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.