US - 2015-16 FluView: Influenza Weekly Summary Report - Weeks 43 - 13

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http://www.cdc.gov/flu/weekly/

Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories in week 43 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories is low.

Pneumonia and Influenza Mortality: Based on NCHS mortality surveillance data available on November 5, 2015, 5.8% of the deaths occurring during the week ending October 17, 2015 (week 41) were due to P&I. This percentage is below the epidemic threshold of 6.4% for week 41. 122 Cities Mortality Reporting System: During week 43, 5.5% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.1% for week 43.

Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.

Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.4%, which is below the national baseline of 2.1%. All 10 regions reported ILI below region-specific baseline levels. Puerto Rico experienced low ILI activity, New York City and 50 states experienced minimal ILI activity, and the District of Columbia had insufficient data.

Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as regional; two states reported local activity; Puerto Rico and 40 states reported sporadic activity; and the District of Columbia, the U.S. Virgin Islands and eight states reported no influenza activity.

Outpatient Illness Surveillance: Nationwide during week 43, 1.4% 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 2.1%.

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During week 44 (November 1-7, 2015), influenza activity was low in the United States.

Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories in week 44 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories is low.

Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.

Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.4%, which is below the national baseline of 2.1%. All 10 regions reported ILI below region-specific baseline levels. Puerto Rico experienced moderate ILI activity, New York City and 50 states experienced minimal ILI activity, and the District of Columbia had insufficient data.

Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico reported regional activity; four states reported local activity; the District of Columbia and 39 states reported sporadic activity; and the U.S. Virgin Islands and seven states reported no influenza activity.

CDC has characterized 335 influenza viruses [14 A (H1N1)pdm09, 250 A (H3N2), and 71 influenza B viruses] collected by U.S. laboratories during May 24 ? September 30, 2015.

Influenza A Virus [264]
A (H1N1)pdm09 [14]: All 14 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere.
A (H3N2) [250]: All 250 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) component of the 2015-2016 Northern Hemisphere vaccine.
A subset of 104 H3N2 viruses also were antigenically characterized; 103 of 104 (99%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [71]: Forty-four (62%) of the influenza B viruses characterized belonged to B/Yamagata/16/88 lineage and the remaining 27 (38%) influenza B viruses characterized belonged to B/Victoria/02/87 lineage.

Yamagata Lineage [44]: All 44 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.

Victoria Lineage [27]: All 27 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, the virus that is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccine.

CDC has characterized 10 influenza viruses [one A (H1N1)pdm09, eight A (H3N2), and one influenza B virus] collected by U.S. laboratories since October 1, 2015.

The eight influenza A (H3N2) viruses collected since October 1, 2015 have been genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) component of the 2015-2016 Northern Hemisphere vaccine. Six viruses (one A (H1N1)pdm09, four A (H3N2), and one B/Yamagata-lineage) collected since October 1, 2015 have been antigenically characterized. All six were similar to the 2015-2016 Northern Hemisphere influenza vaccine components.

Pneumonia and Influenza (P&I) Mortality Surveillance:
NCHS Mortality Surveillance Data:

Based on NCHS mortality surveillance data available on November 12, 2015, 5.8% of the deaths occurring during the week ending October 24, 2015 (week 42) were due to P&I. This percentage is below the epidemic threshold of 6.5% for week 42.

122 Cities Mortality Reporting System:

During week 44, 5.7% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.2% for week 44.

http://www.cdc.gov/flu/weekly/

[mixin]

During week 45 (November 8-14, 2015), influenza activity increased slightly in the United States.

Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories in week 45 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories is low.

Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
Based on NCHS mortality surveillance data available on November 19, 2015, 5.7% of the deaths occurring during the week ending October 31, 2015 (week 43) were due to P&I. This percentage is below the epidemic threshold of 6.6% for week 43.
122 Cities Mortality Reporting System: During week 45, 5.3% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.3% for week 45.

Influenza-associated Pediatric Deaths: One influenza-associated pediatric death was reported to CDC during week 45. This death was associated with an influenza A virus for which no subtyping was performed and occurred during week 44 (the week ending November 7, 2015). A total of one influenza-associated pediatric death has been reported during the 2015-2016 season. This death occurred in California as per MMWR http://www.cdc.gov/mmwr/preview/mmwr...cid=mm6445md_w

Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.6%, which is below the national baseline of 2.1%. Two of 10 regions reported ILI at or above region-specific baseline levels. One state experienced moderate ILI activity; Puerto Rico and two states experienced low ILI activity; New York City and 47 states experienced minimal ILI activity; and the District of Columbia had insufficient data.

Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico reported regional activity; four states reported local activity; 40 states reported sporadic activity; and the District of Columbia, the U.S. Virgin Islands, and six states reported no influenza activity.

Influenza Virus Characterization:
CDC has characterized 337 influenza viruses [14 A (H1N1)pdm09, 252 A (H3N2), and 71 influenza B viruses] collected by U.S. laboratories during May 24 ? September 30, 2015.

Influenza A Virus [266]
* A (H1N1)pdm09 [14]: All 14 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere.
* A (H3N2) [252]: All 252 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) component of the 2015-2016 Northern Hemisphere vaccine.

A subset of 106 H3N2 viruses also were antigenically characterized; 105 of 106 (99%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.
Influenza B Virus [71]: Forty-four (62%) of the influenza B viruses characterized belonged to B/Yamagata/16/88 lineage and the remaining 27 (38%) influenza B viruses characterized belonged to B/Victoria/02/87 lineage.

Yamagata Lineage [44]: All 44 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.

Victoria Lineage [27]: All 27 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, the virus that is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccine.

CDC has characterized 12 influenza viruses [one A (H1N1)pdm09, 10 A (H3N2), and one influenza B virus] collected by U.S. laboratories since October 1, 2015.

The 10 influenza A (H3N2) viruses collected since October 1, 2015 have been genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) component of the 2015-2016 Northern Hemisphere vaccine. Six viruses (one A (H1N1)pdm09, four A (H3N2), and one B/Yamagata-lineage) collected since October 1, 2015 have been antigenically characterized. All six were similar to the 2015-2016 Northern Hemisphere influenza vaccine components.

http://www.cdc.gov/flu/weekly/#modalIdString_CDCTable_3

[sharon sanders]

2015-2016 Influenza Season Week 46 ending November 21, 2015

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

During week 46 (November 15-21, 2015), influenza activity increased slightly in the United States but remained low overall.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 46 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: One influenza-associated pediatric death was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.6%, which is below the national baseline of 2.1%. Two of 10 regions reported ILI at or above region-specific baseline levels. One state experienced moderate ILI activity; New York City Puerto Rico and 49 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico reported regional activity; five states reported local activity; 39 states reported sporadic activity; and the District of Columbia, the U.S. Virgin Islands, and six states reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Normal	1 of 53	1.1%	44	234	21	8	10	47	2
Normal	0 of 6	0.3%	2	14	0	0	0	0	0
Normal	0 of 4	0.4%	7	15	0	0	0	4	0
Elevated	0 of 6	0.7%	4	12	2	0	4	0	0
Normal	1 of 8	2.9%	2	19	7	0	0	10	0
Normal	0 of 6	0.9%	18	20	3	1	2	1	0
Elevated	0 of 5	1.4%	0	12	0	1	0	6	1
Normal	0 of 4	0.4%	1	21	0	1	1	1	0
Normal	0 of 6	0.2%	2	10	1	2	1	0	0
Normal	0 of 4	1.2%	7	72	7	3	2	24	1
Normal	0 of 4	0.3%	1	39	1	0	0	1	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

10,793	88,825
120 (1.1%)	1,074 (1.2%)
58 (48.3%)	657 (61.2%)
62 (51.7%)	417 (38.8%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

638	7,354
24	364
18 (75.0%)	299 (82.1%)
5 (27.8%)	44 (14.7%)
10 (55.6%)	234 (78.3%)
3 (16.7%)	21 (7.0%)
6 (25.0%)	65 (17.9%)
3 (50.0%)	10 (15.4%)
0 (0.0%)	8 (12.3%)
3 (50.0%)	47 (72.3%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data | View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. This data is used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data has been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 345 influenza viruses [14 A (H1N1)pdm09, 260 A (H3N2), and 71 influenza B viruses] collected by U.S. laboratories during May 24-September 30, 2015.
Influenza A Virus [274]

• A (H1N1)pdm09 [14]: All 14 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere.

