Abstract / Description
BackgroundAcute respiratory tract infections (ARTIs) remain a major global health burden. Southwest China, with its complex geography and climate, represents a critical region for respiratory pathogen ecology. This study aimed to characterize the epidemiological dynamics of nine respiratory pathogens among ARTI patients in Southwest China across the pre-COVID-19 period (January 2019 to December 2019), the COVID-19 non-pharmaceutical interventions (NPIs) period (January 2020 to December 2022), and the post-NPIs period (January 2023 to December 2023).MethodsA multicenter, retrospective study was conducted from January 2019 to December 2023, including 240,611 ARTI patients. Serum IgM antibodies against nine pathogens: Influenza A virus (FluA), Influenza B virus (FluB), Respiratory syncytial virus (RSV), Parainfluenza Virus (PIV), Adenovirus (ADV), Mycoplasma pneumoniae (MP), Chlamydia pneumoniae (CP), Legionella pneumophila (LP), and Coxiella burnetii (Q fever, QF) were detected by indirect immunofluorescence assay, and the findings were interpreted as serological positivity/recent exposure signals rather than definitive microbiological confirmation of acute infection. Epidemiological characteristics and temporal trends were analyzed using descriptive statistics and Join-Point regression.ResultsMonthly serological positivity rates showed a marked decline during the early phase of the NPIs period. However, the overall serological positivity rate surged to 30.07% in the post-NPIs period, significantly higher than the pre-COVID-19 (27.83%) and NPIs (27.87%) periods (pā