inclusion criteria: 1. signed patient explanation sheet and informed consent for participation in the study. 2. men and women at the age from 18 through 75 years old. 3. fibrous changes in the lungs after covid-19 pneumonia: 1. covid-19 diagnosis in the past medical history confirmed by positive qualitative analysis of sars-cov-2 rna by pcr method; 2. the first symptoms of covid-19 appear no earlier than 2 months before the screening visit; 3. fibrous changes in the lungs characteristic for covid-19 confirmed by the chest ct scan at screening visit. 4. negative covid-19 screening test (confirmed). 5. severity grade 2 (moderate) or 3 (severe) according to the mmrc dyspnea scale at the screening and randomization visits. 6. decreased lung function fvc and/or dlco \<80% of the predicted value at the screening visit. 7. the patient's consent to use adequate contraception methods during the entire study and within 3 months after its completion. the adequate contraception methods include the use of the following: * oral or transdermal contraceptives; * condom or diaphragm (barrier method) with spermicide; * intrauterine device.

inclusion criteria: 1. signed patient explanation sheet and informed consent for participation in the study. 2. men and women at the age from 18 through 75 years old. 3. fibrous changes in the lungs after covid-19 pneumonia: 1. covid-19 diagnosis in the past medical history confirmed by positive qualitative analysis of sars-cov-2 rna by pcr method; 2. the first symptoms of covid-19 appear no earlier than 2 months before the screening visit; 3. fibrous changes in the lungs characteristic for covid-19 confirmed by the chest ct scan at screening visit. 4. negative covid-19 screening test (confirmed). 5. severity grade 2 (moderate) or 3 (severe) according to the mmrc dyspnea scale at the screening and randomization visits. 6. decreased lung function fvc and/or dlco \<80% of the predicted value at the screening visit. 7. the patient's consent to use adequate contraception methods during the entire study and within 3 months after its completion. the adequate contraception methods include the use of the following: * oral or transdermal contraceptives; * condom or diaphragm (barrier method) with spermicide; * intrauterine device.

inclusion criteria: signed patient explanation sheet and informed consent for participation in the study. men and women at the age from 18 through 75 years old. fibrous changes in the lungs after covid-19 pneumonia: covid-19 diagnosis in the past medical history confirmed by positive qualitative analysis of sars-cov-2 rna by pcr method; the first symptoms of covid-19 appear no earlier than 2 months before the screening visit; fibrous changes in the lungs characteristic for covid-19 confirmed by the chest ct scan at screening visit. negative covid-19 screening test (confirmed). severity grade 2 (moderate) or 3 (severe) according to the mmrc dyspnea scale at the screening and randomization visits. decreased lung function fvc and/or dlco <80% of the predicted value at the screening visit. the patient's consent to use adequate contraception methods during the entire study and within 3 months after its completion. the adequate contraception methods include the use of the following: oral or transdermal contraceptives; condom or diaphragm (barrier method) with spermicide; intrauterine device.

inclusion criteria: signed patient explanation sheet and informed consent for participation in the study. men and women at the age from 18 through 75 years old. fibrous changes in the lungs after covid-19 pneumonia: covid-19 diagnosis in the past medical history confirmed by positive qualitative analysis of sars-cov-2 rna by pcr method; the first symptoms of covid-19 appear no earlier than 2 months before the screening visit; fibrous changes in the lungs characteristic for covid-19 confirmed by the chest ct scan at screening visit. negative covid-19 screening test (confirmed). severity grade 2 (moderate) or 3 (severe) according to the mmrc dyspnea scale at the screening and randomization visits. decreased lung function fvc and/or dlco <80% of the predicted value at the screening visit. the patient's consent to use adequate contraception methods during the entire study and within 3 months after its completion. the adequate contraception methods include the use of the following: oral or transdermal contraceptives; condom or diaphragm (barrier method) with spermicide; intrauterine device.

inclusion criteria: 1. signed patient explanation sheet and informed consent for participation in the study. 2. men and women at the age from 18 through 75 years old. 3. fibrous changes in the lungs after covid-19 pneumonia: 1. covid-19 diagnosis in the past medical history confirmed by positive qualitative analysis of sars-cov-2 rna by pcr method; 2. the first symptoms of covid-19 appear no earlier than 2 months before the screening visit; 3. fibrous changes in the lungs characteristic for covid-19 confirmed by the chest ct scan at screening visit. 4. negative covid-19 screening test (confirmed). 5. severity grade 2 (moderate) or 3 (severe) according to the mmrc dyspnea scale at the screening and randomization visits. 6. decreased lung function fvc and/or dlco <80% of the predicted value at the screening visit. 7. the patient's consent to use adequate contraception methods during the entire study and within 3 months after its completion. the adequate contraception methods include the use of the following: - oral or transdermal contraceptives; - condom or diaphragm (barrier method) with spermicide; - intrauterine device.

inclusion criteria: 1. signed patient explanation sheet and informed consent for participation in the study. 2. men and women at the age from 18 through 75 years old. 3. fibrous changes in the lungs after covid-19 pneumonia: 1. covid-19 diagnosis in the past medical history confirmed by positive qualitative analysis of sars-cov-2 rna by pcr method; 2. the first symptoms of covid-19 appear no earlier than 2 months before the screening visit; 3. fibrous changes in the lungs characteristic for covid-19 confirmed by the chest ct scan at screening visit. 4. negative covid-19 screening test (confirmed). 5. severity grade 2 (moderate) or 3 (severe) according to the mmrc dyspnea scale at the screening and randomization visits. 6. decreased lung function fvc and/or dlco <80% of the predicted value at the screening visit. 7. the patient's consent to use adequate contraception methods during the entire study and within 3 months after its completion. the adequate contraception methods include the use of the following: - oral or transdermal contraceptives; - condom or diaphragm (barrier method) with spermicide; - intrauterine device.