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Flu Activity Declines Across the U.S., But Experts Urge Continued Vigilance
Table of Contents
- Flu Activity Declines Across the U.S., But Experts Urge Continued Vigilance
- U.S. Virologic Surveillance: A Closer Look
- Clinical Laboratories: National Testing Summary
- Public Health Laboratories: Subtype and Lineage Tracking
- Novel Influenza A Virus Infections: Vigilance against Avian Flu
- Practical Implications for U.S. Readers
- Addressing Potential Counterarguments
- Conclusion
- CDC’s Latest flu Virus Analysis: What It Means for the U.S. This Season
- Flu Watch: Respiratory Illnesses Above Baseline,Antiviral Resistance Emerges
- Influenza Activity update: Week 12 Shows Declining Trends but High Hospitalization Rates
- National Overview
- Virologic Surveillance: Analyzing Flu Strains
- Outpatient Illness Surveillance: Tracking ILI Activity
- National Syndromic Surveillance system (NSSP)
- Hospitalization Surveillance: Monitoring severe Cases
- Mortality Surveillance: Tracking Flu-Related Deaths
- Additional National and International Influenza Surveillance Information
- Influenza Activity update: Week 12 Shows Declining Trends but high Hospitalization Rates
washington, D.C. – As spring unfolds, the Centers for Disease Control and Prevention (CDC) reports a welcome decrease in influenza activity across the nation. However, health officials are emphasizing the importance of remaining vigilant and informed about respiratory viruses, including COVID-19, influenza, and respiratory syncytial virus (RSV). The CDC provides updated facts on these viruses weekly, offering a comprehensive view of their activity.
“Staying informed is our best defence,” explains Dr. Emily Carter, a leading epidemiologist. “Even as flu cases decline, other respiratory viruses can still pose a threat, especially to vulnerable populations.”
U.S. Virologic Surveillance: A Closer Look
The CDC’s latest data reveals a promising trend: the percentage of respiratory specimens testing positive for influenza has decreased in all 10 Health and Human Services (HHS) regions. This decline, defined as a change of 0.5 percentage points or greater, signals a weakening of the flu’s grip on the country.The predominant influenza viruses circulating this season are influenza A(H1N1)pdm09 and A(H3N2).
For those seeking detailed regional and state-level data, the CDC’s FluView Interactive tool offers an in-depth look at influenza trends. This resource provides valuable insights into age group distribution and virus prevalence across different geographic areas.It’s meaningful to note that the data excludes viruses associated with recent live attenuated influenza vaccine (LAIV) administration, ensuring an accurate depiction of circulating strains.
Clinical Laboratories: National Testing Summary
Clinical laboratories across the U.S. play a crucial role in monitoring influenza activity. Their testing results provide a snapshot of the virus’s presence in communities nationwide. The CDC compiles this data to track weather influenza activity is increasing or decreasing.
| Metric | Week 12 | Cumulative Since September 29, 2024 (Week 40) |
| ————————– | ———— | ——————————————— |
| Number of Specimens Tested | 78,062 | 2,785,139 |
| Positive Specimens (%) | 8,358 (10.7%) | 447,473 (16.1%) |
| Influenza A | 4,961 (59.4%) | 415,255 (92.8%) |
| Influenza B | 3,397 (40.6%) | 32,218 (7.2%) |
These figures highlight the significant volume of testing conducted and the proportion of positive results, offering a clear picture of influenza’s prevalence.
Public Health Laboratories: Subtype and Lineage Tracking
Public health laboratories provide a deeper level of analysis, monitoring the specific subtypes and lineages of circulating influenza viruses. This information is critical for understanding the virus’s evolution and ensuring that vaccines remain effective.
| Metric | Week 12 | Cumulative As September 29, 2024 (Week 40) |
| ———————————— | ———— | ——————————————— |
| Number of specimens Tested | 2,759 | 118,723 |
| Number of Positive Specimens | 1,952 | 80,759 |
| Influenza A | 1,827 (93.6%) | 78,118 (96.7%) |
| (H1N1)pdm09 | 844 (52.2%) | 35,953 (52.3%) |
| H3N2 | 772 (47.8%) | 32,731 (47.6%) |
| Influenza B | 125 (6.4%) | 2,641 (3.3%) |
| Victoria Lineage | 62 (100.0%) | 1,228 (100.0%) |
The data reveals the dominance of influenza A, particularly the (H1N1)pdm09 and H3N2 subtypes. It also shows that among influenza B viruses, the Victoria lineage is the most prevalent.
