Announcement

**Commonground** · November 15, 2025, 06:10 AM

Respiratory Virus Activity Levels

For Everyone
NOV. 14, 2025

ABOUT
Provides an update on how COVID-19, influenza, and RSV may be spreading nationally and in your state.

Summary
This Week’s Activity Update:

Reported on Friday, November 14, 2025

The amount of acute respiratory illness causing people to seek health care is at low or very low levels in most states.
The percentage of RSV laboratory tests that are positive, and emergency department visits for RSV in many Southeastern and Southern states, are increasing.
Nationally, COVID-19 activity is low.
Seasonal influenza activity is low nationally but increasing.
Wastewater surveillance data for COVID-19, flu and RSV were last updated on September 25, 2025. Data will be updated on November 21, 2025.

Level of Respiratory Illness Activity

Respiratory illness activity is monitored using the acute respiratory illness (ARI) metric. ARI captures a broad range of diagnoses from emergency department visits for respiratory illnesses, from the common cold to severe infections like influenza, RSV and COVID-19. It captures illnesses that may not present with fever, offering a more complete picture than the previous influenza-like illness (ILI) metric. Refer to data notes for more details.

Wastewater Map

Wastewater (sewage) can be tested to detect traces of infectious diseases circulating in a community, even if people don't have symptoms. You can use these data as an early warning that levels of infections may be increasing or decreasing in your community. COVID-19 w astewater trends may differ from some health outcome findings, such as hospitalization trends, as COVID-19 is causing severe disease less frequently than earlier in the pandemic.

Influenza levels are for Influenza A only, which includes the avian influenza A(H5). Wastewater data cannot determine the source of viruses (from humans, animals, or animal products). Refer to data notes for more details, including important considerations for interpreting wastewater findings.

Wastewater surveillance data for these respiratory viruses were last updated on September 25, 2025. Data will be updated on November 21, 2025.

* Level based on a small segment (less than 5%) of the population and may not be representative of the state/territory. Read more »

Emergency Department Visits for Viral Respiratory Illness

Weekly percent of total emergency department visits associated with COVID-19, influenza, and RSV. Refer to data notes for more details.
Search for your state or your county to receive information on emergency department visits in your community
The CDC may not have data for all states, counties, or territories. Read more »

Epidemic Trends
CDC uses data from emergency department visits to model epidemic trends. This model helps tell whether the number of new respiratory infections is growing or declining in your state. While this model tells us the trend, it does not tell us the actual number of current infections of SARS-CoV2, the virus that causes COVID-19 or influenza virus. Refer to data notes for more details.

Percent of Tests Positive for Respiratory Viruses
Weekly percent of tests positive for the viruses that cause COVID-19, influenza, and RSV at the national level. Preliminary data are shaded in gray. Refer to data notesfor more details.

Respiratory Virus Activity Levels

https://www.cdc.gov/respiratory-viruses/data/activity-levels.html#cdc_data_surveillance_section_3-emergency-department-visits-for-viral-respiratory-illness

Updates on how COVID-19, Flu, and RSV may be spreading nationally and in your state

**Commonground** · November 22, 2025, 11:11 AM

Weekly US Influenza Surveillance Report: Key Updates for Week 46, ending November 15, 2025

For Everyone
NOV. 21, 2025

For Everyone
NOV. 21, 2025

KEY POINTS

Note: Due to the Thanksgiving Holiday, FluView for Week 47 will be posted on December 1, 2025.
Seasonal influenza activity remains low nationally but is increasing.

Summary

Viruses
Clinical Lab 2.9% (Trend )
positive for influenza
this week. Public Health Lab The most frequently reported
influenza viruses this week were influenza
A(H3N2).

Illness
Outpatient Respiratory Illness 2.2% (Trend )
of visits to a health care provider this week
were for respiratory illness
(below baseline).

Activity Map 2 moderate jurisdictions 0 high or very high jurisdictions

FluSurv-NET 1.7 per 100,000
cumulative hospitalization rate
per 100,000 population

NHSN LTCF Respiratory Data 0.7 per 100,000 (Trend ) weekly hospitalization rate per 100,000 residents

NHSN Hospital Respiratory Data 2,350 (Trend )
patients admitted to hospitals with influenza this week.
NCHS Mortality Unavailable this week

Pediatric Deaths 0 influenza-associated deaths
this season.
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 methodspage.¹

Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive. Key Points

Seasonal influenza activity remains low nationally but is increasing, primarily among children.
- Percent positivity for influenza and the percentage of emergency department visits for influenza among pediatric age groups increased this week.
- The timing of the increasing activity is similar to several past seasons, including the 2024-2025 season.
During Week 46, of the 203 influenza viruses reported by public health laboratories, 191 were influenza A and 12 were influenza B. Of the 160 influenza A viruses subtyped during Week 46, 43 (26.9%) were influenza A(H1N1)pdm09, 115 (71.9%) were A(H3N2), and 2 (1.2%) were A(H5). The two A(H5) specimens were from the same person.
One confirmed case of avian influenza A(H5N5) virus infection was reported to CDC this week. This is the first human case of A(H5) infection reported in the U.S. since February 2025. To date, human-to-human transmission of avian influenza A(H5) virus (H5 bird flu) has not been identified in the United States.
One human infection with an influenza A(H1N2) variant (A(H1N2)v) virus was reported to CDC this week.
No influenza-associated pediatric deaths occurring during the 2025-2026 season have been reported to CDC.
CDC estimates that there have been at least 650,000 illnesses, 7,400 hospitalizations, and 300 deaths from flu so far this season.
CDC recommends that everyone ages 6 months and older get an annual influenza (flu) vaccine, anytime viruses are circulating.¹More than 121 million doses of influenza vaccine have been distributed in the United States this season.
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.²
Influenza viruses are among several viruses contributing to respiratory disease activity. CDC has provided updated, integrated informationabout COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.

U.S. virologic surveillance

Nationally and in HHS regions 1, 2, 4, 5, 6, 8, and 10, 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. In regions 3, 7, and 9, the percentage remained stable compared to the previous week but is trending upwards over the past several weeks. Percent positivity varied by region, ranging from 1.3% (Region 7) to 10.3% (Region 8). The Region 8 data are being driven by a pediatric hospital. 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.

