Longitudinal epidemiology of respiratory viruses in hospitalized patients in Oman (2017-2025)

Respiratory virus epidemiology in hospitalized patients is influenced by host susceptibility, seasonality, and health system disruptions; however, longitudinal patterns across major population-level events remain incompletely defined.

We conducted a single-center longitudinal study of 6776 hospitalized patients in Oman from 2017 to 2025. Respiratory viruses were detected using multiplex real-time PCR and analyzed descriptively by age group, season, and epidemiological period (pre-pandemic, pandemic, post-pandemic), without adjustment for testing intensity over time. Viral co-infections and fatal cases with bacterial, fungal, and viral co-pathogens were assessed.

Rhinovirus was the most frequently detected pathogen (44.9%) and circulated across all age groups and time periods. Other common viruses included respiratory syncytial virus, influenza A (H1N1pdm09 and H3N2), adenovirus, parainfluenza viruses, human metapneumovirus, and seasonal coronaviruses, each showing distinct age-specific and seasonal distributions. Viral co-infections occurred in 1482 cases (21.9%) and were strongly age-dependent, although the clinical significance of co-detection could not be determined. Viral circulation was substantially altered during the pandemic, with marked suppression of influenza followed by incomplete recovery, while rhinovirus and adenovirus remained relatively stable. Most viruses peaked in autumn and winter, whereas rhinovirus circulated year-round. A total of 150 of 6776 patients (2.2%) had fatal outcomes. Bacterial (58.0%) and fungal (26.0%) co-pathogens were frequently identified, although temporal and causal relationships with viral infection could not be established. Viral co-pathogens were less common; cytomegalovirus was the most frequently detected viral co-pathogen.

Respiratory virus epidemiology in this study is structured by age, seasonality, and major pandemic-related disruption. Frequent viral co-infections and the predominance of bacterial and fungal pathogens in fatal cases suggest that severe respiratory illness is frequently associated with polymicrobial detection, particularly in vulnerable hosts.