Retrospective Analysis of Clinical Characteristics and Prognostic Factors in Hospitalized Pneumonia Patients from April 2023 to April 2026. Background: Pneumonia remains the leading cause of death from infectious diseases in adults worldwide, with an increasingly severe disease burden exacerbated by population aging and the frequent emergence of drug-resistant bacteria; in China, severe pneumonia accounts for a striking 13.58% to 20.05% of hospitalized cases. In recent years, shifts in the pathogen spectrum (e.g., COVID-19, influenza A) and patient demographic characteristics have posed new challenges for clinical management. However, existing studies mostly focus on single pathogens or specific populations (e.g., ICU patients), lacking systematic analyses of the full-disease course characteristics of general hospitalized pneumonia patients. Furthermore, in the post-pandemic era, the clinical phenotypes, treatment responses, and prognostic factors of pneumonia may have evolved, necessitating evidence-based support from real-world data. This study aims to conduct a retrospective analysis to clarify the epidemiological characteristics, etiological distribution, and prognostic factors influencing current hospitalized pneumonia patients, thereby providing a basis for optimizing diagnosis and treatment strategies.