Clinical Laboratories
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.

-snip-

Novel Influenza A Virus Infections

Two confirmed human infections with novel influenza A viruses were reported to CDC this week. One infection with an influenza A(H5N5) virus was reported by the Washington State Department of Health and one infection with an influenza A(H1N2) variant (A(H1N2)v) virus was reported by the Vermont Department of Health.

One infection with an influenza A(H5N5) virus was reported by the Washington State Department of Public Health. The case occurred in an individual aged ≥18 years. This individual developed symptoms during the week ending October 25, 2025 (Week 43) and was hospitalized with their illness during the week ending November 8, 2025 (Week 45). Respiratory specimens collected at the healthcare facility tested positive for influenza A and were presumptive positive for influenza A(H5) at the University of Washington. The specimens were sent to the Washington State Public Health Laboratory where influenza A(H5) was confirmed using the CDC influenza A(H5) assay. Sequencing conducted at the University of Washington and at the CDC indicated this was an influenza A(H5N5) virus.The investigation by public health officials identified that the patient kept backyard poultry that had exposure to wild birds. The patient remains hospitalized. This is the twelfth confirmed influenza A(H5) case in Washington overall. Prior confirmed cases in Washington were associated with commercial poultry exposure. This is the 71^st confirmed human case of A(H5) in the United States since early 2024 and the first human case reported in the United States since February 2025.

One infection with an influenza A(H1N2)v virus was reported by the Vermont Department of Health in an individual aged ≥18 years. The individual developed symptoms and sought healthcare during the week ending October 4, 2025 (Week 40), was hospitalized but discharged on the same day, and has recovered from their illness. The investigation conducted by state public health officials was unable to determine whether the individual had exposure to swine or other animals, or whether the patient's close contacts exhibited any illness. No human-to-human transmission has been identified associated with this case.

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 person to person.

Notification to WHO of the influenza A(H5) case was completed according to International Health Regulations (IHR). For the A(H1N2)v, this is the second of this subtype reported this calendar year. More information regarding IHR can be found at http://www.who.int/topics/internatio...egulations/en/.

The CSTE position statement, which includes updated case definitions for confirmed, probable, and suspected cases is available at http://www.cste.org/resource/resmgr/...nfluenza_A.pdf.

An up-to-date human case summary during the current outbreak by state and exposure source is available at www.cdc.gov/bird-flu/situation-summary/index.html.

Information about avian influenza is available at https://www.cdc.gov/flu/avianflu/index.htm. A(H5N1) virus interim recommendations for Prevention, Monitoring, and Public Health Investigations are available at https://www.cdc.gov/bird-flu/prevent...endations.html. Additional information regarding human infections with novel influenza A viruses:

Surveillance Methods | FluView Interactive
Influenza Virus Characterization

CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories according to the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are relative to the reference viruses representing the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the polymerase acidic protein (PA) endonuclease inhibitor baloxavir. The HA clade and subclades were assigned using Nextclade (https://clades.nextstrain.org).

CDC has genetically characterized 558 influenza viruses collected since May 18, 2025.

A/H1	293
		5a.2a	7 (2.4%)	C.1.9.3	7 (2.4%)
5a.2a.1	286 (97.6%)	D.1	2 (0.7%)
D.3.1	284 (96.9%)
A/H3	146
		2a.3a.1	146 (100%)	J.2	15 (10.3%)
J.2.2	9 (6.2%)
J.2.3	19 (13.0%)
J.2.4	21 (14.4%)
K	82 (56.2%)
B/Victoria	119
		3a.2	119 (100%)	C.3.1	30 (25.2%)
C.3.2	5 (4.2%)
C.5	3 (2.5%)
C.5.1	29 (24.4%)
C.5.6	23 (19.3%)
C.5.6.1	3 (2.5%)
C.5.7	26 (21.8%)
B/Yamagata	0
		Y3	0	Y3	0

CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) assay (H1N1pdm09, H3N2, and B/Victoria viruses) or neutralization-based HINT (H3N2 viruses) using antisera from ferrets infected with reference viruses representing the recommended cell-based or recombinant influenza vaccines for the 2025-2026 Northern Hemisphere season. Antigenic differences between viruses are determined by comparing how well the antibodies raised against the vaccine reference viruses recognize the circulating viruses, which were grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses are deemed antigenically similar when their HI titer differences are less than or equal to 4-fold. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. From the recent genetically characterized viruses, a subset is selected for antigenic characterization based on identified genetic changes in surface proteins. The subset tested may not be proportional to the number of such viruses circulating in the United States. Influenza A Viruses

A(H1N1)pdm09: 127 A(H1N1)pdm09 viruses were antigenically characterized by HI, and 127 (100%) were well-recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/67/2022-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines.
A(H3N2): 50 A(H3N2) viruses were antigenically characterized by HI or HINT, and 19 (38.0%) were well-recognized (reacting at titers that were within 4-fold of the homologous virus titer in HI or reacting at titers that were less than 8-fold of the homologous virus in HINT) by ferret antisera to cell-grown A/District Of Columbia/27/2023-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines.

Influenza B Viruses

B/Victoria: 78 influenza B/Victoria-lineage virus were antigenically characterized by HI, and 54 (69.2%) were well-recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Austria/1359417/2021-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines.
B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

Assessment of Virus Susceptibility to Antiviral Medications

CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

Viruses collected in the United States since May 18, 2025, were tested for antiviral susceptibility are as follows:

Neuraminidase Inhibitors	Oseltamivir	Viruses Tested	549	291	141	117
Reduced Inhibition	1 (0.2%)	1 (0.3%)	0	0
Highly Reduced Inhibition	0	0	0	0
Peramivir	Viruses Tested	549	291	141	117
Reduced Inhibition	0	0	0	0
Highly Reduced Inhibition	0	0	0	0
Zanamivir	Viruses Tested	549	291	141	117
Reduced Inhibition	0	0	0	0
Highly Reduced Inhibition	0	0	0	0
PA Cap-Dependent Endonuclease Inhibitor	Baloxavir	Viruses Tested	528	276	138	114
Decreased Susceptibility	1 (0.2%)	1 (0.4%)	0	0

One A(H1N1)pdm09 virus had amino acid substitutions NA-I223V and NA-S247N and showed reduced inhibition by oseltamivir. One A(H1N1)pdm09 virus had PA-K34R amino acid substitution associated with reduced susceptibility to baloxavir.