Novel Influenza A Virus Infections: Vigilance against Avian Flu
While seasonal influenza is a recurring concern, the emergence of novel influenza A viruses, such as avian influenza (H5N1), poses a potential threat. Currently, there are no confirmed human infections with influenza A(H5) virus reported to the CDC this week.”The risk of human-to-human transmission of avian influenza remains low in the U.S.,” assures Dr. Carter. “However, we must remain vigilant and monitor the situation closely.”
The Council of State and Territorial Epidemiologists (CSTE) has developed updated case definitions for confirmed, probable, and suspected cases of novel influenza A virus infections. These definitions are crucial for accurate surveillance and rapid response.
Practical Implications for U.S. Readers
Stay Informed: Regularly check the CDC’s website for updated information on respiratory virus activity.
Practise Good Hygiene: Wash your hands frequently, cover your coughs and sneezes, and avoid touching your face.
Consider Vaccination: While flu season is waning, vaccination can still provide protection, especially for those at high risk.
Seek Medical Attention: If you experience symptoms of a respiratory illness, consult a healthcare professional.
Addressing Potential Counterarguments
Some may argue that with declining flu activity, there is no need for continued vigilance.However, experts emphasize that respiratory viruses can circulate year-round, and new variants can emerge at any time. Maintaining awareness and practicing preventive measures is essential for protecting public health.
Conclusion
While the decrease in influenza activity is encouraging, it is crucial to remain informed and proactive in preventing the spread of respiratory viruses. By staying updated on the latest data, practicing good hygiene, and seeking medical attention when necessary, we can collectively safeguard our communities.
CDC’s Latest flu Virus Analysis: What It Means for the U.S. This Season
Comprehensive report on influenza virus characterization and its implications for public health in the United States.
Published: [Current Date]
Influenza Update: CDC monitors Evolving Flu Strains
The Centers for Disease Control and Prevention (CDC) is diligently tracking the ever-changing landscape of influenza viruses circulating across the United States. This ongoing surveillance is crucial for understanding how well current flu vaccines match circulating strains and for monitoring any emerging resistance to antiviral medications. The CDC’s efforts provide vital information for healthcare professionals and the public, informing decisions about prevention and treatment.
The CDC emphasizes the importance of genetic characterization, explaining that these data “are used to compare how similar the currently circulating influenza viruses are relative to the reference viruses representing the current influenza vaccines.” This comparison is a cornerstone of public health strategy, allowing for timely adjustments to vaccine formulations if necessary.
Furthermore, the CDC actively monitors “evolutionary changes that continually occur in influenza viruses circulating in humans.” This vigilance is essential as influenza viruses are notorious for their ability to mutate rapidly, perhaps rendering existing vaccines less effective.
Beyond genetic analysis, the CDC also assesses the susceptibility of circulating viruses to antiviral drugs, including oseltamivir (Tamiflu), zanamivir (Relenza), peramivir (Rapivab), and baloxavir (Xofluza). This information is critical for guiding treatment decisions, especially for individuals at high risk of complications from the flu.
The HA clade and subclades are assigned using Nextclade, a tool accessible at https://clades.nextstrain.org.
Key Findings from Recent Virus Characterization
As of the latest report, the CDC has genetically characterized 3,067 influenza viruses collected since September 29, 2024. This substantial dataset provides a detailed snapshot of the dominant flu strains currently affecting the U.S. population.
