Key Takeaways on Influenza Surveillance in the United States
As per the latest data released by the CDC regarding influenza surveillance in the United States, the following key points stand out:
1. Seasonal influenza activity remains elevated across the country.
2. Outpatient respiratory illness is above baseline nationally for the sixth consecutive week.
3. No new influenza A(H5) cases were reported this week.
4. Five pediatric deaths associated with seasonal influenza have been reported this week, bringing the total for the season to 16.
5. CDC estimates that there have been at least 9.1 million illnesses, 110,000 hospitalizations, and 4,700 deaths from flu so far this season.
6. Antiviral flu drugs are available and should be started early, especially for high-risk patients.
7. CDC recommends that everyone ages 6 months and older get an annual flu vaccine.
Influenza Virus Characterization and Susceptibility to Antiviral Medications
CDC has genetically characterized 803 influenza viruses collected since September 29, 2024. Antigenic characterization showed that most viruses were well-recognized by ferret antisera to the reference viruses.
Assessment of virus susceptibility to antiviral medications showed that most viruses tested had no decreased susceptibility to neuraminidase inhibitors or baloxavir.
Outpatient and Emergency Department Illness Surveillance
Nationally, outpatient visits for respiratory illness remained elevated. ILI activity was above baseline for the sixth consecutive week.
Hospitalization and Mortality Surveillance
FluSurv-NET data showed 7,096 laboratory-confirmed influenza-associated hospitalizations between October 1, 2024, and January 4, 2025. Cumulative hospitalization rates were highest among adults aged 65 years and older.
NCHS mortality surveillance data indicated an increase in the percentage of deaths due to influenza during the week ending January 4, 2025.
Additional Information
Additional virologic surveillance information is available on FluView Interactive. Other sources of influenza surveillance data include the National Institute for Occupational Safety and Health and state and local influenza surveillance reports.
Internationally, WHO and its collaborating centers provide global influenza surveillance information.
For a detailed understanding of the CDC influenza surveillance system, methodology, and data components, visit the surveillance methods page on the CDC website.