High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended and data from adamantane resistance testing are not presented.

Outpatient and Emergency Department Illness Surveillance

Outpatient Respiratory Illness Visits

Continued: https://www.cdc.gov/fluview/surveill...5-week-46.html

**Commonground** · November 24, 2025, 03:43 PM

from previous post #3:

No influenza-associated pediatric deaths occurring during the 2025-2026 season have been reported to CDC.
CDC estimates that there have been at least 650,000 illnesses, 7,400 hospitalizations, and 300 deaths from flu so far this season.

**Commonground** · December 1, 2025, 04:44 PM

Weekly US Influenza Surveillance Report: Key Updates for Week 47, ending November 22, 2025

For Everyone
DEC. 1, 2025

KEY POINTS
Seasonal influenza activity remains low nationally but is increasing

Key Points

Seasonal influenza activity remains low nationally but is increasing, primarily among children and young adults.
- Percent positivity for influenza and the percentage of outpatient visits for respiratory illness and emergency department visits for influenza among pediatric age groups increased this week.
- The timing of the increasing activity is similar to several past seasons.

During Week 47, of the 358 influenza viruses reported by public health laboratories, 343 were influenza A and 15 were influenza B. Of the 305 influenza A viruses subtyped during Week 47, 54 (17.7%) were influenza A(H1N1)pdm09, 251 (82.3%) were A(H3N2), and 0 were A(H5).
No new influenza A(H5) cases were reported to CDC this week. However, one influenza A(H5N5)-associated death in the United States was reported by the Washington Department of Health in a case that was reported in mid-November. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States.

No influenza-associated pediatric deaths occurring during the 2025-2026 season have been reported to CDC.
CDC estimates that there have been at least 1,100,000 illnesses, 11,000 hospitalizations, and 450 deaths from flu so far this season.

CDC recommends that everyone ages 6 months and older get an annual influenza (flu) vaccine, anytime viruses are circulating.¹More than 124 million doses of influenza vaccine have been distributed in the United States this season.

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.²

Influenza viruses are among several viruses contributing to respiratory disease activity. CDC has provided updated, integrated informationabout COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.

-snip-

Novel Influenza A Virus Infections

The Washington Department of Health has reported that the adult patient, aged ≥ 18 years, who had been hospitalized with influenza A(H5N5) virus infection in Washington has died. This is the second person in the United States who has died as a result of an influenza A(H5) virus infection, and this is the first person with an influenza A(H5N5) virus infection. Additional information is available here: https://doh.wa.gov/newsroom/grays-ha...vian-influenza.

No new confirmed human infections with avian influenza A(H5) virus were reported to CDC this week. To date, person-to-person transmission of avian influenza A(H5) virus (H5 bird flu) has not been identified in the United States.

continued: https://www.cdc.gov/fluview/surveill...5-week-47.html

**Commonground** · December 2, 2025, 10:10 AM

CDC: Current Epidemic Trends (Based on R_t) for States [ FORECAST OUTBREAK ANALYTICS]

Epidemic trends

We estimate the time-varying reproductive number, R_t, a measure of transmission based on data from incident emergency department (ED) visits. The method for determining epidemic status estimates the probability that R_t is greater than 1 (map below). Estimated R_t values above 1 indicate epidemic growth.

The second figure below shows the estimated R_t and uncertainty interval from October 1, 2025 through November 25, 2025 for the U.S. and for each reported state. (Click on the map to view the data for a specific state). While R_t tells us if the number of infections is likely growing or declining, it does not reflect the burden of disease.

R_tshould be used alongside other surveillance metrics (such as the percentage of ED visits, which are displayed in the callout boxes in the map) for a more complete picture. View a summary of key data for COVID-19, influenza, and RSV.

Epidemic trend summary

Keep in mind

12/01/25: Current estimates may be impacted by holiday reporting effects and should be interpreted with greater uncertainty.

Interpreting Rt
What Rt can and cannot tell us
What Rt can tell us: Rt can tell us whether a current epidemic trend is growing, declining, or not changing, and is an additional tool to help public health practitioners prepare and respond.

Continued: https://www.cdc.gov/cfa-modeling-and...tes/index.html

What Rt cannot tell us: Rt cannot tell us about the underlying burden of disease, just the trend of transmission. An Rt < 1 does not mean that transmission is low, just that infections are declining. It is useful to look at respiratory disease activity in conjunction with Rt.

**Commonground** · December 7, 2025, 01:18 PM

Respiratory Virus Activity Levels
Excerpt:

Epidemic Trends
Data last updated on December 3, 2025 and presented through December 2, 2025.
View this dataset on data.cdc.gov.

Respiratory Virus Activity Levels

https://www.cdc.gov/respiratory-viruses/data/activity-levels.html

Updates on how COVID-19, Flu, and RSV may be spreading nationally and in your state

**Commonground** · December 12, 2025, 04:00 PM

Respiratory Virus Activity Levels
For Everyone
DEC. 12, 2025

This Week’s Activity Update:

Reported on Friday, December 12, 2025

The amount of acute respiratory illness causing people to seek health care is low.
RSV activity in many Southeastern, Southern, and mid-Atlantic states is increasing.
Nationally, COVID-19 activity is low.
Seasonal influenza activity continues to increase in most areas of the country.
Nationally, wastewater activity level for COVID-19 and flu is low and RSV is very low.

Epidemic Trends
CDC uses data from emergency department visits to model epidemic trends. This model helps tell whether the number of new respiratory infections is growing or declining in your state. While this model tells us the trend, it does not tell us the actual number of current infections with SARS-CoV-2 (the virus that causes COVID-19), influenza virus, or RSV. Refer to data notesfor more details.