• A (H3N2) [260]: All 260 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to cell propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 118 H3N2 viruses also were antigenically characterized; 117 of 118 (99%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [71]: Forty-four (62%) of the influenza B viruses characterized belonged to B/Yamagata/16/88 lineage and the remaining 27 (38%) influenza B viruses characterized belonged to B/Victoria/02/87 lineage.
Yamagata Lineage [44]:All 44 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [27]: All 27 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, the virus that is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccine.
CDC has characterized 20 influenza viruses [one A (H1N1)pdm09, 18 A (H3N2), and one influenza B virus] collected by U.S. laboratories since October 1, 2015.
The 18 influenza A (H3N2) viruses collected since October 1, 2015 have been genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus propagated in cell culture and representing the 2015-2016 Northern Hemisphere vaccine component. Ten viruses (one A (H1N1)pdm09, eight A (H3N2), and one B/Yamagata-lineage) collected since October 1, 2015 have been antigenically characterized. All ten were similar to the 2015-2016 Northern Hemisphere influenza vaccine components.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

5	0 (0.0)	5	0 (0.0)	5	0 (0.0)
14	0 (0.0)	14	0 (0.0)	14	0 (0.0)
9	0 (0.0)	9	0 (0.0)	9	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on November 25, 2015, 5.9% of the deaths occurring during the week ending November 7, 2015 (week 44) were due to P&I. This percentage is below the epidemic threshold of 6.7% for week 44.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 46, 6.0% 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.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

One influenza-associated pediatric death was reported to CDC during week 46. This death was associated with an influenza B virus and occurred during week 44 (the week ending November 7, 2015). A total of two influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

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 2.1%.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.5% to 3.9% during week 46. Two regions (Regions 3 and 6) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.



ILINet State Activity Indicator Map:

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 calculated:

• One state (South Carolina) experienced moderate ILI activity.
• New York City, Puerto Rico and 49 states (Alaska, Alabama, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Iowa, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, West Virginia, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 46, the following influenza activity was reported:

• Widespread influenza activity was reported by Guam.
• Regional influenza activity was reported by Puerto Rico.
• Local influenza activity was reported by five states (Hawaii, Iowa, Kentucky, New Hampshire, and Utah).
• Sporadic influenza activity was reported by 39 states (Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by the District of Columbia, the U.S. Virgin Islands, and six states (Alabama, Delaware, Kansas, Maryland, Mississippi, and Rhode Island).

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.flunewseurope.org/ and visit the European Centre for Disease Prevention and Control at http://ecdc.europa.eu/en/publication..._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



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.

[sharon sanders]

2015-2016 Influenza Season Week 47 ending November 28, 2015

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

During week 47 (November 22-28, 2015), influenza activity increased slightly in the United States but remained low overall.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 47 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.9%, which is below the national baseline of 2.1%. Three of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and two states experienced moderate ILI activity; four states experienced low ILI activity; New York City and 44 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico reported regional activity; seven states reported local activity; the District of Columbia, the U.S. Virgin Islands, and 38 states reported sporadic activity; and five states reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Normal	3 of 53	1.5%	55	262	16	8	13	50	2
Normal	0 of 6	0.4%	4	14	0	0	0	0	0
Normal	1 of 4	0.4%	7	15	0	0	0	4	0
Elevated	0 of 6	0.6%	5	13	1	0	4	0	0
Elevated	1 of 8	3.4%	2	24	3	0	0	12	0
Normal	0 of 6	0.8%	21	20	3	1	3	1	0
Elevated	1 of 5	1.4%	0	14	0	1	1	6	1
Normal	0 of 4	0.2%	1	21	0	1	1	1	0
Normal	0 of 6	0.2%	5	14	1	2	1	0	0
Normal	0 of 4	0.8%	9	86	7	3	3	25	1
Normal	0 of 4	0.2%	1	41	1	0	0	1	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

11,288	102,675
171 (1.5%)	1,268 (1.2%)
103 (60.2%)	772 (60.9%)
68 (39.8%)	496 (39.1%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

481	8,488
13	404
12 (92.3%)	333 (82.4%)
5 (41.7%)	55 (16.5%)
7 (58.3%)	262 (78.7%)
0 (0%)	16 (4.8%)
1 (7.7%)	71 (17.6%)
0 (0%)	13 (18.3%)
0 (0%)	8 (11.3%)
1 (100%)	50 (70.4%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data | View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. This data is used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data has been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 62 influenza viruses [18 A (H1N1)pdm09, 43 A (H3N2), and 1 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [61]

• A (H1N1)pdm09 [18]: All 18 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [43]: All 43 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 16 H3N2 viruses also were antigenically characterized; 15 of 16 (93.8%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [1]
Yamagata Lineage [1]: One B/Yamagata-lineage virus was antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [0]: No B/Victoria-lineage viruses were antigenically characterized.
CDC has characterized 359 influenza viruses [17 A (H1N1)pdm09, 271 A (H3N2), and 71 influenza B virus] collected by U.S. laboratories from May 24-September 30,2015.
The 271 influenza A(H3N2) viruses collected from May 24-September 30, 2015 have been genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) cell-propagated reference virus representing the 2015-2016 Northern Hemisphere vaccine. Two hundred and six viruses (17 A (H1N1)pdm09, 118 A (H3N2), 44 B/Yamagata-lineage, and 27 B/Victoria-lineage) collected from May 24-September 30, 2015 have been antigenically characterized. All but one virus were similar to the reference viruses representing the 2015-2016 Northern Hemisphere influenza vaccine components.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

11	0 (0.0)	11	0 (0.0)	11	0 (0.0)
33	0 (0.0)	33	0 (0.0)	33	0 (0.0)
12	0 (0.0)	12	0 (0.0)	12	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on December 3, 2015, 5.9% of the deaths occurring during the week ending November 14, 2015 (week 45) were due to P&I. This percentage is below the epidemic threshold of 6.8% for week 45.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 47, 6.1% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.5% for week 47.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

No influenza-associated pediatric deaths were reported to CDC during week 47. A total of two influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

Nationwide during week 47, 1.9% 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 2.1%.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.6% to 4.3% during week 47. Three regions (Regions 3, 4, and 6) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.



ILINet State Activity Indicator Map:

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 47, the following ILI activity levels were calculated:

• Puerto Rico and two states (Oklahoma and South Carolina) experienced moderate ILI activity.
• Four states (Arizona, Mississippi, New Jersey, and Virginia) experienced low ILI activity.
• New York City, Puerto Rico, and 44 states (Alabama, Alaska, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 47, the following influenza activity was reported:

• Widespread influenza activity was reported by Guam.
• Regional influenza activity was reported by Puerto Rico.
• Local influenza activity was reported by seven states (Iowa, Maryland, Massachusetts, New Hampshire, North Carolina, Oregon, and Utah).
• Sporadic influenza activity was reported by the District of Columbia, the U.S. Virgin Islands, and 38 states (Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Texas, Vermont, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by five states (Alabama, Mississippi, Rhode Island, Tennessee, and Virginia).

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.flunewseurope.org/ and visit the European Centre for Disease Prevention and Control at http://ecdc.europa.eu/en/publication..._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



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.

