Prevalence, spectrum, and the relations between short-term and long-term post-acute sequelae of COVID-19 in children

Background. Data on the prevalence of post-COVID-19 condition (PCC) in children differ due to the lack of specific diagnostic criteria, reliable biomarkers, and limitations of many studies. It is important to study the association between PCC, previous functional disorders, and any events in the post-acute period of COVID-19 to estimate the true burden of PCC in children. The aim. To determine of the prevalence of PCC in relation to initial functional disorders in children during the year after a mild form of COVID-19 and acute respiratory tract infections (ARTI) of other etiologies. Materials and methods. The prospective study using a continuous sampling method included children under 18 years of age hospitalized with suspected COVID-19, in whom COVID-19 was confirmed by RT-PCR (n = 121) or excluded by molecular and serological methods (ARTI group, n = 105). Information on patients was collected from September 2020 to December 2021 by questionnaires at index points: hospital discharge and after 1, 3, 6 and 12 months. Severe COVID-19 and patients with chronic diseases were excluded. Functional disorders in the anamnesis and any events associated with health disorders during the year of observation, the severity of symptoms were taken into account. The analysis was performed in groups of children 6 years and ≥ 6 years of age. Symptoms were grouped into clusters. Results. Any symptoms were identified with a frequency of 32–39% (in children 6 years and ≥6 years, respectively). The most common were psycho-emotional, respiratory and autonomic dysfunction (AD) cluster. Symptoms in most cases were mild with a duration of 3–6 months. After adjustment for age, AD history and recurrent ARTI episodes, no difference was found in the symptom clusters prevalence between confirmed and excluded COVID-19, except for hyposmia, the incidence of which in children ≥6 years decreased from 14.3% at the first index point to 2.4% after one year. Among patients without an AD history and without recurrent ARTI during the year, de novo PCC was a rare phenomenon (2.7–8.0%) without differences between COVID-19 and controls. The risks of PCC were significantly increased in patients with an AD history (adjusted OR at 1 month 3.19 (95% CI 1.89–5.38), at 6 months 3.33 (95% CI 1.81–6.15)). Multiple (5–25) and persistent (at all index points) symptoms rated by patients as significant occurred de novo rarely (1.7% (95% CI 0.4–4.9)), but significantly more often in children with an AD history — 25%) 95% CI 13.6–39.6%) (difference 23.3% (10.9–35.7%), OR 14.8 (4.4–50.6), p 0.001). Recurrent episodes of ARTI were an important risk factor for an increase in cognitive cluster complaints and vagotonic AD after 3–6 months of observation. Conclusion. The results obtained indirectly support the concept that PCC is a somatoform functional disorder, probably of sociogenic nature, in patients who are anxious at baseline. Some patients with the COVID-19 and ARTI consequences really need medical and psychosocial rehabilitation. The study of PCC provides new insights into the consequences of widespread respiratory viral infections.