Influenza:

https://www.cdc.gov/respiratory-viru...n_7-data-notes

**Commonground** · December 13, 2025, 10:44 AM

Weekly US Influenza Surveillance Report: Key Updates for Week 49, ending December 6, 2025
Excerpts:

Key Points

Seasonal influenza activity continues to increase in most areas of the country. Some indicators are elevated but severity indicators remain low and flu season is just starting.
Nationally, the percentage of respiratory specimens testing positive for influenza, and indicators of influenza associated outpatient/emergency department visits, hospitalizations and deaths increased this week compared to last. The timing of this increasing activity is similar to several past seasons.
The first influenza-associated pediatric death occurring during the 2025-2026 season was reported by CDC this week.
Influenza A(H3N2) viruses are the most frequently reported influenza viruses so far this season.

During Week 49, of the 547 influenza viruses reported by public health laboratories, 525 were influenza A and 22 were influenza B. Of the 401 influenza A viruses subtyped during Week 49, 56 (14.0%) were influenza A(H1N1)pdm09, and 345 (86.0%) were A(H3N2).

A new influenza A(H3N2) virus subclade J.2.4.1, also recently renamed "H3N2 subclade K," was identified by CDC in August 2025. These viruses have small changes in their hemagglutinin gene and have been antigenically characterized as "antigenically drifted" in comparison to the virus selected as the A(H3N2) component of the U.S. 2025-26 seasonal influenza vaccinesAmong 163 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 89.0% belonged to subclade K.
When circulating influenza viruses are drifted from viruses represented in the influenza vaccines, vaccine effectiveness may be reduced but influenza vaccination continues to provide benefits, including: 1) protection against severe influenza illness, hospitalization, and death; 2) protection against other circulating influenza viruses represented in the influenza vaccines; and 3) help to reduce the overall community spread of influenza.
Early estimates of 2025-26 influenza vaccine effectiveness in England against influenza-associated hospitalization remained within expected ranges of 70-75% for children and 30-40% for adults, suggesting that influenza vaccination remains an effective tool in preventing influenza-related hospitalizations this season.
Influenza vaccine effectiveness networks are collecting real-world data to produce early estimates of influenza vaccine effectiveness in the United States once influenza activity has increased and sufficient data have been collected to conduct these analyses.
CDC estimates that there have been at least 2,900,000 illnesses, 30,000 hospitalizations, and 1,200 deaths from flu so far this season.
CDC recommends that everyone 6 months and older who has not yet been vaccinated this season get an annual influenza (flu) vaccine.¹More than 127 million doses of influenza vaccine have been distributed in the United States this season.
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 of developing serious flu-related complications.²
Influenza viruses are among several viruses contributing to respiratory disease activity. CDC has provided updated, integrated informationabout COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.
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.

Weekly US Influenza Surveillance Report: Key Updates for Week 49, ending December 6, 2025

https://www.cdc.gov/fluview/surveillance/2025-week-49.html

Nationally, seasonal influenza activity continues to increase

**Commonground** · December 19, 2025, 06:46 PM

Respiratory Virus Activity Levels

For Everyone
DEC. 19, 2025
Summary

This Week’s Activity Update:

Reported on Friday, December 19, 2025

The amount of acute respiratory illness causing people to seek health care is low.
RSV activity in many Southeastern, Southern, and mid-Atlantic states is increasing.
Nationally, COVID-19 activity is low.
Seasonal influenza activity continues to increase across the country.
Nationally, wastewater activity level for COVID-19 and flu is low and RSV is very low.

Continued: https://www.cdc.gov/respiratory-viru...ty-levels.html

**sharon sanders** · December 20, 2025, 08:49 AM

Weekly US Influenza Surveillance Report: Key Updates for Week 50, ending December 13, 2025

For Everyone
Dec. 19, 2025

Key points

Note: Due to the Christmas Holiday, FluView for Week 51 will be posted on December 30, 2025.
Seasonal influenza activity continues to increase across the country.

Summary

Viruses

Clinical Lab 14.8% (Trend )
positive for influenza
this week. Public Health Lab The most frequently reported
influenza viruses this week were influenza
A(H3N2).

Illness

Outpatient Respiratory Illness 4.1% (Trend )
of visits to a health care provider this week
were for respiratory illness
(above baseline). Activity Map 8 moderate jurisdictions 17 high or very high jurisdictions FluSurv-NET 11.0
cumulative hospitalization rate
per 100,000 population NHSN LTCF Respiratory
Data 14.3 (Trend ) weekly hospitalization rate
per 100,000 residents NHSN Hospital Respiratory Data 9,944 (Trend )
patients admitted to hospitals
with influenza this week. NCHS Mortality 0.3% (Trend ) of deaths attributed to influenza this week. Pediatric Deaths 2 influenza-associated deaths occuring during the 2025-26 season were reported this week.
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.

Key Points

Seasonal influenza activity continues to increase across the country. The timing of this increasing activity is similar to several past seasons.
Sustained elevated activity is observed across multiple key activity indicators in many areas of the country, signaling the start of the 2025-2026 influenza season. Severity indicators remain low at this time, but influenza activity is expected to continue for weeks.
Two influenza-associated pediatric deaths were reported to CDC this week, bringing the 2025-2026 season total to three reported flu-related pediatric deaths.
Influenza A(H3N2) viruses are the most frequently reported influenza viruses so far this season.

During Week 50, of the 927 influenza viruses reported by public health laboratories, 911 were influenza A and 16 were influenza B. Of the 706 influenza A viruses subtyped during Week 50, 71 (10.1%) were influenza A(H1N1)pdm09 and 635 (89.9%) were A(H3N2).

- Among 216 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 89.8% belonged to subclade K.

CDC estimates that there have been at least 4,600,000 illnesses, 49,000 hospitalizations, and 1,900 deaths from flu so far this season.

