FluView: A Weekly Influenza Surveillance Report Prepared by the Influenza Division

2018-2019 Influenza Season Summary Weeks 21 – 39, May 19 - September 28, 2019

All data are preliminary and may change as more reports are received.

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.

U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.

The results of tests performed by clinical laboratories are summarized below.

	Week 39	Data Cumulative since May 19, 2018 (week 29)
No. of specimens tested	11,855	200,654
No. of positive specimens (%)	399 (3.4%)	5,320 (2.7%)
*Positive specimens by type*
Influenza A	110 (27.6%)	2,443 (45.9%)
Influenza B	289 (72.4%)	2,877 (54.1%)

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The results of tests performed by public health laboratories are summarized below.

	Week 39	Data Cumulative since May 19, 2019 (week 21)
No. of specimens tested	300	7,637
No. of positive specimens*	38	1,737
*Positive specimens by type/subtype*
Influenza A	29 (76.3%)	1,213 (69.8%)
(H1N1)pdm09	8 (32.0%)	324 (28.1%)
H3N2	17 (68.0%)	830 (71.9%)
Subtyping not performed	4	59
Influenza B	9 (23.7%)	524 (30.2%)
Yamagata lineage	0 (0%)	27 (6.1%)
Victoria lineage	9 (100.0%)	413 (93.9%)
Lineage not performed	0	84

*The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.

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Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.

Outpatient Illness Surveillance:

Nationwide during week 39, 1.3% 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 2.2%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.) For weeks 21-39, the percent of patient visits for ILI was below the national baseline for all weeks and ranged from 0.7% - 1.4%. In addition, no region exceeded their region-specific baseline during this time.

Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.

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Influenza-Associated Hospitalizations:

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts all age 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.

Additional FluSurv-NET data can be found at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.

Pneumonia and Influenza (P&I) Mortality Surveillance:

Based on National Center for Health Statistics (NCHS) mortality surveillance data available on October 3, 2019, 5.0% of the deaths occurring during the week ending September 21, 2019 (week 38) were due to P&I. This percentage is below the epidemic threshold of 5.7% for week 38. The P&I percentage was below the weekly epidemic threshold for all weeks since week 21.

Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available on FluView Interactive (http://gis.cdc.gov/grasp/fluview/mortality.html). Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

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Influenza-Associated Pediatric Mortality:

No influenza-associated pediatric deaths were reported to CDC during week 39. During weeks 21-39, 25 pediatric deaths were reported; 5 occurred during those weeks. Among the 5 deaths that occurred after week 20, 2 were influenza A viruses that were not subtyped, 1 was an influenza A (H1N1)pdm09 influenza virus, 1 was an influenza A(H3) virus, and 1 was an influenza B/Victoria lineage virus.

A total of 136 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.

Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactive (http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html).

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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.

U.S. State and local influenza surveillance: Click on 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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