Long-term pulmonary complications following COVID-19 have been extensively described in the adult population. Unfortunately, data in children and adolescents are still scarce. Diagnoses of post-COVID syndrome refer to clinical features persisting for more than 12 weeks after acute COVID-19, which could not be explained by any alternative diagnosis.
Chronic cough, chest tightness, nasal symptoms and exertional dyspnoea are the most common persistent respiratory symptoms reported in children following acute COVID-19 infection. However, most symptoms are self-limiting and tend to resolve by 12 weeks. The time to improvement depends on the premorbid condition and the severity of the illness.
The pathophysiology of pulmonary complications post COVID-19 is not precisely known. It may occur due to direct damage to the respiratory system or other system involvement (cardiac or rheumatological). The postulated mechanisms are lung damage due to the initial infection, ongoing virus-host interaction, persistent hyper-inflammation, poor antibody response, and/or an exaggerated immune response leading to autoimmunity.
Follow-up studies on small cohorts of these children have shown only a minority with persistent pulmonary function abnormality and a few case reports of post-infectious bronchiolitis obliterans following acute COVID-19 have been reported.
Large cohorts with a longer duration of follow-up with standardised imaging and pulmonary function testing will be required to fully ascertain the long-term pulmonary complications of COVID-19 in children. Time will provide an advanced understanding for the prevention and appropriate care of long term pulmonary sequeale in the paediatric population.