CDC recommends that everyone 6 months and older who has not yet been vaccinated this season get an annual influenza (flu) vaccine.¹Approximately 130 million doses of influenza vaccine have been distributed in the United States this season.
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.²
Influenza viruses are among several viruses contributing to respiratory disease activity. CDC provides updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.
No new avian influenza A(H5) infections were reported to CDC this week. To date, person-to-person transmission of influenza A(H5) viruses has not been identified in the United States.

U.S. virologic surveillance

Nationally and in HHS regions 1, 2, 3, 4, 5, 6, 7, 8 and 9, the percentage of respiratory specimens testing positive for influenza virus in clinical laboratories increased (change of at least 0.5 percentage points). In Region 10, the percentage has declined slightly compared to the previous week, but this could be due to limited data reporting. Region 8 had the highest percent positivity (27.2%) and Region 10 had the lowest (6.4%). Influenza A(H3N2) viruses were the most frequently reported influenza viruses this week; however, the distribution of circulating viruses varies by region. 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.

Clinical Laboratories

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.

No. of specimens tested	70,675	666,065
No. of positive specimens (%)	10,456 (14.8%)	29,649 (4.5%)
*Positive specimens by type*
Influenza A	9,980 (95.4%)	27,861 (94.0%)
Influenza B	476 (4.6%)	1,788 (6.0%)

Public Health Laboratories

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.

No. of specimens tested	1,414	15,040
No. of positive specimens	927	6,668
*Positive specimens by type/subtype*
Influenza A	911 (98.3%)	6,399 (96.0%)
Subtyping Performed	706 (77.5%)	5,934 (92.7%)
(H1N1)pdm09	71 (10.1%)	1,093 (18.4%)
H3N2	635 (89.9%)	4,839 (81.5%)
H3N2v^†	0	0
H5*	0	2 (0.0%)
Subtyping not performed	205 (22.5%)	465 (7.3%)
Influenza B	16 (1.7%)	269 (4.0%)
Lineage testing performed	6 (37.5%)	71 (26.4%)
Yamagata lineage	0	0
Victoria lineage	6 (100%)	71 (100%)
Lineage not performed	10 (62.5%)	198 (73.6%)

_{*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. 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 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 tested only at CDC and could include more than one specimen tested per person. Specimens tested as part of routine influenza surveillance as well as those tested as part of targeted testing for people exposed to avian influenza A(H5) are included.}

Additional virologic surveillance information for current and past seasons:

Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data

Novel Influenza A Virus Infections

No new confirmed human infections with avian influenza A(H5) virus were reported to CDC this week. To date, person-to-person transmission of avian influenza A(H5) virus (H5 bird flu) has not been identified in the United States.

The CSTE position statement, which includes updated case definitions for confirmed, probable, and suspected cases is available at http://www.cste.org/resource/resmgr/...nfluenza_A.pdf.

An up-to-date human case summary during the current outbreak by state and exposure source is available at www.cdc.gov/bird-flu/situation-summary/index.html.

Information about avian influenza is available at https://www.cdc.gov/flu/avianflu/index.htm. A(H5N1) virus interim recommendations for Prevention, Monitoring, and Public Health Investigations are available at https://www.cdc.gov/bird-flu/prevent...endations.html.

Additional information regarding human infections with novel influenza A viruses:

Surveillance Methods | FluView Interactive

Influenza Virus Characterization

CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories according to the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are relative to the reference viruses representing the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the polymerase acidic protein (PA) endonuclease inhibitor baloxavir. The HA clade and subclades were assigned using Nextclade (https://clades.nextstrain.org).

CDC has genetically characterized 363 influenza viruses collected since September 28, 2025.

A/H1	116
		5a.2a	2 (1.7%)	C.1.9.3	2 (1.7%)
5a.2a.1	114 (98.3%)	D.3.1	65 (56.0%)
D.3.1.1	49 (42.2%)
A/H3	216
		2a.3a.1	216 (100%)	J.2	2 (0.9%)
J.2.2	4 (1.9%)
J.2.3	10 (4.6%)
J.2.4	6 (2.8%)
K	194 (89.8%)
B/Victoria	31
		3a.2	31 (100%)	C.3.1	12 (38.7%)
C.5.1	7 (22.6%)
C.5.6	7 (22.6%)
C.5.6.1	3 (9.7%)
C.5.7	2 (6.5%)
B/Yamagata	0
		Y3	0	Y3	0

CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) assay (H1N1pdm09, H3N2, and B/Victoria viruses) or neutralization-based HINT (H3N2 viruses) using antisera from ferrets infected with reference viruses representing the recommended cell-based or recombinant influenza vaccines for the 2025-2026 Northern Hemisphere season. Antigenic differences between viruses are determined by comparing how well the antibodies raised against the vaccine reference viruses recognize the circulating viruses, which were grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses are deemed antigenically similar when their HI titer differences are less than or equal to 4-fold. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. Circulating viruses with antigenic testing results that show titer differences greater than 4-fold by HI or equal to or greater than 8-fold by HINT) are considered “low reactors” or antigenically drifted compared to the vaccine virus. From the recent genetically characterized viruses, a subset is selected for antigenic characterization based on identified genetic changes in their surface proteins. The subset tested may not be proportional to the number of such viruses circulating in the United States.

Influenza A Viruses

A(H1N1)pdm09: 23 A(H1N1)pdm09 viruses collected since September 28, 2025, were antigenically characterized by HI, and 23 (100%) were well-recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/67/2022-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines.
A(H3N2): 35 A(H3N2) viruses collected since September 28, 2025, were antigenically characterized by HI or HINT, and 3 (9.0%) were well-recognized (reacting at titers that were within 4-fold of the homologous virus titer in HI or reacting at titers that were less than 8-fold of the homologous virus in HINT) by ferret antisera to cell-grown A/District Of Columbia/27/2023-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines.