Here’s a breakdown of the key findings:
| virus Subtype or Lineage | Genetic Characterization | ||||
|---|---|---|---|---|---|
| Total No. of Subtype/Lineage Tested |
HA Clade |
Number (% of subtype/lineage tested) |
HA Subclade |
Number (% of subtype/lineage tested) |
|
| A/H1 | 1,155 | ||||
| 5a.2a | 576 (49.9%) | C.1.9 | 75 (6.5%) | ||
| C.1.9.1 | 68 (5.9%) | ||||
| C.1.9.2 | 5 (0.4%) | ||||
| C.1.9.3 | 422 (36.5%) | ||||
| C.1.9.4 | 6 (0.5%) | ||||
| 5a.2a.1 | 579 (50.1%) | D | 30 (2.6%) | ||
| D.1 | 9 (0.8%) | ||||
| D.3 | 362 (31.3%) | ||||
| D.5 | 178 (15.4%) | ||||
| A/H3 | 1,642 | ||||
| 2a.3a | 6 (0.4%) | G.1.3.1 | 6 (0.4%) | ||
| 2a.3a.1 | 1,636 (99.6%) | J.1 | 1 (0.1%) | ||
| J.1.1 | 7 (0.4%) | ||||
| J.2 | 1,503 (91.5%) | ||||
| J.2.1 | 42 (2.6%) | ||||
| J.2.2 | 83 (5.1%) | ||||
| B/Victoria | 270 | ||||
| 3a.2 | 270 (100%) | C.3 | 4 (1.5%) | ||
| C.5 | 30 (11.1%) | ||||
| C.5.1 | 132 (48.9%) | ||||
| C.5.5 | 1 (0.4%) | ||||
| C.5.6 | 37 (13.7%) | ||||
| C.5.7 | 66 (24.4%) | ||||
| B/Yamagata | 0 | ||||
| Y3 | 0 | Y3 | 0 | ||
Implications for Vaccine Effectiveness and Public Health
The dominance of specific clades and subclades within each influenza type has direct implications for how well the current flu vaccines will protect the U.S. population.If the circulating strains are antigenically similar to those included in the vaccine, protection is generally higher. However, even small differences can reduce vaccine effectiveness.
For example, the prevalence of the 2a.3a.1 clade in A/H3 viruses, accounting for 99.6% of the tested viruses, suggests that vaccines targeting this clade are likely to offer good protection against this particular strain. Though, continuous monitoring is essential to detect any shifts or emerging sub-variants that could compromise vaccine effectiveness.
The absence of B/Yamagata lineage viruses is also noteworthy. Since this lineage has not been circulating widely in recent years, it is no longer included in most flu vaccines. This highlights the dynamic nature of influenza surveillance and vaccine composition.
While the CDC’s report focuses primarily on genetic characterization, it’s crucial to remember the importance of monitoring antiviral resistance. The ability of influenza viruses to develop resistance to antiviral medications like Tamiflu poses a significant threat to public health, especially for vulnerable populations.
The CDC conducts ongoing testing to assess the susceptibility of circulating viruses to these medications. Any signs of increasing resistance would necessitate a reassessment of treatment strategies and potentially the development of new antiviral drugs.
Expert Recommendations for the U.S. Public
Based on the CDC’s latest findings, several key recommendations can be made to the U.S.public:
- Get vaccinated: The annual flu vaccine remains the most effective way to prevent influenza infection and its complications. Even if the vaccine isn’t a perfect match for all circulating strains, it can still reduce the severity and duration of illness.
- Practice good hygiene: Frequent handwashing, covering coughs and sneezes, and avoiding close contact with sick individuals can definitely help prevent the spread of influenza.
- Seek early treatment: If you develop flu symptoms, especially if you are at high risk of complications, consult your healthcare provider promptly. Antiviral medications can be effective if started early in the course of the illness.
- Stay informed: Keep up-to-date with the latest information from the CDC and your local health department regarding influenza activity and recommendations.
Looking Ahead: The Future of Flu Surveillance
the CDC’s influenza surveillance program is a vital component of public health infrastructure in the United States. Continued investment in this program is essential to ensure that the U.S. remains prepared for future flu seasons.
Emerging technologies, such as advanced genomic sequencing and data analytics, hold the promise of even more rapid and accurate influenza surveillance.These tools could enable earlier detection of emerging threats and more precise targeting of public health interventions.
By World-Today-News.com Expert journalist
Published: [Current Date]
Influenza and Respiratory Virus Update: Week 12, 2025
Across the united States, respiratory illnesses continue to circulate at levels above the national baseline, raising concerns among public health officials. The Centers for Disease Control and Prevention (CDC) is closely monitoring the situation, tracking influenza viruses, SARS-CoV-2 (the virus that causes COVID-19), RSV, and other respiratory pathogens.The latest data, covering the week ending March 22, 2025 (Week 12), reveals important trends in virus activity and antiviral susceptibility.
