Hospital-Based Surveillance of Respiratory Pathogen Positivity and Distribution: A Six-Year Epidemiological Study in Beijing, 2020–2025

Objective: Respiratory tract infections (RTIs) are imposing a great economic burden, morbidity, and mortality on the healthcare system. Eleven common respiratory pathogens, based on age of onset, clinical setting, season and calendar year during and after the COVID-19 pandemic, were analyzed to optimize clinical diagnosis and prevention. Methods: In this retrospective cross-sectional study, respiratory pathogen testing results of 9882 samples from RTI patients from January 2020 to December 2025 were included to statistically analyze the positivity, distribution and trend of change. Multiplex PCR combined with capillary electrophoresis was used to simultaneously detect 11 respiratory targets. Results: The overall positive detection rate was 24.71%, with the top three pathogens being human rhinovirus (HRV) (6.20%), influenza A virus (InfA) (4.28%), and respiratory syncytial virus (RSV) (4.13%). The patients aged under 18 had the highest detection rates (≤6 years: 39.80%; 7 to 17 years: 37.95%). HRV, RSV and Mycoplasma pneumoniae (MP) were the primary pathogens among pediatric patients, while InfA was predominant in adults (including those >65 years). The 11 pathogens were most common in emergency department patients (29.14%), followed by outpatient patients (28.57%). InfA was the most predominant virus, followed by HRV and RSV, in the intensive care unit, emergency department, and outpatient settings. The detection rate was highest in autumn (33.22%), followed by winter (26.61%). MP had the highest rate in autumn, and InfA was the most frequent in winter. During the COVID-19 pandemic (2020–2022), the respiratory pathogen spectrum was dominated by HRV, RSV, and human parainfluenza virus (HPIV). And the prevalent pathogens shifted to InfA, MP and HRV during 2023–2025. Co-detections were observed in 8.03% of the positive cases, and 82.65% occurred in patients aged < 18 years. The dominant co-detections were HRV + MP, HRV + RSV and HRV + HPIV. Conclusions: The distribution of respiratory pathogens exhibited specific variations based on age, clinical setting, season, and calendar year, suggesting that differentiated prevention should be developed for different patients.