All data are preliminary and may change as more reports are received.
During week 46 (November 9-15, 2014), influenza activity was low in the United States.
|HHS Surveillance Regions*||Data cumulative since September 28, 2014 (week 40)|
|Out-patient ILI†||% positive for flu‡||Number of jurisdictions reporting regional or widespread activity§||2009 H1N1||A (H3)||A(Subtyping not performed)||B||Pediatric Deaths|
|Nation||Normal||9.3%||6 of 54||26||1,458||1,969||926||1|
|Region 1||Normal||1.2%||1 of 6||1||17||14||14||0|
|Region 2||Normal||0.9%||1 of 4||6||92||15||26||0|
|Region 3||Normal||3.9%||0 of 6||0||77||50||33||0|
|Region 4||Normal||11.0%||1 of 8||2||276||1,114||527||1|
|Region 5||Normal||7.6%||0 of 6||9||132||230||39||0|
|Region 6||Normal||14.0%||2 of 5||2||257||363||185||0|
|Region 7||Normal||4.6%||0 of 4||1||63||36||34||0|
|Region 8||Normal||4.3%||0 of 6||0||66||46||19||0|
|Region 9||Normal||3.8%||0 of 5||4||116||57||39||0|
|Region 10||Normal||18.2%||1 of 4||1||362||44||10||0|
*HHS regions (Region 1 CT, ME, MA, NH, RI, VT; Region 2: NJ, NY, Puerto Rico, US Virgin Islands; Region 3: DE, DC, MD, PA, VA, WV; Region 4: AL, FL, GA, KY, MS, NC, SC, TN; Region 5: IL, IN, MI, MN, OH, WI; Region 6: AR, LA, NM, OK, TX; Region 7: IA, KS, MO, NE; Region 8: CO, MT, ND, SD, UT, WY; Region 9: AZ, CA, Guam, HI, NV; and Region 10: AK, ID, OR, WA).
† Elevated means the % of visits for ILI is at or above the national or region-specific baseline
‡ National data are for current week; regional data are for the most recent three weeks
§ Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands
WHO and NREVSS collaborating laboratories located in all 50 states, Puerto Rico, and the District of Columbia report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza virus type and influenza A virus subtype. The results of tests performed during the current week are summarized in the table below. Region specific data are available at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.
|No. of specimens tested||10,304|
|No. of positive specimens (%)||955 (9.3%)|
|Positive specimens by type/subtype|
|Influenza A||836 (87.5%)|
|2009 H1N1||0 (0.0%)|
|Subytping not performed||579 (69.3%)|
|Influenza B||119 (12.5%)|
CDC has antigenically characterized 52 influenza viruses (one 2009 H1N1 virus, 34 influenza A (H3N2) viruses, and 17 influenza B viruses) collected by U.S. laboratories since October 1, 2014 by hemagglutination inhibition (HI).
2009 H1N1 :
Influenza A (H3N2) :
Influenza B : Ten (58.8%) of the influenza B viruses tested belong to B/Yamagata/16/88 lineage and the remaining seven (41.2%) influenza B viruses tested belong to B/Victoria/02/87 lineage.
*CDC conducts antigenic characterization of influenza viruses year-round to compare how similar currently circulating influenza viruses are to those included in the influenza vaccine, and to monitor for changes in circulating influenza viruses.
Testing of 2009 H1N1, influenza A (H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir and zanamivir) is performed at CDC using a functional assay. Additional 2009 H1N1 and influenza A (H3N2) clinical samples are tested for mutations of the virus known to confer oseltamivir resistance. The data summarized below combine the results of both testing methods. These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with antiviral-resistant virus.
High levels of resistance to the adamantanes (amantadine and rimantadine) persist among 2009 influenza A (H1N1) and A (H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
|Virus Samples tested (n)||Resistant Viruses, Number (%)||Virus Samples tested (n)||Resistant Viruses, Number (%)|
|Influenza A (H3N2)||15||0 (0.0)||15||0 (0.0)|
|Influenza B||7||0 (0.0)||7||0 (0.0)|
|2009 H1N1||2||0 (0.0)||2||0 (0.0)|
In the United States, all recently circulating influenza viruses have been susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir and zanamivir; however, rare sporadic instances of oseltamivir-resistant 2009 H1N1 and A (H3N2) viruses have been detected worldwide. Antiviral treatment with oseltamivir or zanamivir is recommended as early as possible for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at http://www.cdc.gov/flu/antivirals/index.htm.
During week 46, 5.0% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.4% for week 46.
For the 2014-2015 influenza season, CDC/Influenza Division and the National Center for Health Statistics (NCHS) are collaborating on a pilot project to use NCHS mortality surveillance data for the rapid assessment of pneumonia and influenza (P&I) mortality. To view the data, please click here.
No influenza-associated pediatric deaths were reported to CDC during week 46. To date, one influenza-associated pediatric death has been reported for the 2014-2015 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.
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. FluSurv-NET estimated hospitalization rates will be updated weekly starting later this season. 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.
Nationwide during week 46, 1.6% 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 2.0%.
(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
Additional data are available at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.
On a regional level, the percentage of outpatient visits for ILI ranged from 0.8% to 2.3% during week 46. All 10 regions reported a proportion of outpatient visits for ILI below their region-specific baseline levels.
Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
During week 46, the following ILI activity levels were experienced:
*This map uses the proportion of outpatient visits to health care providers for influenza-like illness to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
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.
Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map is preliminary and may change as more data is received.
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.
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 46, the following influenza activity was reported:
Flu Activity data in XML Format | View Full Screen
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.
Google Flu Trends: Google Flu Trends uses aggregated Google search data in a model created in collaboration with CDC to estimate influenza activity in the United States. For more information and activity estimates from the United States and worldwide, see http://www.google.org/flutrends/
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 at http://www.euroflu.org/index.php and visit the European Centre for Disease Prevention and Control at http://ecdc.europa.eu/en/publications/surveillance_reports/influenza/Pages/weekly_influenza_surveillance_overview.aspx
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
In addition to the eight data components of CDC influenza surveillance for the 2014-2015 influenza season, the use of National Center for Health Statistics (NCHS) pneumonia and influenza mortality surveillance data for the rapid assessment of influenza-associated mortality will be piloted. An overview of influenza surveillance, including a description of the NCHS mortality surveillance data, is available here.--------------------------------------------------------------------------------