inclusion criteria: * ability to understand the study objectives and risks and provide signed and dated informed consent; * confirmed covid-19 infection (by pcr or antibody test); * pneumonia requiring hospitalization, and oxygen saturation of \<94% indoors or a need for auxiliary oxygen. the confirmed volume of lung damage by ct: not less than 30% and not more than 80%; * ability to proceed with inhalation by self;

inclusion criteria: * ability to understand the study objectives and risks and provide signed and dated informed consent; * confirmed covid-19 infection (by pcr or antibody test); * pneumonia requiring hospitalization, and oxygen saturation of \<94% indoors or a need for auxiliary oxygen. the confirmed volume of lung damage by ct: not less than 30% and not more than 80%; * ability to proceed with inhalation by self;

inclusion criteria: - ability to understand the study objectives and risks and provide signed and dated informed consent; - confirmed covid-19 infection (by pcr or antibody test); - pneumonia requiring hospitalization, and oxygen saturation of <94% indoors or a need for auxiliary oxygen. the confirmed volume of lung damage by ct: not less than 30% and not more than 80%; - ability to proceed with inhalation by self;

inclusion criteria: - ability to understand the study objectives and risks and provide signed and dated informed consent; - confirmed covid-19 infection (by pcr or antibody test); - pneumonia requiring hospitalization, and oxygen saturation of <94% indoors or a need for auxiliary oxygen. the confirmed volume of lung damage by ct: not less than 30% and not more than 80%; - ability to proceed with inhalation by self;