[sharon sanders]

2015-2016 Influenza Season Week 48 ending December 5, 2015

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

During week 48 (November 29 – December 5, 2015), influenza activity increased slightly in the United States but remained low overall.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 48 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported, including one influenza-associated pediatric death that occurred during the 2014-2015 season.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.8%, which is below the national baseline of 2.1%. Four of 10 regions reported ILI at or above region-specific baseline levels. One state experienced high ILI activity; Puerto Rico and four states experienced low ILI activity; New York City and 45 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico reported regional activity; 10 states reported local activity; the U.S. Virgin Islands and 37 states reported sporadic activity; and the District of Columbia and three states reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Normal	1 of 53	1.6%	66	291	21	15	21	65	3
Normal	0 of 6	0.3%	5	15	0	1	0	1	0
Elevated	0 of 4	0.9%	8	15	0	0	0	4	0
Elevated	0 of 6	0.8%	6	16	4	1	9	1	0
Elevated	1 of 8	3.5%	3	25	3	0	0	14	1
Normal	0 of 6	0.8%	23	23	4	1	3	1	0
Elevated	0 of 5	0.9%	0	14	0	1	2	6	1
Normal	0 of 4	0.5%	1	22	0	1	1	1	0
Normal	0 of 6	0.2%	7	18	1	3	1	1	0
Normal	0 of 4	0.7%	11	95	8	7	5	34	1
Normal	0 of 4	0.9%	2	48	1	0	0	2	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

11,509	117,483
185 (1.6%)	1,495 (1.3%)
122 (65.9%)	916 (61.3%)
63 (34.1%)	579 (38.7%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

787	9,893
36	479
23 (63.9%)	378 (78.9%)
5 (21.7%)	66 (17.5%)
15 (65.2%)	291 (77.0%)
3 (13.0%)	21 (5.6%)
13 (36.1%)	101 (21.1%)
3 (23.1%)	21 (20.8%)
3 (23.1%)	15 (14.9%)
7 (53.8%)	65 (64.4%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data | View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 91 influenza viruses [18 A (H1N1)pdm09, 57 A (H3N2), and 16 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [75]

• A (H1N1)pdm09 [18]: All 18 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [57]: All 57 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 23 H3N2 viruses also were antigenically characterized; 22 of 23 (95.7%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [16]
Yamagata Lineage [9]: Nine B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [7]: Seven B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
CDC has characterized 375 influenza viruses [17 A (H1N1)pdm09, 277 A (H3N2), and 81 influenza B virus] collected by U.S. laboratories from May 24-September 30,2015.
The 277 influenza A(H3N2) viruses collected from May 24-September 30, 2015 have been genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to A/Switzerland/9715293/2013, the influenza A (H3N2) cell-propagated reference virus representing the 2015-2016 Northern Hemisphere vaccine. Two hundred and nineteen viruses (17 A (H1N1)pdm09, 121 A (H3N2), 52 B/Yamagata-lineage, and 29 B/Victoria-lineage) collected from May 24-September 30, 2015 have been antigenically characterized. All but one virus (one influenza A (H3N2) virus) were similar to the reference viruses representing the 2015-2016 Northern Hemisphere influenza vaccine components.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

17	0 (0.0)	17	0 (0.0)	17	0 (0.0)
34	0 (0.0)	34	0 (0.0)	34	0 (0.0)
18	0 (0.0)	18	0 (0.0)	18	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on December 10, 2015, 5.9% of the deaths occurring during the week ending November 21, 2015 (week 46) were due to P&I. This percentage is below the epidemic threshold of 6.9% for week 46.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 48, 6.1% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.6% for week 48.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

Two influenza-associated pediatric deaths were reported to CDC during week 48. One death was associated with an influenza B virus and occurred during week 48 (the week ending December 5, 2015). A total of three influenza-associated pediatric deaths have been reported during the 2015-2016 season.
One death was associated with an influenza B virus and occurred during the 2014-2015 season and brings the total number of reported pediatric deaths occurring during that season to 148.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

Nationwide during week 48, 1.8% 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 2.1%.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.6% to 4.3% during week 48. Four regions (Regions 2, 3, 4, and 6) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.



ILINet State Activity Indicator Map:

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 48, the following ILI activity levels were calculated:

• One state (South Carolina) experienced high ILI activity.
• Puerto Rico and four states (Arizona, Mississippi, New Jersey, and Texas) experienced low ILI activity.
• New York City and 45 states (Alabama, Alaska, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 48, the following influenza activity was reported:

• Widespread influenza activity was reported by Guam.
• Regional influenza activity was reported by Puerto Rico.
• Local influenza activity was reported by 10 states (Connecticut, Iowa, Kentucky, Maryland, Massachusetts, Nevada, New Hampshire, North Carolina, Oregon, and Texas).
• Sporadic influenza activity was reported by the U.S. Virgin Islands and 37 states (Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Kansas, Louisiana, Maine, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by the District of Columbia and three states (Alabama, Mississippi, and Rhode Island).

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.

http://www.cdc.gov/flu/weekly/weeklyarchives2015-2016/Week48.htm

[sharon sanders]

2015-2016 Influenza Season Week 49 ending December 12, 2015

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

During week 49 (December 6-12, 2015), influenza activity increased slightly in the United States but remained low overall.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 49 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Novel Influenza A Virus: One human infection with a novel influenza A virus was reported.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.9%, which is below the national baseline of 2.1%. Four of 10 regions reported ILI at or above region-specific baseline levels. One state experienced high ILI activity; Puerto Rico and one state experienced moderate ILI activity; New York City and two states experienced low ILI activity; 46 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico and two states reported regional activity; 12 states reported local activity; the District of Columbia, the U.S. Virgin Islands, and 33 states reported sporadic activity; and three states reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Normal	3 of 53	1.7%	104	338	25	17	31	81	3
Normal	0 of 6	0.6%	8	15	0	1	0	1	0
Elevated	2 of 4	1.0%	14	37	0	0	0	4	0
Elevated	0 of 6	0.5%	9	17	4	1	11	1	0
Elevated	1 of 8	3.9%	3	25	5	0	0	23	1
Normal	0 of 6	0.7%	32	26	6	1	5	3	0
Elevated	0 of 5	1.2%	0	15	0	1	2	8	1
Normal	0 of 4	0.6%	1	22	0	1	1	1	0
Normal	0 of 6	0.5%	17	23	1	3	1	1	0
Normal	0 of 4	1.0%	21	105	8	7	6	35	1
Normal	0 of 4	1.6%	2	53	1	2	5	4	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

12,525	133,503
208 (1.7%)	1,765 (1.3%)
117 (56.3%)	1,061 (60.1%)
91 (43.8%)	704 (39.9%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

786	11,639
41	596
30 (73.2%)	467 (78.4%)
17 (56.7%)	104 (22.3%)
11 (36.7%)	338 (72.4%)
2 (6.7%)	25 (5.4%)
11 (26.8%)	129 (21.6%)
4 (36.4%)	31 (24.0%)
0 (0%)	17 (13.2%)
7 (63.6%)	81 (62.8%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data | View Full Screen Novel Influenza A Virus:

One human infection with a novel influenza A virus was reported by the state of Minnesota. The person was infected with an influenza A (H1N1) variant (H1N1v) virus. The patient was not hospitalized and has fully recovered from their illness. The patient lived and worked in an area near where swine were housed but no direct contact with swine was reported in the week prior to illness onset. No ongoing human-to-human transmission has been identified.
Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be more fully appreciated and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza infection in humans, and strategies to interact safely with swine can be found at http://www.cdc.gov/flu/swineflu/index.htm.
Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 134 influenza viruses [18 A (H1N1)pdm09, 100 A (H3N2), and 16 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [118]

• A (H1N1)pdm09 [18]: All 18 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [100]: All 100 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 53 H3N2 viruses also were antigenically characterized; 52 of 53 (98.1%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [16]
Yamagata Lineage [9]: Nine B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [7]: Seven B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

25	1 (4.0)	25	0 (0.0)	25	1 (4.0)
117	0 (0.0)	117	0 (0.0)	117	0 (0.0)
21	0 (0.0)	21	0 (0.0)	21	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on December 17, 2015, 5.9% of the deaths occurring during the week ending November 28, 2015 (week 47) were due to P&I. This percentage is below the epidemic threshold of 7.0% for week 47.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 49, 6.0% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.7% for week 49.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

No influenza-associated pediatric deaths were reported to CDC during week 49. A total of three influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

Nationwide during week 49, 1.9% 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 2.1%.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.6% to 4.4% during week 49. Four regions (Regions 2, 3, 4, and 6) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 49, the following ILI activity levels were calculated:

• One state (South Carolina) experienced high ILI activity.
• Puerto Rico and one state (New Jersey) experienced moderate ILI activity.
• New York City and two states (Minnesota and Virginia) experienced low ILI activity.
• 46 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 49, the following influenza activity was reported:

• Widespread influenza activity was reported by Guam.
• Regional influenza activity was reported by Puerto Rico and two states (Maryland and New Hampshire).
• Local influenza activity was reported by 12 states (Alabama, Arizona, Connecticut, Idaho, Iowa, Kentucky, Massachusetts, Nevada, New Jersey, North Carolina, Texas, and Utah).
• Sporadic influenza activity was reported by the District of Columbia, the U.S. Virgin Islands, and 33 states (Alaska, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Kansas, Louisiana, Maine, Michigan, Minnesota, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by three states (Delaware, Mississippi, and Rhode Island).

