Clinical characteristics, pathogen detection, and severity markers among children with acute respiratory infections during the COVID-19 restriction period: a retrospective hospital-based study

Background The epidemiology of pediatric acute respiratory infections (ARIs) changed substantially during the COVID-19 (coronavirus disease 2019) pandemic, largely because of school closures, masking, reduced travel, and other non-pharmaceutical interventions (NPIs). However, hospital-based data from the restriction period remain useful for describing pathogen detection patterns, clinical severity, and markers of adverse clinical course. Methods We conducted a retrospective hospital-based study of 62 children aged <18 years who were evaluated for ARI symptoms and underwent real-time fluorescent quantitative nucleic acid testing for common respiratory pathogens, including respiratory viruses and Mycoplasma pneumoniae . Demographic, clinical, laboratory, treatment, severity, and outcome variables were extracted from medical records. Continuous variables were summarized using medians and ranges, and group comparisons used non-parametric tests. Given the small sample size and sparse severe-outcome events, the study was not powered to detect small effect sizes, and regression findings were interpreted conservatively as hypothesis-generating rather than confirmatory. Results The median age was 9 years (range, 1–17), and 33 patients (53.2%) were female. Most children had mild disease (37/62, 59.7%); 19 (30.6%) had moderate disease and 6 (9.7%) had severe disease. Intensive care unit (ICU) admission was recorded in 6 patients (9.7%), and mechanical ventilatory or noninvasive respiratory support in 9 (14.5%). Fever (43.5%) and cough (22.6%) were the most frequent presenting symptoms. Median oxygen saturation was 94.7% (range, 87.2–97.8). Respiratory virus detection was documented in 15 children (24.2%). Human rhinovirus was detected in 15 children (24.2%), human bocavirus in 9 (14.5%), and Mycoplasma pneumoniae in 10 (16.1%); co-detection was recorded in 14 children (22.6%). Lower SpO2 and longer symptom duration differed significantly across severity categories (both p < 0.001). In exploratory logistic regression, each additional day of symptoms was associated with higher odds of hospital admission/continued inpatient management [odds ratio [OR], 1.4; 95% confidence interval [CI], 1.03–1.93; p = 0.022]. Sex was not significantly associated with clinical severity or laboratory parameters. Conclusions In this small hospital-based pediatric ARI cohort during the COVID-19 restriction period, severe disease was uncommon, and oxygen saturation and symptom duration were the most clinically coherent markers of greater severity. The observed pathogen detection pattern is compatible with pandemic-era disruption of respiratory pathogen circulation, but causal conclusions about NPIs require larger denominator-based studies with pre-pandemic and post-restriction comparison groups.