inclusion criteria: - post-covid-19 interstitial lung disease (ild) patients who had completed the treatment of acute phase and have recovered, but despite after a month from recovery diagnosed as post-covid ild based upon the persistent respiratory symptoms with functional impairment and radiological sequela. - at least 30 days required after discharge for hospitalized patients and isolation termination for outpatients - confirmation of the diagnosis of covid-19 via real time polymerase chain reaction assay (rt-pcr) or antigen or antibody test in the acute phase of covid-19. - presence of sequelae interstitial changes in follow-up thorax high-resolution computed tomography (hrct)/ct. - presence of persistent respiratory symptoms in the post-covid-19 period or hypoxemia at rest and/or desaturation with exercise.

inclusion criteria: - post-covid-19 interstitial lung disease (ild) patients who had completed the treatment of acute phase and have recovered, but despite after a month from recovery diagnosed as post-covid ild based upon the persistent respiratory symptoms with functional impairment and radiological sequela. - at least 30 days required after discharge for hospitalized patients and isolation termination for outpatients - confirmation of the diagnosis of covid-19 via real time polymerase chain reaction assay (rt-pcr) or antigen or antibody test in the acute phase of covid-19. - presence of sequelae interstitial changes in follow-up thorax high-resolution computed tomography (hrct)/ct. - presence of persistent respiratory symptoms in the post-covid-19 period or hypoxemia at rest and/or desaturation with exercise.