Cross-sectional study of respiratory virus infections in upper respiratory tract infection patients: post-COVID-19 pandemic trends in Sichuan, China

Objectives Post-COVID-19 respiratory infection patterns require updated epidemiological data. To investigate the prevalence and infection patterns of upper respiratory tract infections (URTIs), a survey was conducted to assess the presence of influenza A (IFV A), influenza B (IFV B), respiratory syncytial virus (RSV), human rhinovirus (HRV), adenovirus (Adv), and SARS-CoV-2 among outpatients diagnosed with URTIs. Design A community-based cross-sectional study. Setting Three cities in Sichuan, China. Participants 1174 outpatients diagnosed with URTIs from December 2023 to February 2024. Methods Oropharyngeal swabs were collected using sterile flocked swabs, preserved at 4°C and analysed within 24 hours. Viral nucleic acid was extracted automatically and detected via multiplex PCR-melting curve analysis. Results Results showed in positive detection rates varied significantly by age (p<0.001), peaking in children (77.42%), followed by adolescents (73.23%), adults (63.59%) and older adults (57.58%). IFV B and A predominated, followed by HRV, Adv, RSV and SARS-CoV-2. 12 co-infection types were identified, with HRV/Adv and IFV B/HRV most prevalent. In children and adolescents, co-infections were significantly more common, with predominant types including HRV/Adv, HRV/RSV and RSV/IFV B. Conclusions This study reveals persistent influenza dominance and age-stratified co-infection risks and provides critical baseline data for optimising respiratory infectious disease control in the post-pandemic era.