Influenza B Viruses

B/Victoria: 12 influenza B/Victoria-lineage viruses collected since September 28, 2025, since were antigenically characterized by HI, and 8 (67.0%) were well-recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Austria/1359417/2021-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines.
B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

Assessment of Virus Susceptibility to Antiviral Medications

CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

Viruses collected in the U.S. since September 28, 2025, were tested for antiviral susceptibility as follows:

Neuraminidase Inhibitors	Oseltamivir	Viruses Tested	354	116	208	30
Reduced Inhibition	0	0	0	0
Highly Reduced Inhibition	0	0	0	0
Peramivir	Viruses Tested	354	116	208	30
Reduced Inhibition	0	0	0	0
Highly Reduced Inhibition	0	0	0	0
Zanamivir	Viruses Tested	354	116	208	30
Reduced Inhibition	0	0	0	0
Highly Reduced Inhibition	0	0	0	0
PA Cap-Dependent Endonuclease Inhibitor	Baloxavir	Viruses Tested	341	107	204	30
Decreased Susceptibility	0	0	0	0

High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended and data from adamantane resistance testing are not presented.

Outpatient and Emergency Department Illness Surveillance

Outpatient Respiratory Illness Visits

The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for respiratory illness referred to as influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza virus, SARS-CoV-2, and RSV. It is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity.

Nationally, during Week 50, 4.1% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. This week’s percentage increased (change of > 0.1 percentage points) compared to Week 49 and is above the national baseline of 3.1% for the second consecutive week. The percentage of visits for ILI increased in all HHS ten Regions this week compared to last. Region 9 is at its regional baseline, while all other regions (1, 2, 3, 4, 5, 6, 7, 8, and 10) are above their respective baselines in Week 50. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.

Outpatient Respiratory Illness Visits by Age Group

About 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Based on these data, the percentage of visits for respiratory illness remained stable (change of ≤ 0.1 percentage points) in the 50-64 years age group and increased (change of > 0.1 percentage points) in all other age groups (0-4 years, 5-24 years, 25-49 years, and 65 years and older) in Week 50 compared to Week 49.

Outpatient Respiratory Illness Activity Map

Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).

Week 50 (Week ending Dec. 13, 2025)	Week 49 (Week ending Dec. 6, 2025)	Week 50 (Week ending Dec. 13, 2025)	Week 49 (Week ending Dec. 6, 2025)
Very High	6	1	17	4
High	11	5	62	32
Moderate	8	7	85	52
Low	14	16	166	134
Minimal	15	26	382	490
Insufficient Data	1	0	217	217

_{*Data collected in ILINet may disproportionally represent certain populations within a jurisdiction or CBSA, and therefore, may not accurately depict the full picture of influenza activity for the entire jurisdiction or CBSA. Differences in the data presented here by CDC and independently by some health departments likely represent differing levels of data completeness with data presented by the health department likely being the more complete.}

Additional information about medically attended visits for ILI for current and past seasons:

Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map

National Syndromic Surveillance System (NSSP)

The national percentage of emergency department (ED) visits with a discharge diagnosis (DD) of influenza reported in NSSP was 2.8% during Week 50 and increased (change of > 0.1 percentage point) compared to the previous week. The percentage of ED visits with a DD of influenza increased this week compared to the previous week among all age groups (0-4 years, 5-17 years, 18-64 years, and 65 years and older) and in all ten HHS regions. RegionNationalRegion 1Region 2Region 3Region 4Region 5Region 6Region 7Region 8Region 9Region 10
Season
2025-2026x
2024-2025x

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2.0%4.0%6.0%8.0%10.0%12.0%14.0%16.0%Percent of Emergency Department Visits for InfluenzaWeek 42 of 2024Week 46 of 2024Week 50 of 2024Week 2 of 2025Week 6 of 2025Week 10 of 2025Week 14 of 2025Week 18 of 2025Week 22 of 2025Week 26 of 2025Week 30 of 2025Week 34 of 2025Week 38 of 2025Week 42 of 2025Week 46 of 2025Week 50 of 2025

Age Group

Skip Data Table
Data Table Download Data (CSV)
Skipped data table.

Additional information about emergency department visits for flu for current and past seasons:‎‎‎

Surveillance Methods | Emergency Department Visits for COVID-19, flu, and RSV

Hospitalization surveillance

FluSurv-Net

Influenza-Associated Hospitalizations: The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 10% of the U.S. population. FluSurv-NET hospitalization data are preliminary. As data are received each week, prior case counts and rates are updated accordingly.

A total of 3,833 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2025, and December 13, 2025. The weekly hospitalization rate observed during Week 50 was 3.5 per 100,000 population, which increased from a rate of 2.7 per 100,000 population last week. The cumulative hospitalization rate observed in Week 50 was 11 per 100,000 population. This is the third highest cumulative rate at week 50 since the 2010-11 season following the 2022-23 and 2023-24 seasons, with rates of 42.4 and 13.6 respectively.

Among all hospitalizations, 3,646 (95.1%) were associated with influenza A virus, 155 (4%) with influenza B virus, 5 (0.1%) with influenza A virus and influenza B virus co-infection, and 27 (0.7%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 634 (85.2%) were A(H3N2), and 110 (14.8%) were A(H1N1)pdm09.

When examining rates by age, the highest rate of hospitalization per 100,000 population was among adults aged 65 and older (31.4), followed by children aged 0-4 years (14.4), adults aged 50-64 years (9.9), children aged 5-17 years (7.3), and adults aged 18-49 years (4.8).

When examining age-adjusted rates by race and ethnicity, the highest rate of hospitalization per 100,000 population was among non-Hispanic Black persons (21.1), followed by American Indian or Alaska Native persons (13.4), Hispanic persons (10.9), non-Hispanic White persons (8.7), and Asian and/or Pacific Islander persons (5.1).

_{**In this figure, weekly rates for all seasons prior to the 2025-26 season reflect end-of-season rates. For the 2025-26 season, rates for recent hospital admissions are subject to reporting delays and are shown as a dashed line for the current season. As hospitalization data are received each week, prior case counts and rates are updated accordingly.}

Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:

Surveillance Methods | FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics | RESP-NET Interactive

National Healthcare Safety Network (NHSN) Hospital Respiratory Data

Hospitals report to NHSN the weekly number of patients with laboratory-confirmed influenza who were admitted to the hospital. Nationally, during Week 50, 9,944 laboratory-confirmed influenza-associated hospitalizations were reported. This week's influenza-associated hospital admission rate (2.9 per 100,000 population) increased (difference of ≥ 0.2) compared to Week 49.

