Weekly US Influenza Surveillance Report: Key Updates for Week 5, ending February 1, 2025 | FluView – CDC
Source: Cdc.gov
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All data are preliminary and may change as more reports are received.
Directional arrows indicate changes between the current week and the previous week. Additional information on the arrows can be found at the bottom of this page.
A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.1
Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.
• Seasonal influenza activity remains elevated and continues to increase across the country.
• During Week 5, of the 4,377 viruses reported by public health laboratories, 4,264 were influenza A and 113 were influenza B. Of the 3,458 influenza A viruses subtyped during Week 5, 1,857 (53.7%) were influenza A(H1N1)pdm09, 1,601 (46.3%) were A(H3N2), and 0 were A(H5).
• Outpatient respiratory illness is increasing and remains above baseline nationally for the tenth consecutive week. All 10 HHS regions are above their region-specific baseline.
• One human infection with an influenza A(H1N2) variant (A(H1N2)v) virus was reported.
• No new influenza A(H5) cases were reported to CDC this week. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States.
• Ten pediatric deaths associated with seasonal influenza virus infection were reported this week, bringing the 2024-2025 season total to 57 pediatric deaths.
• CDC estimates that there have been at least 24 million illnesses, 310,000 hospitalizations, and 13,000 deaths from flu so far this season.
• CDC recommends that everyone ages 6 months and older get an annual influenza (flu) vaccine.1
• 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 severe illness.2
• Influenza viruses are among several viruses contributing to respiratory disease activity. CDC is providing updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.
Nationally and in all 10 HHS regions, the percentage of respiratory specimens testing positive for influenza virus in clinical laboratories increased (change of ≥ 0.5 percentage points) compared to the previous week. Region 6 had the highest percent positivity (37.8%) and Region 10 had the lowest (26.1%). Influenza A(H1N1)pdm09 and A(H3N2) were the predominant viruses reported this week. For regional and state level data and age group distribution, please visit FluView Interactive. Viruses known to be associated with recent receipt of live attenuated influenza vaccine (LAIV) or found upon further testing to be a vaccine virus are not included, as they are not circulating influenza viruses.
The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza virus) are used to monitor whether influenza activity is increasing or decreasing.
The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating influenza viruses that belong to each influenza subtype/lineage.
*These data reflect specimens tested, and the number determined to be positive for influenza viruses at the public health labs (specimens tested is not the same as cases). The data do not reflect specimens tested only at CDC and could include more than one specimen tested per person. The guidance for influenza A(H5) virus testing recommends testing both a conjunctival and respiratory swab for people with conjunctivitis which has resulted in more specimens testing positive for influenza A(H5) virus than the number of human A(H5) cases. For more information on the number of people infected with A(H5) viruses, please visit the “How CDC is monitoring influenza data among people to better understand the current avian influenza A (H5N1) situation”
†When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant” influenza virus. Most human infections with variant influenza viruses occur following exposure to swine, but human-to-human transmission can occur. It is important to note that in most cases, variant influenza viruses have not shown the ability to spread easily and sustainably from human-to-human.
*This graph reflects the number of specimens tested and the number determined to be positive for influenza viruses at the public health lab (specimens tested is not the same as cases). It does not reflect specimens
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