Objective To analyze the clinical and epidemiological characteristics of severe influenza cases in a province of China, so as to provide scientific evidence for the prevention and control, early identification, and optimized diagnosis and treatment of severe influenza. Methods A retrospective collection of data on 326 severe influenza cases reported by the provincial Center for Disease Control and Prevention (CDC) and medical institutions from January 2021 to December 2024 was conducted. Statistical analyses were performed on their epidemiological distribution, clinical symptoms, laboratory indicators, complications, and prognosis. Results Among the 326 severe cases, 189 (58.0%) were male and 137 (42.0%) were female. People aged ≥60 years accounted for 43.6% and children aged ≤5 years accounted for 23.9%, making them the high-incidence groups. The peak incidence was concentrated from December to February of the following year (66.6%), and the main pathogens were influenza A (H1N1) (46.9%) and influenza A (H3N2) (36.2%). The main clinical symptoms were persistent high fever, cough, and dyspnea. Common complications included pneumonia and acute respiratory distress syndrome. The case fatality rate was 8.9%, and most deaths were complicated with underlying diseases and severe complications. Conclusion Severe influenza cases in this province show significant seasonal and population-specific characteristics. The elderly, children, and patients with underlying diseases are high-risk groups. Early identification and timely antiviral treatment are the key to reducing the case fatality rate.

Influenza, Severe Cases, Clinical Characteristics, Epidemiological Characteristics, A Certain Province