Incidence and risk factors for long COVID in children with COVID‐19 pneumonia

Abstract Background and Objective There are only a few reports of long COVID including pulmonary function in children after COVID‐19 pneumonia. We determined the incidence of long COVID and abnormal pulmonary function in those children and identify risk factors. Methods This cohort study enrolled children admitted with COVID‐19 pneumonia during 2021–2022. We gathered clinical characteristics during admission and at follow‐up 3 months after. Results We determined the incidence of long COVID at 39.7% (95% confidence interval CI: 30.7%–49.1%). All severe pneumonia cases consistently reported persistent symptoms. Exercise intolerance, cough, and fatigue were the three most common persistent symptoms in 26 (22.4%), 21 (18.1%), and 18 (15.5%) of the patients, respectively. At the follow‐up, 21 cases (18.1%) demonstrated persistent abnormal chest radiographs. Three cases (6.9%) demonstrated restrictive ventilatory defects. Among those, one case (2.3%) demonstrated concomitant diffusion defect. Three cases (6.0%) demonstrated exercise‐induced hypoxemia after the 6‐minute walk test. Comparing spirometry variables between children with long COVID and without revealed significant difference of FEF25‐75 ( z score) between two groups. Age adjusted OR (95% CI): 1.13 (1.05–1.22), p value 0.002, allergic diseases adjusted OR (95% CI): 4.05 (1.36–12.06), p value 0.012, and living in polluted areas adjusted OR (95% CI): 2.73 (1.18–6.33), p value 0.019 were significantly associated with long COVID. Conclusion A significant percentage of children developed long COVID after COVID‐19 pneumonia. We should give additional attention to those who have exercise intolerance, chronic cough, or fatigue, especially older children, severe cases, children with allergic diseases, and those living in polluted areas.