Laboratory confirmed influenza-associated hospital admission rates per 100,000 population increased in HHS regions 1 – 9. Region 10 decreased slightly but this could be due to limited data reporting. Admission rates ranged from 0.8 (Region 10) to 6.9 (Region 2) during Week 50.

When examining rates by age for Week 50, the hospitalization rate among all age groups increased (difference of ≥ 0.2). The highest hospital admission rate per 100,000 population was among those 65 years and older (8.5), followed by children aged 0-4 years (3.7), and adults aged 50-64 years age groups (2.4).

Additional NHSN Hospital Respiratory Data information:

Surveillance Methods | Additional Data | FluView Interactive

National Healthcare Safety Network (NHSN) Long-Term Care Respiratory Pathogens & Vaccination Module

Long-term care facilities (LTCFs [e.g., Nursing homes/skilled nursing facilities]) report respiratory pathogen (e.g., COVID-19, influenza and RSV) data, including vaccination, cases, and hospitalizations among residents, to the NHSN Long-Term Care Respiratory Pathogens & Vaccination Module.

Nationally, during Week 50, the hospitalization rate for residents with a positive influenza test in the prior 10 days was 14.3 per 100,000 residents. The national rate and the rate in HHS Regions 1-9 have been increasing over the past several weeks. In Region 10, the rate remains low and does not show a consistent trend. View Larger Download National Healthcare Safety Network (NHSN) Long-Term Care Respiratory Pathogens & Vaccination Module
Mortality surveillance

National Center for Health Statistics (NCHS) Mortality Surveillance

Based on NCHS mortality surveillance data available on December 18, 2025, 0.3% of the deaths that occurred during the week ending December 13, 2025 (Week 50), were due to influenza. This percentage increased (≥ 0.1 percentage point change) compared to Week 49. The data presented are preliminary and may change as more data are received and processed.

Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:

Surveillance Methods | FluView Interactive

Influenza-Associated Pediatric Mortality

Two influenza-associated pediatric deaths occurring during the 2025-2026 season were reported to CDC during Week 50. One death occurred during Week 47 (the week ending November 22, 2025) and the other one occurred during Week 50 (the week ending December 13, 2025). Both deaths were associated with influenza A(H3) viruses.

A total of three influenza-associated pediatric deaths occurring during the 2025-2026 season have been reported to CDC.

Additional pediatric mortality surveillance information for current and past seasons:

Surveillance Methods | FluView Interactive
All data in this report are preliminary and may change as more reports are received.

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.

Additional National and International Influenza Surveillance Information

Indicators Status by System

Increasing:
Decreasing:
Stable:

Clinical Labs: Up or down arrows indicate a change of greater than or equal to 0.5 percentage points in the percent of specimens positive for influenza compared to the previous week.
Outpatient Respiratory Illness (ILINet): Up or down arrows indicate a change of greater than 0.1 percentage points in the percent of visits due to respiratory illness (ILI) compared to the previous week.
NHSN Hospitalizations: Up or down arrows indicate change of greater than or equal to 0.2 in the rate of hospital admissions or greater than or equal to 691 patients admitted with laboratory-confirmed influenza compared to the previous week.
NHSN Long- Term Care (LTC): Up or down arrows indicate change of greater than or equal to 5% in hospitalization rates for residents in LTC facilities who were hospitalized with laboratory-confirmed influenza compared to the previous week.
NCHS Mortality: Up or down arrows indicate change of greater than 0.1 percentage points of the percent of deaths due to influenza compared to the previous week.

Additional surveillance information

FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Puerto Rico	Virgin Islands

Public Health Agency of Canada:
The most up-to-date influenza information from Canada is available in Canada's weekly FluWatch report.

Public Health England:
The most up-to-date influenza information from the United Kingdom is available from Public Health England.

Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.

A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

Weekly US Influenza Surveillance Report: Key Updates for Week 50, ending December 13, 2025

https://www.cdc.gov/fluview/surveillance/2025-week-50.html

Nationally, seasonal influenza activity continues to increase

**Commonground** · December 31, 2025, 06:43 AM

Weekly US Influenza Surveillance Report: Key Updates for Week 51, ending December 20, 2025

DEC. 30, 2025 KEY POINTS

Please note: Week 52 FluView will be posted on Monday January 5 due to the New Year holiday.
Seasonal influenza activity is elevated and continues to increase across the country.

Summary

Viruses

Clinical Lab 25.6% (Trend )
positive for influenza
this week. Public Health Lab The most frequently reported
influenza viruses this week were influenza
A(H3N2). Illness

Outpatient Respiratory Illness 6.0% (Trend )
of visits to a health care provider this week
were for respiratory illness
(above baseline). Activity Map 8 moderate jurisdictions 32 high or very high jurisdictions

FluSurv-NET 18.2 per 100,000
cumulative hospitalization rate
per 100,000 population

NHSN LTCF Respiratory Data 22.9 per 100,000 (Trend ) weekly hospitalization rate per 100,000 residents
NHSN Hospital Respiratory Data 19,053 (Trend ) patients admitted to hospitals with influenza this week.
NCHS Mortality 0.5% (Trend ) of deaths attributed to influenza this week. Pediatric Deaths 5 influenza-associated deaths occuring during the 2025-26 season were reported this week.

