This project aims to perform surveillance for severe influenza-associated encephalopathy (IAE) in hospitalized children under 18 years with confirmed influenza, using standardized case definitions. It involves collecting detailed clinical data to assess risk factors, disease course, and the impact of interventions like vaccination and antivirals. A key component is assessing patient vaccination status through medical record and statewide vaccine registry reviews. The work will be performed in the state of Minnesota. The total estimated budget for this project is $1,500,000.