The CDC emphasizes the importance of comprehensive surveillance to understand the full picture of respiratory illness. “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,” the agency states.
A critical aspect of influenza surveillance is monitoring the susceptibility of circulating viruses to antiviral medications. This information is vital for guiding treatment decisions and ensuring that public health strategies remain effective. The CDC has tested viruses collected since September 29, 2024, for their susceptibility to commonly used antiviral drugs.
The data reveals some concerning trends. While most viruses remain susceptible, instances of reduced or highly reduced inhibition to certain antivirals have been detected. Specifically, some A(H1N1)pdm09 viruses exhibited highly reduced inhibition to oseltamivir (Tamiflu) and peramivir due to the NA-H275Y amino acid substitution. One A(H3N2) virus showed highly reduced inhibition to oseltamivir due to the NA-E119V amino acid substitution. Additionally, one A(H3N2) virus had reduced susceptibility to baloxavir (Xofluza).
These findings underscore the importance of ongoing surveillance and the potential need for alternative treatment strategies in certain cases. “Five A(H1N1)pdm09 viruses had NA-H275Y amino acid substitution conferring highly reduced inhibition by oseltamivir and peramivir,” the CDC reports. “One A(H3N2) virus had NA-E119V amino acid substitution and showed highly reduced inhibition by oseltamivir.”
Here’s a summary of the antiviral susceptibility testing:
| Antiviral Medication | Result | Total Viruses Tested | A/H1 | A/H3 | B/Victoria |
|---|---|---|---|---|---|
| Oseltamivir | Viruses Tested | 3,028 | 1,149 | 1,613 | 266 |
| Reduced Inhibition | 1 | 1 | 0 | 0 | |
| Highly Reduced Inhibition | 6 (0.2%) | 5 (0.4%) | 1 | 0 | |
| Peramivir | Viruses Tested | 3,028 | 1,149 | 1,613 | 266 |
| Reduced Inhibition | 0 | 0 | 0 | 0 | |
| Highly Reduced Inhibition | 5 (0.2%) | 5 (0.4%) | 0 | 0 | |
| Zanamivir | Viruses Tested | 3,028 | 1,149 | 1,613 | 266 |
| Reduced Inhibition | 0 | 0 | 0 | 0 | |
| Highly Reduced Inhibition | 0 | 0 | 0 | 0 | |
| Baloxavir | Viruses Tested | 2,903 | 1,042 | 1,604 | 257 |
| Decreased Susceptibility | 1 | 0 | 1 (0.1%) | 0 |
It’s important to note that adamantanes (amantadine and rimantadine) are not recommended for treating influenza A viruses due to high levels of resistance. The CDC does not present data from adamantane resistance testing.
Outpatient respiratory Illness Surveillance: ILINet Data
The U.S.Outpatient Influenza-like Illness Surveillance Network (ILINet) provides valuable insights into the prevalence of respiratory illness across the country. ILINet monitors outpatient visits for influenza-like illness (ILI), defined as fever plus cough or sore throat. It’s crucial to remember that ILI can be caused by various pathogens,including influenza,SARS-CoV-2,and RSV.
During Week 12, 3.3% of patient visits reported through ILINet were due to ILI. While this represents a slight decrease compared to the previous week (Week 11),it remains above the national baseline of 3.0% for the seventeenth consecutive week. This sustained elevation suggests ongoing respiratory virus activity in communities nationwide.
The percentage of visits for ILI decreased in all 10 HHS regions this week compared to last.Regions 1, 2, 3, 5, and 10 are above their respective baselines while regions 4, 6, 7, 8, and 9 are below their respective baselines. This regional variation highlights the importance of local monitoring and tailored public health responses.
Data also shows that the percentage of visits for respiratory illness decreased in all age groups (0-4 years, 5-24 years, 25-49 years, 50-64 years, and 65+ years) in Week 12 compared to Week 11. This suggests a potential easing of the burden across different demographics.
