Age and Department-Specific Respiratory Viral Patterns During the COVID-19 Era: A Four-Year Hospital Analysis

Shan Hong¹Maoshu Zhu¹Yanqian Huang²Linlin Chen¹Dandan Han¹Wenliu Qiu¹Shujing Li¹Linghui Ding¹Heping Zheng¹Feng Guo³Jun Mi¹Xiuli Li¹Jie Chen²Dongjie Li²Liangneng Zou¹Yanli Wei^1*

• ¹Xiamen Fifth Hospital, Xiamen, China
• ²Community Health Service Center, Maxiang Street, Xiang'an District, Xiamen, China
• ³Xiang 'an District Center for Disease Control and Prevention, Xiamen, China

Background: The COVID-19 pandemic significantly transformed global respiratory pathogen circulation dynamics. This investigation examines respiratory viral epidemiological characteristics in a Chinese hospital environment throughout the pandemic and subsequent recovery phases. Methods: We performed comprehensive surveillance monitoring of 9,237 patients undergoing diagnostic testing for 13 respiratory pathogens at Xiamen Fifth Hospital from January 2020 through early 2024. Patients were stratified by age groups (pediatric, adult, geriatric) and hospital departments (pediatric-predominant, adult-predominant, geriatric-predominant, mixed-population). Multivariable analyses were conducted to identify independent risk factors and temporal trends. Results: Among 9,237 patients tested over four years, human rhinovirus was most prevalent (13.5% overall) with pronounced age stratification (children 17.4%, adults 9.3%, elderly 5.9%), while Mycoplasma pneumoniae ranked second (8.0%) with extreme pediatric predominance (children 11.6% vs. elderly 0.9%). Pandemic-era dynamics revealed dramatic temporal shifts: widespread 2020 suppression, RSV resurgence in 2021 with uniform high rates across all age groups, explosive IAV resurgence in 2022 (elderly 31.2%), and MP's remarkable 2023 emergence after near-complete absence during 2020-2022. Co-infection rates increased progressively with age (children 22.14%, adults 16.37%, elderly 13.31%), with IBV-hMPV showing the strongest positive association and HRV demonstrating negative associations suggesting viral interference. Among 55 hospital departments classified by patient demographics, multivariate logistic regression revealed distinct risk patterns: children-dominant departments showed markedly elevated risks for classic pediatric pathogens including RSV (OR = 11.76) and dramatic MP surges in 2023 (OR = 18.95), while adult-dominant departments had higher IAV risk with substantial 2022 increases. The 13 pathogens clustered into three epidemiologically distinct groups reflecting different transmission patterns and clinical associations across hospital environments. Conclusions: This surveillance study reveals distinctive post-pandemic respiratory pathogen patterns characterized by age-specific and department-specific distributions that extend beyond traditional demographic risk factors. These findings inform targeted infection prevention strategies and surveillance optimization in healthcare settings.