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.

http://www.cdc.gov/flu/weekly/weeklyarchives2015-2016/Week49.htm

[sharon sanders]

2015-2016 Influenza Season Week 50 ending December 19, 2015

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

During week 50 (December 13-19, 2015), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 50 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: One influenza-associated pediatric death was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.2%, which is above the national baseline of 2.1%. Four of 10 regions reported ILI at or above region-specific baseline levels. One state experienced high ILI activity; Puerto Rico and two states experienced moderate ILI activity; New York City and three states experienced low ILI activity; 44 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam, Puerto Rico, and five states was reported as regional; the U.S. Virgin Islands and 14 states reported local activity; the District of Columbia and 27 states reported sporadic activity; and four states reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Elevated	4 of 53	2.9%	137	365	36	20	41	88	4
Normal	0 of 6	0.5%	8	15	0	1	0	1	0
Elevated	2 of 4	0.9%	14	38	0	0	0	4	0
Elevated	0 of 6	0.5%	10	17	4	1	13	1	0
Elevated	1 of 8	5.1%	3	25	7	0	0	24	2
Normal	0 of 6	0.7%	43	30	11	1	7	3	0
Elevated	1 of 5	1.0%	1	19	0	1	2	8	1
Normal	0 of 4	1.0%	1	22	1	1	1	1	0
Normal	0 of 6	0.8%	24	26	1	3	1	1	0
Normal	0 of 4	1.5%	21	114	11	9	10	40	1
Normal	0 of 4	2.5%	12	59	1	3	7	5	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
? Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

12,890	149,359
372 (2.9%)	2,159 (1.5%)
211 (56.7%)	1,286 (59.6%)
161 (43.3%)	879 (40.4%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

707	12,821
55	687
43 (78.2%)	538 (78.3%)
23 (53.5%)	137 (25.5%)
6 (14.0%)	365 (67.8%)
6 (14.0%)	36 (6.7%)
12 (21.8%)	149 (21.7%)
6 (50.0%)	41 (27.5%)
2 (16.7%)	20 (13.4%)
4 (33.3%)	88 (59.1%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data | View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014?2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 155 influenza viruses [34 A (H1N1)pdm09, 105 A (H3N2), and 16 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [139]

• A (H1N1)pdm09 [34]: All 34 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [105]: All 105 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 66 H3N2 viruses also were antigenically characterized; 65 of 66 (98.5%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [16]
Yamagata Lineage [9]: All nine (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [7]: All seven (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

27	1 (3.7)	27	0 (0.0)	27	1 (3.7)
126	0 (0.0)	126	0 (0.0)	126	0 (0.0)
29	0 (0.0)	29	0 (0.0)	29	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on December 24, 2015, 6.2% of the deaths occurring during the week ending December 5, 2015 (week 48) were due to P&I. This percentage is below the epidemic threshold of 7.1% for week 48.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 50, 6.3% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.8% for week 50.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

One influenza-associated pediatric death was reported to CDC during week 50. This death was associated with an influenza A virus for which no subtyping was performed and occurred during week 50 (the week ending December 19, 2015). A total of four influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

Nationwide during week 50, 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 above the national baseline of 2.1%.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.6% to 4.8% during week 50. Four regions (Regions 2, 3, 4, and 6) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 50, the following ILI activity levels were calculated:

• One state (South Carolina) experienced high ILI activity.
• Puerto Rico and two states (New Jersey and Texas) experienced moderate ILI activity.
• New York City and three states (Alabama, Georgia, and Virginia) experienced low ILI activity.
• 44 states (Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 50, the following influenza activity was reported:

• Regional influenza activity was reported by Guam, Puerto Rico and five states (Kentucky, Maryland, Minnesota, North Carolina, and Pennsylvania).
• Local influenza activity was reported by the U.S. Virgin Islands and 14 states (Alabama, Arizona, Connecticut, Idaho, Indiana, Iowa, Massachusetts, Nevada, New Hampshire, New Jersey, New Mexico, Oregon, Texas, and Virginia).
• Sporadic influenza activity was reported by the District of Columbia and 27 states (Alaska, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Kansas, Louisiana, Maine, Michigan, Missouri, Montana, Nebraska, New York, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by four states (Delaware, Illinois, Mississippi, and Rhode Island).

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, visithttp://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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and theGlobal 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 athttps://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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• Page last reviewed: December 28, 2015
• Page last updated: December 28, 2015
• Content source:
  • Centers for Disease Control and Prevention

http://www.cdc.gov/flu/weekly/

[sharon sanders]

2015-2016 Influenza Season Week 51 ending December 26, 2015

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

During week 51 (December 20-26, 2015), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 51 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.6%, which is above the national baseline of 2.1%. Six of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and two states experienced high ILI activity; three states experienced moderate ILI activity; New York City and nine states experienced low ILI activity; 36 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam and one state was reported as widespread; five states reported regional activity; 12 states reported local activity; 29 states reported sporadic activity; the District of Columbia and three states reported no influenza activity; and Puerto Rico and the U.S. Virgin Islands did not report.

National and Regional Summary of Select Surveillance Components

Elevated	6 of 53	2.5%	201	399	36	21	54	96	4
Elevated	0 of 6	0.8%	8	17	0	1	0	1	0
Elevated	2 of 4	0.7%	17	55	0	0	0	5	0
Elevated	1 of 6	0.5%	10	17	5	2	14	1	0
Elevated	2 of 8	5.6%	6	26	8	0	0	25	2
Normal	0 of 6	0.9%	58	34	8	1	8	3	0
Elevated	0 of 5	1.2%	1	20	0	1	2	8	1
Elevated	0 of 4	1.0%	2	22	2	1	1	1	0
Normal	0 of 6	1.2%	35	27	1	3	7	2	0
Normal	1 of 4	1.9%	47	122	11	9	15	44	1
Normal	0 of 4	2.3%	17	59	1	3	7	6	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

11,448	163,304
282 (2.5%)	2,459 (1.5%)
157 (55.7%)	1,455 (59.2%)
125 (44.3%)	1,004 (40.8%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

586	14,104
38	807
32 (84.2%)	636 (78.8%)
23 (71.9%)	201 (31.6%)
6 (18.8%)	399 (62.7%)
3 (9.4%)	36 (5.7%)
6 (15.8%)	171 (21.2%)
4 (66.7%)	54 (31.6%)
0 (0%)	21 (12.3%)
2 (33.3%)	96 (56.1%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data | View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 170 influenza viruses [34 A (H1N1)pdm09, 112 A (H3N2), and 24 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [146]

• A (H1N1)pdm09 [34]: All 34 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [112]: All 112 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 66 H3N2 viruses also were antigenically characterized; 65 of 66 (98.5%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [24]
Yamagata Lineage [17]: All 17 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [7]: All seven (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

40	1 (2.5)	39	0 (0.0)	40	1 (2.5)
138	0 (0.0)	138	0 (0.0)	138	0 (0.0)
38	0 (0.0)	38	0 (0.0)	38	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on December 31, 2015, 6.0% of the deaths occurring during the week ending December 12, 2015 (week 49) were due to P&I. This percentage is below the epidemic threshold of 7.2% for week 49.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 51, 5.8% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.9% for week 51.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

No influenza-associated pediatric deaths were reported to CDC during week 51. A total of four influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

Nationwide during week 51, 2.6% 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 above the national baseline of 2.1%.