The CDC uses ILINet data to produce a measure of ILI activity by state/jurisdiction and Core Based Statistical Areas (CBSA). This information is visualized on an interactive map, providing a snapshot of respiratory illness activity across the country.
| Activity Level | Week 12 (Mar. 22, 2025) Jurisdictions | Week 11 (Mar.15, 2025) Jurisdictions | Week 12 (Mar. 22, 2025) CBSAs | week 11 (Mar. 15, 2025) CBSAs |
|---|---|---|---|---|
| Very High | 0 | 0 | 2 | 9 |
| High | 7 | 20 | 44 | 84 |
| Moderate | 13 | 13 | 77 | 122 |
| Low | 16 | 12 | 192 | 202 |
| Minimal | 17 | 9 | 372 | 283 |
| Insufficient Data | 2 | 1 | N/A | N/A |
Expert Insights and Practical Applications
The ongoing circulation of respiratory viruses and the emergence of antiviral resistance highlight the importance of several key strategies:
- Vaccination: Staying up-to-date on influenza and COVID-19 vaccines remains the most effective way to protect against severe illness.
- Early Detection and Testing: Prompt testing can help identify the specific virus causing illness, allowing for appropriate treatment decisions.
- Antiviral Use: Antiviral medications can be effective in treating influenza, especially when started early. However, healthcare providers should be aware of potential resistance patterns and consider alternative options when necessary.
- Preventive Measures: Practicing good hygiene, such as frequent handwashing and covering coughs and sneezes, can definitely help prevent the spread of respiratory viruses.
- Staying Informed: Regularly checking updates from the CDC and local health departments can provide the latest information on respiratory virus activity and recommendations.
Dr. [Fictional Medical Expert Name], a leading infectious disease specialist at [Fictional Hospital Name] in New York City, emphasizes the importance of vigilance. “While we’re seeing a slight decrease in ILI activity,it’s crucial to remain proactive,” dr. [Expert Name] states. “Vaccination, early detection, and appropriate antiviral use are essential tools in managing respiratory illnesses.”
The CDC provides detailed information about antiviral susceptibility test methods on its website: U.S. influenza Surveillance: Purpose and Methods.
Addressing Potential Counterarguments
Some might argue that the slight decrease in ILI activity indicates that the threat of respiratory viruses is diminishing. However, experts caution against complacency. The continued circulation of multiple viruses, coupled with the emergence of antiviral resistance, suggests that respiratory illnesses will likely remain a public health concern for the foreseeable future. Ongoing surveillance, research, and proactive prevention strategies are essential to mitigate the impact of these viruses on communities across the United States.
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Influenza Activity update: Week 12 Shows Declining Trends but High Hospitalization Rates
Published:
A comprehensive overview of influenza activity in the United States, focusing on data from Week 12 (ending March 22, 2025). While some indicators show a decrease in activity, hospitalization rates remain a significant concern.
National Overview
As of Week 12, several key indicators suggest a potential easing of influenza activity across the nation. Though, it’s crucial to understand the nuances within the data, particularly concerning hospitalization rates and regional variations.
Virologic Surveillance: Analyzing Flu Strains
Virologic surveillance provides critical insights into the circulating influenza strains. Understanding these strains helps inform public health strategies and vaccine effectiveness.
Key Findings
during Week 12, public health laboratories reported the following:
- Total Specimens Tested: 56,742
- Positive for Influenza: 4,051 (7.1%)
- Influenza A: 3,799 (93.8%)
- A(H1N1)pdm09: 1,570 (41.3%)
- A(H3N2): 2,229 (58.7%)
- Influenza B: 252 (6.2%)
- B/Victoria Lineage: 229 (90.9%)
The dominance of influenza A, particularly the A(H3N2) strain, continues to be a notable trend. The prevalence of the B/Victoria lineage among Influenza B viruses is also significant for understanding the current flu season’s dynamics.
| Virus Type | Count |
|---|---|
| Influenza A | 3,799 |
| Influenza B | 252 |
| A(H1N1)pdm09 | 1,570 |
| A(H3N2) | 2,229 |
| B/Victoria Lineage | 229 |
Outpatient Illness Surveillance: Tracking ILI Activity
The Influenza-like Illness (ILI) Surveillance Network (ILINet) monitors the proportion of outpatient visits for ILI. This provides insights into the burden of respiratory illness in communities across the U.S.
Key Findings
Nationally, 2.8% of outpatient visits reported through ILINet were for ILI. This is below the national baseline of 2.9%.
