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

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.