Impact of the corona virus disease 2019 pandemic on the prevalence of common respiratory pathogens in hospitalized young patients with non-severe community-acquired pneumonia.

Background: Community-acquired pneumonia (CAP) remains a significant global health concern, yet the characteristics of non-severe CAP in young adults, particularly following the corona virus disease 2019 (COVID-19) pandemic, are not well elucidated. This study aimed to investigate the impact of COVID-19 infection on the epidemiological trends of common respiratory pathogens in young patients with non-severe CAP and to provide a theoretical basis for treatment protocols. Methods: A retrospective analysis was conducted on data from all young CAP patients hospitalized at The Third Affiliated Hospital of Guangzhou Medical University from January 2018 to December 2023. The respiratory pathogen profiles of young CAP inpatients were compared across three periods: pre-pandemic (January 2018 to December 2019), during the pandemic (January 2020 to December 2022), and post-pandemic (January 2023 to December 2023). Descriptive statistical analysis was used to evaluate the epidemiological characteristics, infection seasonality, and patterns of CAP patients. The Chi-squared or Fisher's exact test was used to compare the differences in pathogen positivity rates and co-infection rates among different stages. Results: There were no significant differences in age, white blood cell count, neutrophil count, lymphocyte count, and C-reactive protein (CRP) among the three groups of young non-severe CAP inpatients. The proportion of males showed statistical significance among the three groups: pre-pandemic (12.5%), during the pandemic (28%), and post-pandemic (23.23%). The proportion of young CAP inpatients to total CAP inpatients also differed significantly: pre-pandemic (17.75%), during the pandemic (11.93%), and post-pandemic (23.77%). Changes in pathogen profiles were as follows: bacterial infection rates-pre-pandemic (6.25%), during the pandemic (10%), post-pandemic (21.38%); viral infection rates-pre-pandemic (10.94%), during the pandemic (19%), post-pandemic (23.90%); Mycoplasma infection rates-pre-pandemic (56.25%), during the pandemic (46%), post-pandemic (35.22%); co-infection rates-pre-pandemic (7.81%), during the pandemic (13%), post-pandemic (20.75%). These differences were statistically significant among the three groups. The rate of bacterial-bacterial co-infections significantly increased: pre-pandemic (20%), during the pandemic (53.85%), and post-pandemic (72.72%), with significant differences among the three groups. The top five pathogens in each stage were pre-pandemic- Conclusions: Following COVID-19 infection, the incidence of CAP in young people increased, with changes in pathogen profiles. There was an increase in bacterial and viral infections, a significant rise in co-infections, predominantly bacterial-bacterial infections, and more atypical pathogen infections were observed.