The increase in the percentage of patient visits for ILI may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.7% to 5.0% during week 51. Six regions (Regions 1, 2, 3, 4, 6 and 7) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 51, the following ILI activity levels were calculated:

• Puerto Rico and two states (New Jersey and South Carolina) experienced high ILI activity.
• Three states (Arizona, Georgia, and Virginia) experienced moderate ILI activity.
• New York City and nine states (Illinois, Louisiana, Maryland, Minnesota, Mississippi, North Carolina, Oklahoma, Pennsylvania, and Texas) experienced low ILI activity.
• 36 states (Alabama, Alaska, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Idaho, Indiana, Iowa, Kansas, Kentucky, Maine, Massachusetts, Michigan, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Dakota, Ohio, Oregon, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 51, the following influenza activity was reported:

• Widespread influenza activity was reported by Guam and one state (North Carolina).
• Regional influenza activity was reported by five states (Maryland, Massachusetts, New Hampshire, Pennsylvania and Virginia).
• Local influenza activity was reported by 12 states (Arizona, Connecticut, Indiana, Iowa, Kentucky, Minnesota, Nevada, New Jersey, New Mexico, Oregon, Texas, and Utah).
• Sporadic influenza activity was reported by 29 states (Alabama, Alaska, Arkansas, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Kansas, Louisiana, Maine, Michigan, Missouri, Montana, Nebraska, New York, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Vermont, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by the District of Columbia and three states (Mississippi, Rhode Island, and Tennessee).
• Puerto Rico and the U.S. Virgin Islands did not report.

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.

[sharon sanders]

2015-2016 Influenza Season Week 52 ending January 2, 2016

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

During week 52 (December 26, 2015-January 2, 2016), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 52 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Novel Influenza A Virus: One human infection with a novel influenza A virus was reported.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.8%, which is above the national baseline of 2.1%. Seven of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and two states experienced high ILI activity; New York City and two states experienced moderate ILI activity; seven states experienced low ILI activity; 39 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam and two states were reported as widespread; six states reported regional activity; 13 states reported local activity; the U.S. Virgin Islands and 27 states reported sporadic activity; the District of Columbia and two states reported no influenza activity; and Puerto Rico did not report.

National and Regional Summary of Select Surveillance Components

Elevated	6 of 53	1.8%	290	437	44	22	73	115	6
Elevated	0 of 6	0.8%	9	17	0	1	0	1	0
Elevated	3 of 4	1.3%	20	55	2	0	0	8	0
Elevated	1 of 6	1.1%	13	23	12	2	16	2	0
Elevated	1 of 8	5.1%	7	27	9	0	0	25	3
Normal	0 of 6	0.9%	72	34	11	1	10	4	0
Elevated	1 of 5	1.4%	2	21	0	1	2	11	1
Elevated	0 of 4	0.8%	6	23	1	2	1	1	0
Normal	0 of 6	2.4%	38	35	1	3	17	3	0
Normal	0 of 4	3.2%	72	143	7	9	20	48	2
Normal	0 of 4	3.0%	21	59	1	3	7	12	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
? Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Beginning in the 2015-2016 influenza season, reports from public health and clinical laboratories are presented separately in both FluView and FluView Interactive. Influenza testing practices differ in public health and clinical laboratories but both sources provide valuable information for monitoring influenza activity. Clinical laboratories primarily test respiratory specimens for diagnostic purposes and data from these laboratories provide useful information on the timing and intensity of influenza activity. Public health laboratories primarily test specimens for surveillance purposes to understand what influenza viruses are circulating throughout their jurisdiction and the population groups being affected. However, in order to obtain enough specimens to produce this detailed information in an efficient manner, public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory. Because of this, monitoring the percent of specimens testing positive for influenza in a public health laboratory is less useful, but fortunately, is not necessary when clinical laboratory data is available.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

13,373	181,844
247 (1.8%)	2,818 (1.5%)
157 (63.6%)	1,682 (59.7%)
90 (36.4%)	1,136 (40.3%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

759	15,658
91	981
74 (81.3%)	771 (78.6%)
47 (63.5%)	290 (37.6%)
19 (25.7%)	437 (56.7%)
8 (10.8%)	44 (5.7%)
17 (18.7%)	210 (21.4%)
4 (23.5%)	73 (34.8%)
1 (5.9%)	22 (10.5%)
12 (70.6%)	115 (54.8%)

*Percent positive 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


View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data |View Full Screen Novel Influenza A Virus:

One human infection with a novel influenza A virus was reported by the state of New Jersey. The person was infected with an influenza A (H3N2) variant (H3N2v) virus. The patient was not hospitalized and has fully recovered from their illness. The patient visited a farm near where swine are frequently housed but no direct contact with swine was reported in the week prior to illness onset. No ongoing human-to-human transmission has been identified.
Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be more fully appreciated and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza infection in humans, and strategies to interact safely with swine can be found at http://www.cdc.gov/flu/swineflu/index.htm.
Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014?2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 192 influenza viruses [49 A (H1N1)pdm09, 119 A (H3N2), and 24 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [168]

• A (H1N1)pdm09 [49]: All 49 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [119]: All 119 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 74 H3N2 viruses also were antigenically characterized; 73 of 74 (98.6%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [24]
Yamagata Lineage [17]: All 17 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [7]: All seven (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

46	1 (2.2)	46	0 (0.0)	46	1 (2.2)
145	0 (0.0)	145	0 (0.0)	145	0 (0.0)
41	0 (0.0)	41	0 (0.0)	41	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on January 7, 2016, 6.1% of the deaths occurring during the week ending December 19, 2015 (week 50) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 50.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 52, 5.7% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.0% for week 52.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

Two influenza-associated pediatric deaths were reported to CDC during week 52. One death was associated with an influenza A (H3) virus and occurred during week 51 (the week ending December 26, 2015) and one death was associated with an influenza A (H1N1)pdm09 virus and occurred during week 52 (the week ending January 2, 2016). A total of six influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


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. 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.



Outpatient Illness Surveillance:

Nationwide during week 52, 2.8% 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 above the national baseline of 2.1%.

The increase in the percentage of patient visits for ILI may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
(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/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.8% to 5.3% during week 52. Seven regions (Regions 1, 2, 3, 4, 6, 8, and 9) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 52, the following ILI activity levels were calculated:

• Puerto Rico and two states (New Jersey and South Carolina) experienced high ILI activity.
• New York City and two states (Maryland and Texas) experienced moderate ILI activity.
• Seven states (Arizona, California, Colorado, Georgia, Oklahoma, Pennsylvania, and Virginia) experienced low ILI activity.
• 39 states (Alabama, Alaska, Arkansas, Connecticut, Delaware, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 52, the following influenza activity was reported:

• Widespread influenza activity was reported by Guam and two states (Maryland and North Carolina).
• Regional influenza activity was reported by six states (Connecticut, Iowa, Massachusetts, New Hampshire, Pennsylvania, and Virginia).
• Local influenza activity was reported by 13 states (Arizona, California, Kentucky, Maine, Nevada, New Jersey, New Mexico, North Dakota, Oklahoma, Oregon, Texas, Utah, and Vermont).
• Sporadic influenza activity was reported by the U.S. Virgin Islands and 27 states (Alaska, Arkansas, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Kansas, Louisiana, Michigan, Minnesota, Missouri, Montana, Nebraska, New York, Ohio, Rhode Island, South Carolina, South Dakota, Tennessee, Washington, West Virginia, Wisconsin, and Wyoming).
• No influenza activity was reported by the District of Columbia and two states (Alabama and Mississippi).
• Puerto Rico did not report.

