Influenza Activity in the U.S. Key Points: - Nationally, percent positivity for influenza remained stable this week compared to last week but has been increasing slightly over the past several weeks.
- The percentage of emergency department visits for influenza increased among pediatric age groups.
- During Week 47, of the 409 influenza viruses reported by public health laboratories, 394 were influenza A and 15 were influenza B. Of the 281 influenza A viruses subtyped during Week 47, 141 (50.2%) were influenza A(H1N1)pdm09, 140 (49.8%) were A(H3N2).
- Two confirmed human infections with influenza A(H5) viruses were reported to CDC this week. To date, human-to-human transmission of avian influenza A(H5) virus has not been identified in the United States.
- CDC recommends that everyone ages 6 months and older get an annual influenza (flu) vaccine.
- There are prescription flu antiviral drugs that can treat flu illness; those should be started as early as possible and are especially important for patients at higher risk for flu-related complications.
- Influenza viruses are among several viruses contributing to respiratory disease activity. CDC has provided updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.
Below is a summary of the key influenza indicators for the week ending November 23, 2025:
Viral Surveillance - Clinical Lab: The percentage of respiratory specimens testing positive for influenza at clinical laboratories is 2.5% this week. Viral Surveillance - Public Health Lab: Influenza A(H1N1)pdm09 and A(H3N2) viruses were co-circulating this week. Virus Characterization: Influenza virus characterization information can be found here: U.S. Influenza Surveillance: Purpose and Methods | CDC
Outpatient Illness: The percentage of patient visits to a health care provider for respiratory illness in Week 47 was 3% which is at baseline. Outpatient Respiratory Illness: ILINet Activity Map: Four jurisdictions experienced moderate ILI activity and 2 jurisdictions experienced high or very high ILI activity in Week 47. Laboratory-Confirmed influenza Hospitalizations can be found here: Laboratory-Confirmed Influenza Hospitalizations (cdc.gov) The weekly hospitalization rate observed in Week 47 was 0.3 per 100,000 population. The cumulative hospitalization rate was 1.6 per 100,000 population.
Influenza-Associated Pediatric Deaths: Zero influenza-associated deaths have been reported so far this season. For more information: https://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html CDC FluView Site https://www.cdc.gov/fluview/
Influenza Activity in Massachusetts For more information about flu, please go to our Viral Respiratory Disease Dashboard which includes information not only on influenza but also other acute respiratory diseases, COVID-19, and respiratory syncytial virus (RSV), wastewater data and immunizations for respiratory diseases.
The figure below shows that for MMWR week 47, the percent of ILI visits in the current week is below the regional baseline of 2.2%. (The CDC uses trends from past years to determine a region-specific baseline rate of ILI visits, which for Massachusetts is 2.2%. A rate above this regional baseline indicates higher than normal levels of ILI in the state.) For more information on how regional baselines are calculated see CDC’s influenza surveillance website at U.S. Influenza Surveillance: Purpose and Methods | FluView | CDC) For more information on weekly flu activity, see CDC’s influenza surveillance website at https://www.cdc.gov/fluview/surveillance/index.html. |