The risk for the development of complications from COVID-19 occurs mainly in patients over 65 years of age, with obesity, arterial hypertension, chronic lung diseases and immunosuppression states. Since the persistence of radiological imaging correlates with physiological deterioration, these patients are likely to be at increased risk of parenchymal lung disease.

It is known that the administration of Ozone, in any of the three phases of COVID-19 infection, is useful in the management of acute disease, both for its viricidal and anti-inflammatory activity, however, in the convalescence stage when the persistence of sequelae that can severely affect the quality of life of patients is identified.

The objective of this study is to evaluate whether the administration by inhalation of ozone plasma favorably modifies lung function and inflammatory parameters in patients with pulmonary sequelae associated with coronavirus 19 infection (SARS-COV-2). We will conduct an open-ended, uncontrolled clinical trial in 35 male and female patients, between 25-80 years of age with previous confirmed diagnosis of COVID-19 infection with negative nasopharyngeal polymerase chain reaction assay (PCR) test and without active disease, patients will also continue with their usual treatment. Clinical findings and laboratory and cabinet tests include a basal and 14-day metabolic and inflammatory profile, body weight, body mass index (BMI) and blood pressure will be determined during the initial and final visit, as well as respiratory parameters by pulmonary function tests (spirometry, TLCo) and performing the 6 min walk test in endless band with pre- and post-walk oximetry measurements at the beginning and end of the study. Adverse events to treatment will be documented. Statistical analysis: Mann-Whitney U test and Wilcoxon exact test. A p <0.05 shall be considered statistically significant.

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