Inclusion Criteria:  Men and women 25-80 years Individuals without active disease with previous confirmed diagnosis of COVID-19 infection with negative nasopharyngeal PCR test With characteristic chest radiographic images compatible with lung infection, particularly interstitial pneumonitis with previous unburied glass patches, cobblestone or areas of consolidation (during active disease) Sign a letter of consent under information  Exclusion Criteria:  Patients taking the following medicines: Ivermectin, azithromycin, corticosteroids, colchicine, chlorine dioxide, oral anticoagulants such as acenocoumarin, apixaban, rivaroxaban; bronchodilators such as β2-agonists such as salbutamol and derivatives, as well as inhaled anticholinergics of the ipratropium bromide type and derivatives. Patients who present medical difficulty or contraindication to perform the 6 km walk test in band Patients with a history of community-acquired pneumonia, pulmonary neoplasms, heart, renal, or hepatic failure