sharon sanders
Editor-in-Chief & President
FluView Summary ending on October 3, 2020
Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVIDView.
Key Updates for Week 40, ending October 3, 2020
Seasonal influenza activity in the United States remains low.
Viruses
Clinical Labs
The percentage of respiratory specimens testing positive for influenza at clinical laboratories is 0.21% this week.
Public Health Labs
Influenza activity has been low over the summer months. Few specimens have tested positive in the public health labs during the most recent weeks.
Virus Characterization
Influenza virus characterization information will be updated weekly starting later this season.
Illness
Outpatient Illness: ILINet
1.1% of visits to a health care provider were for ILI. ILI activity remains below the national baseline of 2.6% but increased slightly from the previous week.
Outpatient Illness: ILINet Activity Map
This week, 1 jurisdiction experienced low activity while the remaining jurisdictions experienced minimal activity.
Geographic Spread
Because of the ongoing COVID-19 pandemic, this system will suspend data collection for the 2020-21 influenza season.
Severe Disease
Hospitalizations
Hospitalization rates will be updated weekly starting later this season.
P&I Mortality
7.0% of deaths were attributed to pneumonia, influenza, or COVID-19 (PIC). This is above the epidemic threshold of 5.6%.
Pediatric Deaths
No influenza-associated pediatric deaths occurring during the 2020-21 season have been reported to CDC. 189 deaths occurring during the 2019-20 season have been reported.
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
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 ScreenPublic 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
Influenza Virus Characterization
CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.
Virus characterization data will be updated weekly starting later this season when sufficient numbers of specimens have been tested.
Outpatient Illness Surveillance
ILINet
Nationwide during week 40, 1.1% 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 2.6%.
Healthcare seeking behaviors have changed dramatically during the COVID-19 pandemic. While outpatient ILI activity remains low, many people are accessing the healthcare system in alternative settings. Therefore, while traditional healthcare providers are not seeing increased numbers of cases of ILI, it is important to evaluate other sources of surveillance data to obtain a complete and accurate picture of both COVID-19 and influenza activity.
View Chart Data (current season only) | View Full ScreenILI Activity Map
Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
*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
Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists
The geographic spread of influenza as reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity. Due to the impact of COVID-19 on ILI surveillance, and the fact that the state and territorial epidemiologists report relies heavily on ILI activity, reporting for this system will be suspended for the 2020-21 influenza season. Data from previous seasons is available on FluView Interactive.
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. FluSurv-NET estimated hospitalization rates will be updated weekly starting later this season.
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 NCHS mortality surveillance data available on October 8, 2020, 7.0% of the deaths occurring during the week ending October 3, 2020 (week 40) were due to pneumonia, influenza, and COVID-19 (PIC). This percentage is above the epidemic threshold of 5.6% for week 40.
Weekly mortality surveillance data include a combination of machine coded and manually coded causes of death collected from death certificates. Percentages of deaths due to pneumonia, influenza, or COVID-19 (PIC) are higher among manually coded records than more rapidly available machine coded records. Due to the additional time needed for manual coding, the initially reported PIC percentages are likely to increase as more data are received and processed.
View Chart Dataexcel icon | View Full Screen
Additional pneumonia and influenza mortality surveillance information for current and past seasons:
Surveillance Methods | FluView Interactive
Influenza-Associated Pediatric Mortality
No influenza-associated pediatric deaths occurring during the 2020-21 season have been reported to CDC.
View Full Screen
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.
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.
World Health Organization:
Additional influenza surveillance information from participating WHO member nations is available through
FluNetexternal icon and the Global Epidemiology Reports.external icon
WHO Collaborating Centers for Influenza:
Australiaexternal icon, Chinaexternal icon, Japanexternal icon, the United Kingdomexternal icon, and the United States (CDC in Atlanta, Georgia)
Europe:
The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Controlexternal icon.
Public Health Agency of Canada:
The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch reportexternal icon.
Public Health England:
The most up-to-date influenza information from the United Kingdom is available from Public Health Englandexternal icon.
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.
Page last reviewed: October 9, 2020, 11:00 AM
https://www.cdc.gov/flu/weekly/weeklyarchives2020-2021/week40.htm
Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVIDView.
Key Updates for Week 40, ending October 3, 2020
Seasonal influenza activity in the United States remains low.
Viruses
Clinical Labs
The percentage of respiratory specimens testing positive for influenza at clinical laboratories is 0.21% this week.
Public Health Labs
Influenza activity has been low over the summer months. Few specimens have tested positive in the public health labs during the most recent weeks.
Virus Characterization
Influenza virus characterization information will be updated weekly starting later this season.
Illness
Outpatient Illness: ILINet
1.1% of visits to a health care provider were for ILI. ILI activity remains below the national baseline of 2.6% but increased slightly from the previous week.
Outpatient Illness: ILINet Activity Map
This week, 1 jurisdiction experienced low activity while the remaining jurisdictions experienced minimal activity.
Geographic Spread
Because of the ongoing COVID-19 pandemic, this system will suspend data collection for the 2020-21 influenza season.
