Introduction:
Accumulated evidence suggests that pulmonary fibrosis is a common complication of COVID-19. Fibrotic post-coronavirus lung changes are similar to the changes found in patients with idiopathic pulmonary fibrosis.

Aim:
The paper describes the outcomes of pirfenidone usage in treatment of patients with post-coronavirus pulmonary fibrosis.

Case study:
The paper presents a case study about a 51-year-old male patient, who had diffuse post-coronavirus pulmonary fibrosis with significant impairment of external respiratory function. The patient had experienced severe COVID-19 bilateral polysegmental pneumonia. In the 3rd week of the disease, multislice computed tomography detected signs of fibrosis that affected 80% of lung tissue. It was decided to start antifibrotic treatment with pirfenidone, which is usually used to treat idiopathic pulmonary fibrosis.

Results and discussion:
Pirfenidone was prescribed for 3 months according to the conventional scheme in combination with methylprednisolone. This therapy resulted in significant decrease of fibrosis scope , normalization of respiratory function and improvement of patient's quality of life. A key feature of the presented clinical case is a significant positive effect of pirfenidone in treating coronavirus-associated pulmonary fibrosis, which affected 80% of lung tissue of the patient.

Conclusions:
Post-coronavirus pulmonary fibrosis is characterized by the severe oxygen insufficiency and requires a constant oxygen support. The treatment that included pirfenidone in combination with steroids has demonstrated convincing positive effect. It reduces post-coronavirus pulmonary fibrosis and improves lung function.