Influenza-Associated Hospitalizations During a High Severity Season — Influenza Hospitalization Surveillance Network, United States, 2024–25 Influenza Season
Year: 2025
Type: article
Study design: Observational Study
Abstract: The U.S. 2024-25 influenza season was a high-severity season characterized by co-circulation of influenza A(H1N1)pdm09 and A(H3N2) viruses. Data from the Influenza Hospitalization Surveillance Network covering 9% of the U.S. population, were analyzed to compare laboratory-confirmed influenza-associated hospitalization rates and patient clinical characteristics from the 2024-25 season with data from past seasons. Based on preliminary data from influenza-associated hospital admissions from October 1, 2024, through April 30, 2025, the cumulative influenza-associated hospitalization rate (127.1 influenza-associated hospitalizations per 100,000 population) had surpassed all end-of-season rates during the period beginning with the 2010-11 season. Cumulative 2024-25 season rates were highest among persons aged ≥75 years (598.8). Across age groups, hospitalization rates during the 2024-25 season were 1.8 to 2.8 times higher than median historical rates during the period beginning with the 2010-11 season. Among hospitalized patients, 32.4% had received an influenza vaccine, and 84.8% received antiviral treatment, though children and adolescents aged 5-17 years had the lowest proportion of antiviral receipt (61.6%). Similar to past seasons, most patients hospitalized with influenza during the 2024-25 season (89.1%) had one or more underlying medical conditions, 16.8% were admitted to an intensive care unit, 6.1% received invasive mechanical ventilation, and 3.0% died in hospital. Seasonal influenza viruses can cause severe disease, particularly among persons who are at higher risk for complications. CDC recommends that all persons aged ≥6 months who do not have contraindications receive an annual influenza vaccine and that all hospitalized patients with influenza receive timely antiviral treatment to reduce the risk for complications.
Authors: Alissa O’Halloran, Jennifer Whitmill Habeck, Matthew Gilmer, Ryan Threlkel, Shua J. Chai, Brenna Hall, Isaac Armistead, Nisha B. Alden, James Meek, Kimberly Yousey-Hindes, Kyle P. Openo, Lucy S. Witt, Maya L. Monroe, Patricia A. Ryan, Lauren Leegwater, Sue Kim, Melissa McMahon, Ruth Lynfield, Khalil Harbi, Murtada Khalifa, Caroline McCahon, Grant Barney, Bridget J. Anderson, Christina B. Felsen, Brenda L. Tesini, Nancy E. Moran, Denise Ingabire-Smith, Melissa Sutton, M. Andraya Hendrick, William Schaffner, H. Keipp Talbot, Andrea George, Hafsa Zahid, Shikha Garg, Catherine H. Bozio
Language: English
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
Funders: U.S. Department of Health and Human Services, National Foundation for Infectious Diseases, Minnesota Department of Health, Yale University, Council of State and Territorial Epidemiologists, Emory University, Colorado Department of Public Health and Environment, Michigan Department of Health and Human Services, Centers for Disease Control and Prevention, School of Medicine, Emory University, Abbott Diagnostics, National Center for Immunization and Respiratory Diseases
OpenAlex ID: W4414123819