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 methodspage.¹
Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

Key Points

Seasonal influenza activity is elevated and continues to increase across the country.
Sustained elevated activity is observed across multiple key activity indicators in all areas of the country. Severity indicators remain low at this time, but influenza activity is expected to continue for several weeks.
Five influenza-associated pediatric deaths were reported to CDC this week, bringing the 2025-2026 season total to eight reported flu-related pediatric deaths.
Influenza A(H3N2) viruses are the most frequently reported influenza viruses so far this season.
During Week 51, of the 2,086 influenza viruses reported by public health laboratories, 2,029 were influenza A and 57 were influenza B. Of the 1,627 influenza A viruses subtyped during Week 51, 134 (8.2%) were influenza A(H1N1)pdm09 and 1,493 (91.8%) were A(H3N2).
- Among 275 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 89.5% belonged to subclade K.
CDC estimates that there have been at least 7,500,000 illnesses, 81,000 hospitalizations, and 3,100 deaths from flu so far this season.
CDC recommends that everyone 6 months and older who has not yet been vaccinated this season get an annual influenza (flu) vaccine.¹Approximately 130 million doses of influenza vaccine have been distributed in the United States this season.
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.²
Influenza viruses are among several viruses contributing to respiratory disease activity. CDC provides updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.
No new avian influenza A(H5) infections were reported to CDC this week. To date, person-to-person transmission of influenza A(H5) viruses has not been identified in the United States.

U.S. virologic surveillance

Nationally and in all ten HHS regions the percentage of respiratory specimens testing positive for influenza virus in clinical laboratories increased (change of at least 0.5 percentage points) in Week 51 compared to Week 50. Region 8 had the highest percent positivity (34.9%) and Region 9 had the lowest (10.8%). Influenza A(H3N2) viruses were the most frequently reported influenza viruses this week; however, the distribution of circulating viruses varies by region. 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.

continued: https://www.cdc.gov/fluview/surveill...5-week-51.html

**Commonground** · January 5, 2026, 02:46 PM

Weekly US Influenza Surveillance Report: Key Updates for Week 52, ending December 27, 2025
JAN. 5, 2026

KEY POINTS
Seasonal influenza activity is elevated and continues to increase across the country

.

Key Points

Seasonal influenza activity is elevated and continues to increase across the country.
Sustained elevated influenza activity is observed across multiple key surveillance indicators in all areas of the country. As of Week 52, CDC's in-season severity assessment framework classified the season as a moderately severe season for the first time. (https://www.cdc.gov/flu/php/surveillance/index.html)
Activity is expected to continue for several weeks.
One influenza-associated pediatric death occurring in the 2025-2026 season was reported to CDC this week, bringing the season total to nine reported influenza-related pediatric deaths.
Influenza A(H3N2) viruses are the most frequently reported influenza viruses so far this season.
During Week 52, of the 994 influenza viruses reported by public health laboratories, 971 were influenza A and 23 were influenza B. Of the 600 influenza A viruses subtyped during Week 52, 53 (8.8%) were influenza A(H1N1)pdm09 and 547 (91.2%) were A(H3N2).
- Among 389 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 90.5% belonged to subclade K.
CDC estimates that there have been at least 11,000,000 illnesses, 120,000 hospitalizations, and 5,000 deaths from flu so far this season.
CDC recommends that everyone 6 months and older who has not yet been vaccinated this season get an annual influenza (flu) vaccine.¹Approximately 130 million doses of influenza vaccine have been distributed in the United States this season.
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.²
Influenza viruses are among several viruses contributing to respiratory disease activity. CDC provides updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.
No new avian influenza A(H5) infections were reported to CDC this week. To date, person-to-person transmission of influenza A(H5) viruses has not been identified in the United States.

U.S. virologic surveillance

Nationally and in all ten HHS regions the percentage of respiratory specimens testing positive for influenza virus in clinical laboratories increased (change of at least 0.5 percentage points) in Week 52 compared to Week 51. Region 8 had the highest percent positivity (45.5%) and Region 10 had the lowest (16.9%). Influenza A(H3N2) viruses were the most frequently reported influenza viruses this week; however, the distribution of circulating viruses varies by region. 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.

Clinical Laboratories

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.

Continued: https://www.cdc.gov/fluview/surveill...5-week-52.html

**Commonground** · January 9, 2026, 10:02 AM

[note date. New report due today 1/9/26]

Current Epidemic Trends (Based on R_t) for States
JAN. 5, 2026

Current Epidemic Trends (Based on Rt) for States

https://www.cdc.gov/cfa-modeling-and-forecasting/rt-estimates/index.html

CFA’s Rt page estimates COVID-19, influenza, and RSV epidemic trends for U.S. states.

**Commonground** · January 9, 2026, 12:58 PM

Weekly US Influenza Surveillance Report: Key Updates for Week 53, ending January 3, 2025
JAN. 9, 2026

Summary

Viruses

Illness

Key Points

Seasonal influenza activity remains elevated across the country.

Although some indicators have decreased or remained stable this week compared to last, this could be due to changes in healthcare seeking or reporting during the holidays rather than an indication that influenza activity has peaked. The country is still experiencing elevated influenza activity, and elevated influenza activity is expected to continue for several more weeks. CDC's in-season severity assessment framework classified the season as a moderately severe season.

Eight influenza-associated pediatric deaths occurring in the 2025-2026 season were reported to CDC this week, bringing the season total to 17 reported influenza-related pediatric deaths.
Influenza A(H3N2) viruses are the most frequently reported influenza viruses so far this season

During Week 53, of the 1,259 influenza viruses reported by public health laboratories, 1,223 were influenza A and 36 were influenza B. Of the 885 influenza A viruses subtyped during Week 53, 68 (7.7%) were influenza A(H1N1)pdm09 and 817 (92.3%) were influenza A(H3N2).
- Among 436 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 91.5% belonged to subclade K.

CDC estimates that there have been at least 15,000,000 illnesses, 180,000 hospitalizations, and 7,400 deaths from flu so far this season.
Influenza (flu) vaccination has been shown to reduce the risk of flu and its potentially serious complications. There is still time to get vaccinated against flu this season. Approximately 130 million doses of influenza vaccine have been distributed in the United States this season.
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.¹

Influenza viruses are among several viruses contributing to respiratory disease activity. CDC provides updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.

No new avian influenza A(H5) infections were reported to CDC this week. To date, person-to-person transmission of influenza A(H5) viruses has not been identified in the United States.

Continued: https://www.cdc.gov/fluview/surveill...5-week-53.html

Announcement

US FluView - Weekly Surveillance Flu report 2025/2026 season - for trend analysis

US FluView - Weekly Surveillance Flu report 2025/2026 season - for trend analysis

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