inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening 4. able to perform a pft and have a dlco \<70% of predicted at screening 5. able to perform a 6-minute walk test 6. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh \< 2x uln and bilirubin \< 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10\^9 / l and platelets ≥ 100x10\^9 / l 7. female patients of childbearing potential must have a negative pregnancy test at screening 8. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 9. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening 4. able to perform a pft and have a dlco \<70% of predicted at screening 5. able to perform a 6-minute walk test 6. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh \< 2x uln and bilirubin \< 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10\^9 / l and platelets ≥ 100x10\^9 / l 7. female patients of childbearing potential must have a negative pregnancy test at screening 8. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 9. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: age ≥ 18 patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening able to perform a pft and have a dlco <70% of predicted at screening able to perform a 6-minute walk test blood routine, liver and kidney function test values are within the controllable range adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l female patients of childbearing potential must have a negative pregnancy test at screening female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: age ≥ 18 patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening able to perform a pft and have a dlco <70% of predicted at screening able to perform a 6-minute walk test blood routine, liver and kidney function test values are within the controllable range adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l female patients of childbearing potential must have a negative pregnancy test at screening female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: age ≥ 18 patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) patients who met the criteria for covid-19-related acute respiratory distress syndrome (ards) while hospitalized as defined by the following: acute onset (within 14 days of initial symptoms); and at least one of: invasive or non-invasive mechanical ventilation with a pao2/fio2 (or correlated sao2/fio2) < 300 mmhg with peep > 5 cm h2o, or high flow nasal oxygen (>70% o2) administered for ≥ 48 hours; and bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules; and respiratory failure not fully explained by cardiac failure or fluid overload. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening able to perform a pft and have a dlco <70% of predicted at screening able to perform a 6-minute walk test blood routine, liver and kidney function test values are within the controllable range adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l female patients of childbearing potential must have a negative pregnancy test at screening female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: age ≥ 18 patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) patients who met the criteria for covid-19-related acute respiratory distress syndrome (ards) while hospitalized as defined by the following: acute onset (within 14 days of initial symptoms); and at least one of: invasive or non-invasive mechanical ventilation with a pao2/fio2 (or correlated sao2/fio2) < 300 mmhg with peep > 5 cm h2o, or high flow nasal oxygen (>70% o2) administered for ≥ 48 hours; and bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules; and respiratory failure not fully explained by cardiac failure or fluid overload. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening able to perform a pft and have a dlco <70% of predicted at screening able to perform a 6-minute walk test blood routine, liver and kidney function test values are within the controllable range adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l female patients of childbearing potential must have a negative pregnancy test at screening female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. patients who met the criteria for covid-19-related acute respiratory distress syndrome (ards) while hospitalized as defined by the following: 1. acute onset (within 14 days of initial symptoms); and 2. at least one of: invasive or non-invasive mechanical ventilation with a pao2/fio2 (or correlated sao2/fio2) < 300 mmhg with peep > 5 cm h2o, or high flow nasal oxygen (>70% o2) administered for ≥ 48 hours; and 3. bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules; and 4. respiratory failure not fully explained by cardiac failure or fluid overload. 4. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening 5. able to perform a pft and have a dlco <70% of predicted at screening 6. able to perform a 6-minute walk test 7. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 8. female patients of childbearing potential must have a negative pregnancy test at screening 9. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 10. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 365 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. patients who met the criteria for covid-19-related acute respiratory distress syndrome (ards) while hospitalized as defined by the following: 1. acute onset (within 14 days of initial symptoms); and 2. at least one of: invasive or non-invasive mechanical ventilation with a pao2/fio2 (or correlated sao2/fio2) < 300 mmhg with peep > 5 cm h2o, or high flow nasal oxygen (>70% o2) administered for ≥ 48 hours; and 3. bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules; and 4. respiratory failure not fully explained by cardiac failure or fluid overload. 4. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows at screening 5. able to perform a pft and have a dlco <70% of predicted at screening 6. able to perform a 6-minute walk test 7. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 8. female patients of childbearing potential must have a negative pregnancy test at screening 9. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum of 5 days prior to the first scheduled day of study intervention dosing are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 10. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 56 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. patients who had a clinical diagnosis of covid-19-related acute respiratory distress syndrome (ards) when hospitalized 4. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows 5. able to perform a pft and have a dlco <60% of predicted at discharge 6. able to perform a 6-minute walk test 7. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 8. female patients of childbearing potential must have a negative pregnancy test on day 1 (screening visit) of protocol 9. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum 5 days are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 10. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 56 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. patients who had a clinical diagnosis of covid-19-related acute respiratory distress syndrome (ards) when hospitalized 4. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows 5. able to perform a pft and have a dlco <60% of predicted at discharge 6. able to perform a 6-minute walk test 7. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 8. female patients of childbearing potential must have a negative pregnancy test on day 1 (screening visit) of protocol 9. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum 5 days are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 10. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 28 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. patients who had a clinical diagnosis of covid-19-related acute respiratory distress syndrome (ards) when hospitalized 4. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows 5. able to perform a pft and have a dlco <60% of predicted at discharge 6. able to perform a 6-minute walk test 7. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 8. female patients of childbearing potential must have a negative pregnancy test on day 1 (screening visit) of protocol 9. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum 5 days are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 10. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 28 days of discharge (even if the patient was referred to subacute or acute respiratory rehabilitation after discharge) 3. patients who had a clinical diagnosis of covid-19-related acute respiratory distress syndrome (ards) when hospitalized 4. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows 5. able to perform a pft and have a dlco <60% of predicted at discharge 6. able to perform a 6-minute walk test 7. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alt, ast and ldh < 2x uln and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 8. female patients of childbearing potential must have a negative pregnancy test on day 1 (screening visit) of protocol 9. female patients of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-estrogen-based contraception (e.g., condom and a diaphragm, condom and intrauterine device, condom and depo-provera, condom and nexplanon, or condom and progesterone mini-pill) during the 12-week portion of the study that they are receiving study medication and for 30 days following the last dose of study medication, or to abstain from sexual intercourse during these time periods. women who have been off estrogen contraceptives for a minimum 5 days are eligible. a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 10. ability of the patient or the patient's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 28 days of discharge 3. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows 4. participants are able to perform a pulmonary function test (pft) and have a dlco <60% of predicted at discharge 5. participants are able to perform a 6-minute walk test 6. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alanine aminotransferase (alt), aspartate aminotransferase (ast) or lactate dehydrogenase (ldh) < 2x upper limit of normal (uln) and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 7. female participants of childbearing potential must have a negative pregnancy test on day 1 (screening visit) of protocol therapy 8. female participants of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-hormonal contraception (e.g., double-barrier methods such as a condom and a diaphragm, intrauterine device, copper intrauterine device (iud), etc.) during the study and for 30 days following the last dose of study medication or to abstain from sexual intercourse for this time; a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 9. ability of the participant or the participant's legal representative to read and provide written informed consent

inclusion criteria: 1. age ≥ 18 2. patients hospitalized for covid-19-related complications ready to be discharged and those within 28 days of discharge 3. radiographic signs of lung injury after standard treatment of covid-19 such as, ground glass opacity, consolidation, or fibrotic shadows 4. participants are able to perform a pulmonary function test (pft) and have a dlco <60% of predicted at discharge 5. participants are able to perform a 6-minute walk test 6. blood routine, liver and kidney function test values are within the controllable range 1. adequate hepatic function as evidenced by alanine aminotransferase (alt), aspartate aminotransferase (ast) or lactate dehydrogenase (ldh) < 2x upper limit of normal (uln) and bilirubin < 1.5x uln for the reference lab 2. adequate renal function as evidenced by a serum creatinine ≤ 1.5 x uln for the reference laboratory or a calculated creatinine clearance of ≥ 60 ml/min by the cockcroft-gault equation 3. adequate hematopoietic function as evidenced by white blood cells ≥ 3x10^9 / l and platelets ≥ 100x10^9 / l 7. female participants of childbearing potential must have a negative pregnancy test on day 1 (screening visit) of protocol therapy 8. female participants of childbearing potential and male participants with female sexual partners of childbearing potential must agree to use an effective method of non-hormonal contraception (e.g., double-barrier methods such as a condom and a diaphragm, intrauterine device, copper intrauterine device (iud), etc.) during the study and for 30 days following the last dose of study medication or to abstain from sexual intercourse for this time; a woman not of childbearing potential is one who has undergone bilateral oophorectomies or who is post-menopausal, defined as no menstrual periods for 12 consecutive months 9. ability of the participant or the participant's legal representative to read and provide written informed consent