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, visithttp://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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and theGlobal 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 athttps://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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• Page last reviewed: January 8, 2016
• Page last updated: January 8, 2016
• Content source:
  • Centers for Disease Control and Prevention

http://www.cdc.gov/flu/weekly/

[Ronan Kelly]

2015-2016 Influenza Season Week 1 ending January 9, 2016

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

During week 1 (January 3-9, 2016), laboratory data indicated that influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 1 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: One influenza-associated pediatric death was reported.
• Influenza-associated Hospitalizations: A cumulative rate for the season of 1.5 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.0%, which is below the national baseline of 2.1%. Four of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and one state experienced high ILI activity; New York City and seven states experienced low ILI activity; 42 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Guam, Puerto Rico, and nine states were reported as regional; 11 states reported local activity; the U.S. Virgin Islands and 28 states reported sporadic activity; and the District of Columbia and two states reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Normal	2 of 53	3.0%	421	480	65	33	104	134	7
Elevated	0 of 6	1.1%	11	18	0	1	0	1	0
Normal	1 of 4	1.5%	26	69	2	1	0	8	1
Elevated	0 of 6	1.2%	22	24	11	3	17	2	0
Elevated	1 of 8	5.2%	11	29	18	1	0	41	3
Normal	0 of 6	1.1%	80	34	24	1	12	4	0
Elevated	0 of 5	1.6%	5	21	0	2	4	9	1
Normal	0 of 4	0.6%	9	23	0	2	1	1	0
Normal	0 of 6	2.6%	92	31	1	4	28	2	0
Normal	0 of 4	5.4%	135	167	8	13	31	52	2
Normal	0 of 4	3.8%	30	54	1	5	11	14	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
? Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

14,269	200,873
428 (3.0%)	3,469 (1.7%)
292 (68.2%)	2,081 (60.0%)
136 (31.8%)	1,388 (40.0%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

929	17,545
112	1,237
94 (83.9%)	966 (78.1%)
58 (61.7%)	421 (43.6%)
15 (16.0%)	480 (49.7%)
21 (22.3%)	65 (6.7%)
18 (16.1%)	271 (21.9%)
8 (44.4%)	104 (38.4%)
4 (22.2%)	33 (12.2%)
6 (33.3%)	134 (49.4%)

*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.


View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data |View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014?2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 209 influenza viruses [49 A (H1N1)pdm09, 128 A (H3N2), and 32 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [177]

• A (H1N1)pdm09 [49]: All 49 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [128]: All 128 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 78 H3N2 viruses also were antigenically characterized; 77 of 78 (98.7%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [32]
Yamagata Lineage [25]: All 25 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [7]: All seven (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

75	1 (1.3)	64	0 (0.0)	75	1 (1.3)
166	0 (0.0)	166	0 (0.0)	160	0 (0.0)
64	0 (0.0)	64	0 (0.0)	64	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on January 14, 2016, 5.8% of the deaths occurring during the week ending December 26, 2015 (week 51) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 51.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 1, 6.4% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.0% for week 1.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

One influenza-associated pediatric death was reported to CDC during week 1. This death was associated with an influenza B virus and occurred during week 49 (the week ending December 12, 2015). A total of seven influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


Influenza-Associated Hospitalizations:

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).
The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; IA, MI, OH, RI, and UT during the 2012-2013 season; and MI, OH, and UT during the 2013-2014, 2014-15 and 2015-16 seasons.
Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.
Between October 1, 2015 and January 9, 2016, 423 laboratory-confirmed influenza-associated hospitalizations were reported. The overall hospitalization rate was 1.5 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 years (5.2 per 100,000 population), followed by children aged 0-4 years (2.9 per 100,000 population). Among all hospitalizations, 269 (64.8%) were associated with influenza A, 120 (28.9%) with influenza B, 15 (3.6%) with influenza A and B co-infection, and 11 (2.7%) had no virus type information. Among those with influenza A subtype information, 42 (70.0%) were A(H1N1)pdm09 and 18 (30.0%) were A(H3N2) virus.
Clinical findings are preliminary and based on 136 (32.2%) cases with complete medical chart abstraction. The majority (85.1%) of hospitalized adults had at least one reported underlying medical condition; the most commonly reported were metabolic disorders, cardiovascular disease, and obesity. There were 22 hospitalized children with complete medical chart abstraction, 14 (63.6%) had no identified underlying medical conditions. The most commonly reported underlying medical conditions among pediatric patients were asthma, chronic lung disease, neurologic disorders and obesity. Among the 6 hospitalized women of childbearing age (15-44 years), 2 were pregnant.
Additional FluSurv-NET data can be found at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html andhttp://gis.cdc.gov/grasp/fluview/FluHospChars.html.

Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics? (NCHS) population estimates for the counties included in the surveillance catchment area.
View Interactive Application | View Full Screen | View PowerPoint Presentation
FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseasesinclude conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
View Interactive Application | View Full Screen | View PowerPoint Presentation



Outpatient Illness Surveillance:

Nationwide during week 1, 2.0% 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 2.1%. (ILI is defined as fever (temperature of 100?F [37.8?C] or greater) and cough and/or sore throat.)
The increase in the percentage of patient visits for ILI in previous weeks may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 0.5% to 4.3% during week 1. Four regions (Regions 1, 3, 4, and 6) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 1, the following ILI activity levels were calculated:

• Puerto Rico and one state (South Carolina) experienced high ILI activity.
• New York City and seven states (Arizona, Connecticut, Illinois, Maryland, Pennsylvania, Texas, and Virginia) experienced low ILI activity.
• 42 states (Alabama, Alaska, Arkansas, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 1, the following influenza activity was reported:

• Regional influenza activity was reported by Guam, Puerto Rico, and nine states (Arizona, California, Connecticut, Iowa, Massachusetts, New Hampshire, North Carolina, Pennsylvania, and Virginia).
• Local influenza activity was reported by 11 states (Indiana, Kentucky, Maryland, Nevada, New Jersey, New Mexico, Oklahoma, Oregon, Texas, Utah, and Vermont).
• Sporadic influenza activity was reported by the U.S. Virgin Islands and 28 states (Alaska, Arkansas, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Kansas, Louisiana, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New York, North Dakota, Ohio, Rhode Island, South Carolina, South Dakota, Washington, West Virginia, Wisconsin, and Wyoming).
• The District of Columbia and two states (Alabama and Tennessee) reported no influenza activity.

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, visithttp://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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and theGlobal 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 athttps://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.
--------------------------------------------------------------------------------

• Full report also available as PDF

http://www.cdc.gov/flu/weekly/

[sharon sanders]

2015-2016 Influenza Season Week 2 ending January 16, 2016

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

During week 2 (January 10-16, 2016), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 2 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the NCHS Mortality Surveillance System and above the system-specific epidemic threshold in the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.
• Influenza-associated Hospitalizations: A cumulative rate for the season of 1.8 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.1%, which is at the national baseline of 2.1%. Six of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico experienced high ILI activity; three states experienced moderate ILI activity; New York City and four states experienced low ILI activity; 43 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in three states was reported as widespread; Puerto Rico and 10 states reported regional activity; Guam and 12 states reported local activity; the U.S. Virgin Islands and 24 states reported sporadic activity; and the District of Columbia and one state reported no influenza activity.

National and Regional Summary of Select Surveillance Components

Elevated	4 of 53	4.2%	591	558	95	46	152	150	7
Elevated	0 of 6	1.7%	12	19	0	1	1	2	0
Elevated	1 of 4	1.8%	28	69	3	1	0	9	1
Elevated	1 of 6	0.8%	24	28	16	3	18	2	0
Elevated	1 of 8	6.1%	14	36	23	1	0	46	3
Normal	0 of 6	1.5%	86	37	35	1	17	2	0
Elevated	0 of 5	1.8%	9	25	1	2	5	11	1
Normal	0 of 4	1.1%	14	23	3	2	1	1	0
Normal	0 of 6	3.4%	126	32	1	6	44	2	0
Normal	1 of 4	6.7%	243	224	12	20	52	61	2
Elevated	0 of 4	6.2%	35	65	1	9	14	14	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

13,598	221,668
565 (4.2%)	4,158 (1.9%)
398 (70.4%)	2,561 (61.6%)
167 (29.6%)	1,597 (38.4%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

845	19,270
181	1,592
142 (78.5%)	1,244 (78.1%)
88 (62.0%)	591 (47.5%)
32 (22.5%)	558 (44.9%)
22 (15.5%)	95 (7.6%)
39 (21.5%)	348 (21.9%)
15 (38.5%)	152 (43.7%)
6 (15.4%)	46 (13.2%)
18 (46.2%)	150 (43.1%)

*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.