Severe Disease
Hospitalizations
Hospitalization rates will be updated weekly starting later this season.
P&I Mortality
7.0% of deaths were attributed to pneumonia, influenza, or COVID-19 (PIC). This is above the epidemic threshold of 5.6%.
Pediatric Deaths
No influenza-associated pediatric deaths occurring during the 2020-21 season have been reported to CDC. 189 deaths occurring during the 2019-20 season have been reported.
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
- An annual flu vaccine is the best way to protect against flu and its potentially serious complications.
- CDC recommends everyone 6 months or older get a flu vaccine by the end of October.
- There also are flu antiviral drugs that can be used to treat flu illness.
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.
| No. of specimens tested | 7,774 | 7,923 |
| No. of positive specimens (%) | 22 (0.3%) | 17 (0.2%) |
| Positive specimens by type | ||
| Influenza A | 13 (59.1%) | 9 (52.9%) |
| Influenza B | 9 (40.9%) | 8 (47.1%) |
View Chart Data | View Full ScreenPublic 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.
| No. of specimens tested | 1,718 | 5,755 |
| No. of positive specimens | 1 | 1 |
| Positive specimens by type/subtype | ||
| Influenza A | 1 (100.0%) | 1 (100.0%) |
| (H1N1)pdm09 | 0 (0.0%) | 0 (0.0%) |
| H3N2 | 0 (0.0%) | 0 (0.0%) |
| Subtyping not performed | 1 | 1 |
| Influenza B | 0 (0.0%) | 0 (0.0%) |
| Yamagata lineage | 0 (0.0%) | 0 (0.0%) |
| Victoria lineage | 0 (0.0%) | 0 (0.0%) |
| Lineage not performed | 0 | 0 |
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
Influenza Virus Characterization
CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.
Virus characterization data will be updated weekly starting later this season when sufficient numbers of specimens have been tested.
Outpatient Illness Surveillance
ILINet
Nationwide during week 40, 1.1% 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 2.6%.
Healthcare seeking behaviors have changed dramatically during the COVID-19 pandemic. While outpatient ILI activity remains low, many people are accessing the healthcare system in alternative settings. Therefore, while traditional healthcare providers are not seeing increased numbers of cases of ILI, it is important to evaluate other sources of surveillance data to obtain a complete and accurate picture of both COVID-19 and influenza activity.
View Chart Data (current season only) | View Full ScreenILI 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 40 (Week ending Oct. 3, 2020) | Week 39 (Week ending Sept. 26, 2020) | Week 40 (Week ending Oct. 3, 2020) | Week 39 (Week ending Sept. 26, 2020) | |
| Very High | 0 | 0 | 0 | 0 |
| High | 0 | 1 | 1 | 2 |
| Moderate | 0 | 1 | 4 | 3 |
| Low | 1 | 0 | 14 | 20 |
| Minimal | 52 | 49 | 569 | 523 |
| Insufficient Data | 1 | 3 | 341 | 381 |
*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
Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists
The geographic spread of influenza as reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity. Due to the impact of COVID-19 on ILI surveillance, and the fact that the state and territorial epidemiologists report relies heavily on ILI activity, reporting for this system will be suspended for the 2020-21 influenza season. Data from previous seasons is available on FluView Interactive.
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. FluSurv-NET estimated hospitalization rates will be updated weekly starting later this season.
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 NCHS mortality surveillance data available on October 8, 2020, 7.0% of the deaths occurring during the week ending October 3, 2020 (week 40) were due to pneumonia, influenza, and COVID-19 (PIC). This percentage is above the epidemic threshold of 5.6% for week 40.
Weekly mortality surveillance data include a combination of machine coded and manually coded causes of death collected from death certificates. Percentages of deaths due to pneumonia, influenza, or COVID-19 (PIC) are higher among manually coded records than more rapidly available machine coded records. Due to the additional time needed for manual coding, the initially reported PIC percentages are likely to increase as more data are received and processed.
View Chart Dataexcel icon | View Full Screen
Additional pneumonia and influenza mortality surveillance information for current and past seasons:
Surveillance Methods | FluView Interactive
Influenza-Associated Pediatric Mortality
No influenza-associated pediatric deaths occurring during the 2020-21 season have been reported to CDC.
View Full Screen 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.
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.
Additional influenza surveillance information from participating WHO member nations is available through
FluNetexternal icon and the Global Epidemiology Reports.external icon
WHO Collaborating Centers for Influenza:
Australiaexternal icon, Chinaexternal icon, Japanexternal icon, the United Kingdomexternal icon, and the United States (CDC in Atlanta, Georgia)
Europe:
The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Controlexternal icon.
Public Health Agency of Canada:
The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch reportexternal icon.
Public Health England:
The most up-to-date influenza information from the United Kingdom is available from Public Health Englandexternal icon.
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.
Page last reviewed: October 9, 2020, 11:00 AM
https://www.cdc.gov/flu/weekly/weeklyarchives2020-2021/week40.htm
