Changes in spectrum of respiratory pathogens infections among hospitalized patients post COVID-19 pandemic in Jinan, Shandong Province

The patterns of respiratory pathogens have undergone significant changes, underscoring the critical need for accurate pathogen identification to guide targeted treatment. This study aimed to investigate the positive rates of common respiratory pathogens over the past two years using the multiplex molecular testing in clinical settings. This study evaluated respiratory pathogens in 7861 hospitalized patients at Qilu Hospital of Shandong University from March 2022 to February 2024. Pathogen detection was performed using multiplex RT-PCR combined with capillary electrophoresis technology, targeting influenza A virus (Flu-A), influenza A virus H1N1 (H1N1), influenza A virus H3N2 (H3N2), influenza B virus (Flu-B), parainfluenza virus (PIV), adenovirus (ADV), human Metapneumovirus (HMPV), human Coronavirus (HCOV), Mycoplasma pneumoniae (MP), respiratory syncytial virus (RSV), parainfluenza virus (PIV), Boca virus (Boca), human Rhinovirus (HRV), and Chlamydia (Ch). A comparative analysis of epidemiological patterns was conducted between the period during and after implementation of COVID-19 control policies. The overall pathogen detection rate was significantly higher at 65.79% (3786/5754) post COVID-19 pandemic compared to 30.36% (640/2107) during COVID-19 pandemic. With the relaxation of COVID-19 control policies, the positive rates of viruses such as Flu-A, Flu-B, PIV, RSV, and HCOV increased significantly. In contrast, there were no significant differences in the positive rates of HRV and Boca between the two periods. Notably, the positive rate of RSV was significantly higher across all age groups in the post-pandemic COVID-19 period, expect among individuals aged 14-18 and 19-40 years. MP was identified as the predominant pathogen in patients aged 4-13 years. Seasonal variation was evident in the detection rates of respiratory pathogens, ranging from 18.27% in 2022 to 77.79% in 2023. Flu-A H1N1 subtype infections were detected throughout spring, autumn and winter of 2023, peaking in spring and declining gradually in subsequent months. Additionally, MP infections fist emerged in May 2023 and increased monthly, reaching the peak in October of the same year. The findings illustrate the progressive re-emergence and considerable epidemiological importance of multiple respiratory pathogens among hospitalized patients across different age groups and seasons during the two-year surveillance period. Utilizing a multiplex molecular approach for respiratory pathogen surveillance enables accurate assessment of prevalence trends, especially in hospitalized patients with more severe clinical presentations, which can help clinicians to take necessary measures in the management of prevention, control, and precise therapy.