Weekly U.S. Influenza Surveillance Report

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%.

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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.

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

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

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

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

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

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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