Weekly U.S. Influenza Surveillance Report
Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution. CDC is tracking the COVID-19 pandemic in a weekly publication called COVIDView.
Laboratory confirmed flu activity as reported by clinical laboratories is now low. Influenza-like illness activity continues to decrease and is below the national baseline. The percent of deaths due to pneumonia or influenza (P&I) is high but the increase is due primarily to COVID-19, not influenza. Reported pediatric flu deaths for the season are high at 169.
Viruses
Severe Disease
All data 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.
Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.
Key Points
- Nationally, influenza activity is now low.
- With ongoing declines in influenza activity and the continued effects of the COVID-19 pandemic, FluView will be abbreviated for the remainder of the 2019-2020 season.
- More detailed interpretation of data and more COVID-19 specific information can be found in COVIDView.
U.S. Virologic Surveillance
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) are used to monitor whether influenza activity is increasing or decreasing.
View Chart Data | View Full Screen
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 viruses that belong to each influenza subtype/lineage.
View Chart Data | View Full Screen
Additional virologic surveillance information for current and past seasons:
Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
Outpatient Illness Surveillance
ILINet
Nationwide during week 16, 2.2% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.4%.
View Chart Data (current season only) | View Full Screen
On a regional level, the percentage of outpatient visits for ILI ranged from 1.1% to 5.4% during week 16. The percent of outpatient visits for ILI decreased in all regions compared to last week. Regions 1, 2, 3, and 10 reported a percentage of outpatient visits for ILI above their region-specific baselines. All other regions are below their region-specific baselines.
ILI Activity Map
Data collected in ILINet are used to produce a measure of ILI activity* by state.
During week 16, the following ILI activity levels were experienced:
- Very High – one state (New Jersey)
- High – the District of Columbia, New York City, and five states (Connecticut, Louisiana, Maryland, Massachusetts, and New York)
- Moderate – Puerto Rico and two states (Idaho and Wisconsin)
- Low - eight states (Georgia, Illinois, New Mexico, Oklahoma, Pennsylvania, South Carolina, Vermont, and Virginia)
- Minimal - 34 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Hawaii, Indiana, Iowa, Kansas, Kentucky, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, North Carolina, North Dakota, Ohio, Oregon, Rhode Island, South Dakota, Tennessee, Texas, Utah, Washington, West Virginia, and Wyoming)
- Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.
*Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state 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
Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists
The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
During week 16, the following influenza activity was reported:
- Regional – Puerto Rico and 9 states (Georgia, Idaho, Indiana, Louisiana, Maryland, Nevada, South Carolina, Tennessee and Wisconsin)
- Local – 12 states (Alabama, Arizona, Maine, Massachusetts, Montana, New Hampshire, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania and Virginia)
- Sporadic – the District of Columbia, the U.S. Virgin Islands and 26 states (Alaska, Arkansas, California, Colorado, Connecticut, Florida, Hawaii, Illinois, Iowa, Kansas, Kentucky, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New York, North Dakota, Oregon, South Dakota, Texas, Utah, Vermont, Washington, West Virginia and Wyoming)
- No Activity – three states (Delaware, New Mexico and Rhode Island)
- Guam did not report.
Additional geographic spread surveillance information for current and past seasons:
Surveillance Methods | FluView Interactive
Influenza-Associated Hospitalizations
The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
A total of 19,932 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and April 18, 2020 with a cumulative hospitalization rate of 68.6 per 100,000 population.
Additional hospitalization surveillance information for current and past seasons and additional age groups:
Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics
Pneumonia and Influenza (P&I) Mortality Surveillance
Based on National Center for Health Statistics (NCHS) mortality surveillance data available on April 23, 2020, 11.4% of the deaths occurring during the week ending April 18, 2020 (week 16) were due to P&I. This percentage is above the epidemic threshold of 6.9% for week 16.
View Chart Data | View Full Screen
Additional pneumonia and influenza mortality surveillance information for current and past seasons:
Surveillance Methods | FluView Interactive
Influenza-Associated Pediatric Mortality
One influenza-associated pediatric death occurring during the 2019-2020 season was reported to CDC during week 16. It was associated with an influenza B virus with no lineage determined and occurred during week 5 (the week ending February 1, 2020).
A total of 169 influenza-associated pediatric deaths occurring during the 2019-2020 season have been reported to CDC.
Additional pediatric mortality surveillance information for current and past seasons:
Surveillance Methods | FluView Interactive
Additional National and International Influenza 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. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
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 at https://www.cdc.gov/niosh/topics/absences/default.html
U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information
World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports
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.
An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
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