Jan 5 (Reuters) – Seasonal influenza activity remained elevated and rose in the final week of December, U.S. Centers for Disease Control and Prevention data showed on Monday, as the agency for the first time classified the 2025-26 season as “moderately severe.”
CDC estimates the season’s toll so far at least 11 million illnesses, 120,000 hospitalizations and 5,000 deaths. In the 2024–25 season, CDC estimated at least 5.3 million illnesses, 63,000 hospitalizations and 2,700 deaths in the week ended December 28, 2024.
Public health experts told Reuters last week that holiday travel, low vaccination rates and misinformation contributed to the surge in cases.
CDC said flu activity will likely continue for several weeks.
Influenza A(H3N2) remains the dominant strain, accounting for more than 91% of subtyped influenza A cases, CDC said.
Among 389 influenza A(H3N2) viruses collected since September 28, 2025, and genetically characterized at CDC, 90.5% belonged to subclade K, a variant of A(H3N2).
Hospitals admitted about 33,301 influenza patients in the week ended December 27, up sharply from earlier weeks, CDC data showed.
Outpatient visits for respiratory illness rose to 8.2% of healthcare visits, above seasonal baselines.
CDC reported one flu-related pediatric death last week, bringing the 2025-26 season total to nine.
Experts acknowledged a mismatch between the vaccine and circulating strains but said vaccination should still reduce the risk of severe disease. About 130 million doses of flu vaccine have been distributed in the United States this season.
(Reporting by Siddhi Mahatole in Bengaluru; Editing by Tasim Zahid)
