Respiratory pathogen epidemiology in the post-pandemic era: a multicenter retrospective study from Saudi Arabia

Post-COVID-19 respiratory pathogen dynamics remain incompletely characterized, particularly in the Arabian Peninsula. Understanding pathogen prevalence, co-infection patterns, and age- and season-specific trends is critical for informing diagnostic strategies, public health monitoring, and prevention strategies.

We conducted a retrospective, multicenter study across seven tertiary hospitals in three Saudi Arabian regions (Riyadh, Jeddah, Qassim), analyzing 23,074 respiratory samples collected from June 2024 to August 2025 using the QIAstat-Dx Respiratory SARS-CoV-2 Panel (QIAGEN, Hilden, Germany). Demographic, seasonal, and co-infection patterns were assessed and determinants of infection were evaluated. Age-specific and pathogen-specific odds ratios with 95% confidence intervals were calculated using multivariable logistic regression, adjusting for sex, region, and season, with adults aged 18-49 years as the reference group.

At least one respiratory pathogen was detected in 10,505 samples (45.5%). Single-pathogen infections predominated (88.1%), while co-infections were relatively uncommon (11.9%). Viral pathogens accounted for the majority of detections, with significant age- and region-specific differences identified in multivariable analysis. The most frequently detected pathogens included rhinovirus/enterovirus, influenza A, and RSV, whereas bacterial pathogens were infrequent. Children demonstrated significantly higher odds of adenovirus (adjusted OR 2.8, 95% CI 2.4-3.3), bocavirus (adjusted OR 6.1, 95% CI 4.9-7.6), and RSV (adjusted OR 4.2, 95% CI 3.8-4.7) compared to adults aged 18-49 years, while RSV detection was also elevated in older adults (≥65 years: adjusted OR 2.1, 95% CI 1.8-2.5). Detection rates varied significantly by season, with higher activity in winter and autumn and reduced activity during summer.

Contemporary respiratory infections in Saudi Arabia are dominated by viral pathogens, with age-specific and seasonal patterns resembling pre-pandemic epidemiology. These findings support targeted monitoring, age-stratified prevention strategies, and evidence-based resource allocation for respiratory disease management in the post-pandemic era.