined as: dyspnea, respiratory frequency ≥ 30/min, blood oxygen saturation ≤ 93%, partial pressure of arterial oxygen to fraction of inspired oxygen ratio \< 300, and/or lung infiltrates \> 50% within 24 to 48 hours. life threatening disease is defined as: respiratory failure, septic shock, and/or multiple organ dysfunction or failure . * pregnant or lactating females. * participation in any investigational clinical study, other than observational, within the past 30 days; or plans to participate in such a study at any time from the day of enrollment until 30 days post-treatment in the current study. * allergy or hypersensitivity to sirolimus. * taking immunosuppressive drugs. * glomerular filtration rate (gfr) \< 30 ml/min by ckd-epi equation. * liver cirrhosis . * decompensated heart failure. * known active tuberculosis (tb) or history of incompletely treated tb. * uncontrolled systemic bacterial or fungal infections. * drugs that may affect sirolimus level: antifungals, diltiazem, verapamil, nicardipine, phenytoin, phenobarbital, rifampicin, carbamazepine.

- severe or life threatening covid infection: severe disease is defined as: dyspnea, respiratory frequency ≥ 30/min, blood oxygen saturation ≤ 93%, partial pressure of arterial oxygen to fraction of inspired oxygen ratio < 300, and/or lung infiltrates > 50% within 24 to 48 hours. life threatening disease is defined as: respiratory failure, septic shock, and/or multiple organ dysfunction or failure . - pregnant or lactating females. - participation in any investigational clinical study, other than observational, within the past 30 days; or plans to participate in such a study at any time from the day of enrollment until 30 days post-treatment in the current study. - allergy or hypersensitivity to sirolimus. - taking immunosuppressive drugs. - glomerular filtration rate (gfr) < 30 ml/min by ckd-epi equation. - liver cirrhosis . - decompensated heart failure. - known active tuberculosis (tb) or history of incompletely treated tb. - uncontrolled systemic bacterial or fungal infections. - drugs that may affect sirolimus level: antifungals, diltiazem, verapamil, nicardipine, phenytoin, phenobarbital, rifampicin, carbamazepine.

- severe or life threatening covid infection: severe disease is defined as: dyspnea, respiratory frequency ≥ 30/min, blood oxygen saturation ≤ 93%, partial pressure of arterial oxygen to fraction of inspired oxygen ratio < 300, and/or lung infiltrates > 50% within 24 to 48 hours. life threatening disease is defined as: respiratory failure, septic shock, and/or multiple organ dysfunction or failure . - pregnant or lactating females. - participation in any investigational clinical study, other than observational, within the past 30 days; or plans to participate in such a study at any time from the day of enrollment until 30 days post-treatment in the current study. - allergy or hypersensitivity to sirolimus. - taking immunosuppressive drugs. - glomerular filtration rate (gfr) < 30 ml/min by ckd-epi equation. - liver cirrhosis . - decompensated heart failure. - known active tuberculosis (tb) or history of incompletely treated tb. - uncontrolled systemic bacterial or fungal infections. - drugs that may affect sirolimus level: antifungals, diltiazem, verapamil, nicardipine, phenytoin, phenobarbital, rifampicin, carbamazepine.