Medium‐term pulmonary outcomes (<6 months) after pediatric COVID‐19 infection evaluated using impulse oscillometry and spirometry

OBJECTIVE: Although coronavirus disease 2019 (COVID-19) usually exhibits a mild clinical course in children, concerns remain regarding persistent airway dysfunction after recovery. This study aimed to evaluate pulmonary function tests (PFTs) in children following mild COVID-19 infection and to compare the findings with those of healthy controls. METHODS: In this prospective cross-sectional study, children aged 6-18 years with polymerase chain reaction-confirmed COVID-19 infection were identified retrospectively from February 2022 and evaluated prospectively between June and December 2022. Fifty-eight post-COVID-19 patients and 56 age- and sex-matched healthy controls were included, and their demographic and clinical characteristics were recorded. PFTs were assessed using impulse oscillometry (IOS) followed by spirometry. RESULTS: There were no significant differences in demographic and anthropometric measurements between the post-COVID-19 group and the healthy controls. In terms of IOS measurements, zR5 and R5-20 (reflecting airway resistance) were higher and zX5 and zX20 (reflecting airway reactance) were lower in the post-COVID-19 group (p = .006, p = .002, p < .001, and p = .001, respectively). No significant differences were observed in spirometric parameters, including zFEV1, zFVC, zFEV1/FVC, and zFEF25-75. Notably, three patients exhibited persistent cough and dyspnea after COVID-19, had FEV1 values <90% predicted, positive bronchodilator reversibility, and inhalant allergen sensitization despite having no prior history of asthma or allergic rhinitis. CONCLUSION: Children recovering from mild COVID-19 infection may exhibit persistent airway dysfunction detectable by IOS despite normal spirometric findings. IOS appears to be a sensitive tool for identifying subclinical airway involvement in children following COVID-19.