Regionally, the percentage of outpatient visits for ILI ranged from 1.3% to 4.4%.While most regions are at or below their baselines, some areas may still be experiencing elevated ILI activity.
It’s important to note that 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.
This highlights the need for comprehensive surveillance strategies.
*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.
National Syndromic Surveillance system (NSSP)
The NSSP tracks emergency department (ED) visits with a discharge diagnosis of influenza. This system provides a near real-time view of influenza-related healthcare utilization.
Key Findings
During Week 12,1.7% of ED visits had a discharge diagnosis of influenza, a decrease compared to the previous week. This decrease was observed across all 10 HHS regions and all age groups.
Hospitalization Surveillance: Monitoring severe Cases
hospitalization surveillance provides critical data on the severity of influenza infections, particularly among vulnerable populations.
FluSurv-Net
The influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties across 14 states, representing approximately 9% of the U.S. population.
Key Findings
between October 1, 2024, and March 22, 2025, FluSurv-NET sites reported a total of 36,748 laboratory-confirmed influenza-associated hospitalizations. The weekly hospitalization rate for Week 12 was 2.0 per 100,000 population.
The cumulative hospitalization rate observed in week 12 was 119.9 per 100,000 population, which is the highest cumulative hospitalization rate for Week 12 across all seasons since 2010-2011.
Among all hospitalizations:
- 97.1% were associated with influenza A virus
- 2.4% with influenza B virus
- 0.1% with influenza A and influenza B virus co-infection
- 0.4% with influenza virus for which the type was not determined
Among those with influenza A subtype information:
- 57.1% had A(H1N1)pdm09
- 42.9% had A(H3N2)
The highest cumulative hospitalization rate per 100,000 population was among adults aged 65 years and older (377.1), followed by adults aged 50-64 years (140.5), children aged 0-4 years (99.3), adults aged 18-49 years (48.6), and children aged 5-17 years (37.5).
When examining age-adjusted rates by race and ethnicity, the highest cumulative hospitalization rate per 100,000 population was among non-Hispanic black persons (202.5), followed by American Indian/Alaska Native persons (146.7), non-Hispanic White persons (103.4), Hispanic persons (99.0), and Asian/pacific Islander persons (75.0).
Among hospitalized adults with information on underlying medical conditions, 95.2% had at least one reported underlying medical condition; the most commonly reported were hypertension, cardiovascular disease, metabolic disease, and obesity. Among hospitalized women of childbearing age (15-49 years) with information on pregnancy status, 28.6% were pregnant. Among hospitalized children with information on underlying medical conditions, 52.9% had at least one reported underlying medical condition; the most commonly reported was asthma, followed by neurologic disease and obesity.
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.
Key Findings
Nationally, during Week 12, 12,990 laboratory-confirmed influenza-associated hospitalizations were reported. This week’s influenza-associated hospitalizations decreased compared to Week 11.
The weekly hospital admission rate observed in Week 12 was 3.9 per 100,000. The weekly rate of hospital admissions decreased in all 10 HHS regions and ranged from 2.1 (Region 9) to 6.8 (Region 3).
the highest hospital admission rate per 100,000 population was among those 65+ years (12.3),followed by 50-64 years (3.9), and 0-4 years (3.2).
Mortality surveillance provides a crucial measure of the impact of influenza on public health.
National Center for Health Statistics (NCHS) Mortality Surveillance
Based on NCHS mortality surveillance data available on March 27, 2025, 1.3% of the deaths that occurred during the week ending March 22, 2025 (Week 12), were due to influenza. This percentage decreased compared to Week 11.
Influenza-Associated Pediatric Mortality
Eight influenza-associated pediatric deaths occurring during the 2024-2025 season were reported to CDC during Week 12. The deaths occurred during Week 50 of 2024 (the week ending December 14, 2024) and during Weeks 8 through 11 of 2025 (the weeks ending February 22, 2025 and March 15, 2025).
Seven deaths were associated with influenza A viruses. Six of the influenza A viruses had subtyping performed; three were A(H1N1) viruses and three were A(H3N2) viruses. One death was associated with an influenza B virus with no lineage determined.
A total of 159 influenza-associated pediatric deaths occurring during the 2024-2025 season have been reported to CDC.
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 5% of the number of patients admitted 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 applications allow people to create customized, visual interpretations of influenza data, and also 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.
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.
