Scars from the pandemic: understanding post-COVID-19 interstitial lung disease

Five years after the COVID-19 pandemic, the world continues to record acute cases of COVID-19 infection and witness its residual effects. Lung injury persisting beyond the resolution of acute viral pneumonia has been a known entity since the severe acute respiratory syndrome outbreak in 2005. However, residual interstitial lung disease (ILD) secondary to COVID-19 infection has become a new entity of interest due to the widespread and global impact of COVID-19. Post-COVID-19 ILD (PC-ILD) has emerged as a unique entity with age, male sex, smoking and the severity of acute illness as risk factors. Using current evidence, we discuss possible mechanisms for disease occurrence and the genetic similarities between PC-ILD and idiopathic pulmonary fibrosis. Characteristic radiographic findings, pulmonary function abnormalities and potential therapies are also discussed. As the world moves away from the acute phase of the pandemic, obtaining information on the long-term consequences of this disease becomes even more crucial. Continued research in this field is vital to guide decisions and obtain better outcomes in treatment and follow-up.