Community-acquired pneumonia in children after the COVID-19 pandemic. What influences the course and outcomes?

Background: during the COVID-19 pandemic, the etiology of community-acquired pneumonia (CAP) has changed worldwide. Determination of serum cytokine levels in CAP has a diagnostic and prognostic value. Despite a high significance of CAP in children, diagnosis, treatment and prevention strategies are based on studies conducted in adults without adequately considering the specific etiology of the disease in pediatric populations. Aim: to determine prognostic signs of an unfavorable CAP course in children based on a serum cytokine assay data and the disease etiology in the post-pandemic period. Materials and Methods: 126 children aged from 1 month to 17 years 11 months with confirmed CAP (66 — non-severe CAP, 60 — severe CAP) were examined. Using direct and indirect diagnostic methods, CAP etiology was decoded in all the patients. Serum cytokines (IL-3, IL-6, IL-8, IL-12, IL-17F, IL-21, and TNFα) were assayed in 88 children (i. e., 73 patients with CAP and 15 healthy ones). Results: CAP was caused by viral (14.3%), bacterial (30.2% where Mycoplasma is 40.5%), viral + bacterial (41.3%) and unspecified (14.2%) pathogens. Viral (15.1%), bacterial (34.2%), and viral+bacterial (39.7%) pathogens of CAP were confirmed in respiratory discharge of children underwent the cytokine assay. Besides, pathogens were not isolated in 11.0% of the subjects. Severe (49.3%) and non-severe (50.7%) CAP was reported. In the group, mycoplasmal CAP was detected in 39.7% of subjects. The course of severe CAP was associated with increased production of both proinflammatory (IL-6, IL-8, IL-17F) and anti-inflammatory cytokines (IL-21) as compared to non-severe one. High levels of IL-8 and IL-17F were reported in patients with the bilateral CAP. High levels of IL-6, IL-8, and IL-12 were recorded in children with exudative pleuritis, and subjects with respiratory failure upon admission showed high TNFα levels. Viral CAP demonstrated the highest IL-17F levels. Typically, viral+bacterial CAP showed high IL-3 levels. Mycoplasmal CAP is associated with a lower IL-21 level than CAPs caused by other pathogens. Severe mycoplasmal CAP is coupled with higher IL-17F level than non-severe one. Conclusion: serum cytokine assay in children with CAP can be used to assess and predict the severity of the condition, the extent of lung damage, complications and etiology. Since viral pathogens were isolated in more than half of the examined children with CAP, and the study results demonstrate that involvement of viral agents in the disease etiology exacerbates systemic inflammation, there are good reasons to add antiviral therapy (in particular, to prevent complications). Keywords: community-acquired pneumonia in children, respiratory infections in children, serum cytokines, predictors of unfavorable course. For citation: Preobrazhenskaya D.V., Melekhina E.V., Sabinina T.S., Yatsyshina S.B. Community-acquired pneumonia in children after the COVID-19 pandemic. What influences the course and outcomes? RMJ. 2025;3:10–15. DOI: 10.32364/2225-2282-2025-3-2