View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data |View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 259 influenza viruses [74 A (H1N1)pdm09, 135 A (H3N2), and 50 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [209]

• A (H1N1)pdm09 [74]: All 74 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [135]: All 135 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 80 H3N2 viruses also were antigenically characterized; 79 of 80 (98.8%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [50]
Yamagata Lineage [25]: All 25 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
Victoria Lineage [25]: All 25 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.
Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

93	1 (1.1)	81	0 (0.0)	93	1 (1.1)
180	0 (0.0)	180	0 (0.0)	174	0 (0.0)
77	0 (0.0)	77	0 (0.0)	77	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on January 21, 2016, 6.5% of the deaths occurring during the week ending January 2, 2016 (week 52) were due to P&I. This percentage is below the epidemic threshold of 7.4% for week 52.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 2, 7.6% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was above the epidemic threshold of 7.1% for week 2.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

No influenza-associated pediatric deaths were reported to CDC during week 2. A total of seven influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


Influenza-Associated Hospitalizations:

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).
The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; IA, MI, OH, RI, and UT during the 2012-2013 season; and MI, OH, and UT during the 2013-2014, 2014-15 and 2015-16 seasons.
Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.
Between October 1, 2015 and January 16, 2016, 494 laboratory-confirmed influenza-associated hospitalizations were reported. The overall hospitalization rate was 1.8 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 years (6.1 per 100,000 population), followed by children aged 0-4 years (3.2 per 100,000 population). Among all hospitalizations, 323 (65.4%) were associated with influenza A, 142 (28.7%) with influenza B, 16 (3.2%) with influenza A and B co-infection, and 13 (2.6%) had no virus type information. Among those with influenza A subtype information, 56 (72.7%) were A(H1N1)pdm09 and 21 (27.3%) were A(H3N2) virus.
Clinical findings are preliminary and based on 165 (33.4%) cases with complete medical chart abstraction. The majority (87.1%) of hospitalized adults had at least one reported underlying medical condition; the most commonly reported were metabolic disorders, cardiovascular disease, and obesity. There were 25 hospitalized children with complete medical chart abstraction, 16 (64.0%) had no identified underlying medical conditions. The most commonly reported underlying medical conditions among pediatric patients were asthma, cardiovascular disease, chronic lung disease and neurologic disorders. Among the 9 hospitalized women of childbearing age (15-44 years), 3 were pregnant.
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.

Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
View Interactive Application | View Full Screen | View PowerPoint Presentation
FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancypercentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
View Interactive Application | View Full Screen | View PowerPoint Presentation



Outpatient Illness Surveillance:

Nationwide during week 2, 2.1% 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 at the national baseline of 2.1%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
The increase in the percentage of patient visits for ILI in previous weeks may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 1.0% to 4.1% during week 2. Six regions (Regions 1, 2, 3, 4, 6, and 10) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 2, the following ILI activity levels were calculated:

• Puerto Rico experienced high ILI activity.
• Three states (Arizona, Maryland, and South Carolina) experienced moderate ILI activity.
• New York City and four states (Arkansas, Illinois, New Jersey, and Virginia) experienced low ILI activity.
• 43 states (Alabama, Alaska, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 2, the following influenza activity was reported:

• Widespread influenza activity was reported by three states (Maryland, Massachusetts, and North Carolina).
• Regional influenza activity was reported by Puerto Rico and ten states (Arizona, California, Connecticut, Iowa, Maine, Oregon, Rhode Island, Utah, Virginia, and Washington).
• Local influenza activity was reported by Guam and 12 states (Indiana, Michigan, Minnesota, Nevada, New Hampshire, New Jersey, New Mexico, New York, Oklahoma, Pennsylvania, Texas, and Vermont).
• Sporadic influenza activity was reported by the U.S. Virgin Islands and 24 states (Alaska, Arkansas, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, North Dakota, Ohio, South Carolina, South Dakota, Tennessee, West Virginia, Wisconsin, and Wyoming).
• The District of Columbia and one state (Alabama) reported no influenza activity.

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.

[sharon sanders]

2015-2016 Influenza Season Week 3 ending January 23, 2016

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

During week 3 (January 17-23, 2016), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 3 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.
• Influenza-associated Hospitalizations: A cumulative rate for the season of 2.1 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.2%, which is above the national baseline of 2.1%. Six of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico experienced high ILI activity; three states experienced moderate ILI activity; five states experienced low ILI activity; New York City and 42 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in four states was reported as widespread; Puerto Rico and 14 states reported regional activity; Guam and 12 states reported local activity; and the District of Columbia, the U.S. Virgin Islands and 20 states reported sporadic activity.

National and Regional Summary of Select Surveillance Components

Elevated	4 of 53	5.0%	831	658	125	63	218	181	7
Elevated	1 of 6	3.1%	14	20	0	1	2	3	0
Elevated	1 of 4	2.5%	43	83	5	2	0	9	1
Elevated	1 of 6	0.8%	29	28	25	3	18	4	0
Elevated	1 of 8	7.2%	20	41	24	3	0	47	3
Normal	0 of 6	2.2%	126	47	54	1	19	3	0
Elevated	0 of 5	2.2%	19	35	2	2	6	13	1
Normal	0 of 4	1.7%	19	27	1	3	2	2	0
Normal	0 of 6	3.8%	165	36	1	9	65	3	0
Normal	0 of 4	9.1%	271	271	11	27	78	72	2
Elevated	0 of 4	8.2%	70	70	2	12	28	25	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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

13,517	239,251
680 (5.0%)	5,033 (2.1%)
500 (73.5%)	3,204 (63.7%)
180 (26.5%)	1,829 (36.3%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

865	21,196
242	2,076
195 (80.6%)	1,614 (77.7%)
121 (62.1%)	831 (51.5%)
39 (20.0%)	658 (40.8%)
35 (17.9%)	125 (7.7%)
47 (19.4%)	462 (22.3%)
25 (53.2%)	218 (47.2%)
8 (17.0%)	63 (13.6%)
14 (29.8%)	181 (39.2%)

*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.


View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data |View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 312 influenza viruses [74 A (H1N1)pdm09, 188 A (H3N2), and 50 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [262]

• A (H1N1)pdm09 [74]: All 74 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [188]: All 188 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 92 H3N2 viruses also were antigenically characterized; 91 of 92 (98.9%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [50]

• Yamagata Lineage [25]: All 25 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.

• Victoria Lineage [25]: All 25 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.

Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

143	1 (0.7)	106	0 (0.0)	143	1 (0.7)
192	0 (0.0)	192	0 (0.0)	186	0 (0.0)
104	0 (0.0)	104	0 (0.0)	104	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on January 28, 2016, 7.2% of the deaths occurring during the week ending January 9, 2016 (week 1) were due to P&I. This percentage is below the epidemic threshold of 7.5% for week 1.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 3, 6.8% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.2% for week 3.

View Full Screen | View PowerPoint Presentation

Influenza-Associated Pediatric Mortality:

No influenza-associated pediatric deaths were reported to CDC during week 3. A total of seven influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

View Interactive Application | View Full Screen | View PowerPoint Presentation


Influenza-Associated Hospitalizations:

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).
The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; IA, MI, OH, RI, and UT during the 2012-2013 season; and MI, OH, and UT during the 2013-2014, 2014-15 and 2015-16 seasons.
Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.
Between October 1, 2015 and January 23, 2016, 575 laboratory-confirmed influenza-associated hospitalizations were reported. The overall hospitalization rate was 2.1 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 years (7.0 per 100,000 population), followed by children aged 0-4 years (3.4 per 100,000 population). Among all hospitalizations, 383 (66.6%) were associated with influenza A, 165 (28.7%) with influenza B, 16 (2.8%) with influenza A and B co-infection, and 11 (1.9%) had no virus type information. Among those with influenza A subtype information, 83 (76.1%) were A(H1N1)pdm09 and 26 (23.9%) were A(H3N2) virus.
Clinical findings are preliminary and based on 209 (36.3%) cases with complete medical chart abstraction. The majority (87.7%) of hospitalized adults had at least one reported underlying medical condition; the most commonly reported were metabolic disorders, cardiovascular disease, and obesity. There were 30 hospitalized children with complete medical chart abstraction, 18 (60.0%) had no identified underlying medical conditions. The most commonly reported underlying medical conditions among pediatric patients were asthma, chronic lung disease, cardiovascular disease and neurologic disorders. Among the 13 hospitalized women of childbearing age (15-44 years), 4 were pregnant.
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.

Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
View Interactive Application | View Full Screen | View PowerPoint Presentation
FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancypercentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
View Interactive Application | View Full Screen | View PowerPoint Presentation



Outpatient Illness Surveillance:

Nationwide during week 3, 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 above the national baseline of 2.1%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
The increase in the percentage of patient visits for ILI in previous weeks may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 1.2% to 4.1% during week 3. Six regions (Regions 1, 2, 3, 4, 6, and 10) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 3, the following ILI activity levels were calculated:

• Puerto Rico experienced high ILI activity.
• Three states (Connecticut, Maryland, and South Carolina) experienced moderate ILI activity.
• Five states (Arizona, Illinois, New Jersey, Oklahoma, and Virginia) experienced low ILI activity.
• New York City and 42 states (Alabama, Alaska, Arkansas, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 3, the following influenza activity was reported:

• Widespread influenza activity was reported by four states (California, Maryland, Massachusetts, and North Carolina).
• Regional influenza activity was reported by Puerto Rico and 14 states (Alabama, Arizona, Connecticut, Iowa, Maine, Nevada, New Hampshire, New Mexico, New York, Rhode Island, Texas, Utah, Virginia, and Washington).
• Local influenza activity was reported by Guam and 12 states (Arkansas, Illinois, Indiana, Michigan, Minnesota, New Jersey, North Dakota, Oklahoma, Oregon, Pennsylvania, Vermont, and Wyoming).
• Sporadic influenza activity was reported by the District of Columbia, the U.S. Virgin Islands and 20 states (Alaska, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, Ohio, South Carolina, South Dakota, Tennessee, West Virginia, and Wisconsin).

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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.

[sharon sanders]

2015-2016 Influenza Season Week 4 ending January 30, 2016

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

During week 4 (January 24-30, 2016), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 4 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported.
• Influenza-associated Hospitalizations: A cumulative rate for the season of 2.6 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.2%, which is above the national baseline of 2.1%. Six of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico experienced high ILI activity; two states experienced moderate ILI activity; New York City and 11 states experienced low ILI activity; 37 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and three states was reported as widespread; Guam and 18 states reported regional activity; the District of Columbia and 16 states reported local activity; the U.S. Virgin Islands and 12 states reported sporadic activity; and one state reported no activity.

National and Regional Summary of Select Surveillance Components

Elevated	3 of 53	6.8%	1,134	749	177	83	290	276	9
Elevated	1 of 6	4.2%	23	21	0	1	2	5	0
Elevated	1 of 4	3.7%	63	87	9	2	2	8	1
Elevated	0 of 6	1.0%	43	31	28	4	26	5	0
Elevated	0 of 8	9.3%	89	62	15	4	0	70	3
Normal	0 of 6	3.3%	155	67	92	3	22	6	0
Elevated	1 of 5	3.1%	33	44	3	2	7	18	1
Normal	0 of 4	2.3%	30	29	1	4	2	3	0
Normal	0 of 6	5.1%	216	42	1	11	93	7	0
Normal	0 of 4	10.0%	381	291	25	37	90	107	3
Elevated	0 of 4	10.9%	101	75	4	15	46	47	1

*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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

15,964	258,430
1,085 (6.8%)	6,273 (2.4%)
739 (68.1%)	4,015 (64.0%)
346 (31.9%)	2,258 (36.0%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

1,255	23,304
368	2,709
273 (74.2%)	2,060 (76.0%)
167 (61.2%)	1,134 (55.0%)
55 (20.1%)	749 (36.4%)
51 (18.7%)	177 (8.6%)
95 (25.8%)	649 (24.0%)
36 (37.9%)	290 (44.7%)
15 (15.8%)	83 (12.8%)
44 (46.3%)	276 (42.5%)

*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.


View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
View Chart Data | View Full Screen
View Chart Data |View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 407 influenza viruses [130 A (H1N1)pdm09, 190 A (H3N2), and 87 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [320]

• A (H1N1)pdm09 [130]: All 130 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [190]: All 190 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 93 H3N2 viruses also were antigenically characterized; 92 of 93 (98.9%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [87]

• Yamagata Lineage [52]: All 52 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.

• Victoria Lineage [35]: All 35 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.

Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

229	2 (0.9)	173	0 (0.0)	229	2 (0.9)
225	0 (0.0)	225	0 (0.0)	211	0 (0.0)
130	0 (0.0)	130	0 (0.0)	130	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on February 4, 2016, 7.0% of the deaths occurring during the week ending January 16, 2016 (week 2) were due to P&I. This percentage is below the epidemic threshold of 7.6% for week 2.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 4, 6.8% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.2% for week 4.

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Influenza-Associated Pediatric Mortality:

Two influenza-associated pediatric deaths were reported to CDC during week 4. One death was associated with an influenza A (H1N1)pdm09 virus and occurred during week 2 (the week ending January 16, 2016) and one death was associated with an influenza B virus and occurred during week 4 (the week ending January 30, 2016). A total of nine influenza-associated pediatric deaths have been reported during the 2015-2016 season.
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

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Influenza-Associated Hospitalizations:

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).
The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; IA, MI, OH, RI, and UT during the 2012-2013 season; and MI, OH, and UT during the 2013-2014, 2014-15 and 2015-16 seasons.
Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.
Between October 1, 2015 and January 30, 2016, 723 laboratory-confirmed influenza-associated hospitalizations were reported. The overall hospitalization rate was 2.6 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 years (8.5 per 100,000 population), followed by children aged 0-4 years (3.8 per 100,000 population). Among all hospitalizations, 490 (67.8%) were associated with influenza A, 203 (28.1%) with influenza B, 18 (2.5%) with influenza A and B co-infection, and 12 (1.7%) had no virus type information. Among those with influenza A subtype information, 115 (79.3%) were A(H1N1)pdm09 and 28 (19.3%) were A(H3N2) virus.
Clinical findings are preliminary and based on 274 (37.8%) cases with complete medical chart abstraction. The majority (88.9%) of hospitalized adults had at least one reported underlying medical condition; the most commonly reported were cardiovascular disease, metabolic disorders, and obesity. There were 38 hospitalized children with complete medical chart abstraction, 20 (52.6%) had no identified underlying medical conditions. The most commonly reported underlying medical conditions among pediatric patients were asthma, neurologic disorders and chronic lung disease. Among the 20 hospitalized women of childbearing age (15-44 years), 5 were pregnant.
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.

Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
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FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancypercentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
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Outpatient Illness Surveillance:

Nationwide during week 4, 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 above the national baseline of 2.1%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
The increase in the percentage of patient visits for ILI in weeks 51 and 52 (the weeks ending December 26, 2015 and January 2, 2016) may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 1.1% to 4.7% during week 4. Six regions (Regions 1, 2, 3, 4, 6, and 10) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 4, the following ILI activity levels were calculated:

• Puerto Rico experienced high ILI activity.
• Two states (Arkansas and Connecticut) experienced moderate ILI activity.
• New York City and 11 states (Arizona, Florida, Hawaii, Illinois, Maryland, Nevada, New Jersey, Oklahoma, Pennsylvania, Texas, and Utah) experienced low ILI activity.
• 37 states (Alabama, Alaska, California, Colorado, Delaware, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia.

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 4, the following influenza activity was reported:

• Widespread influenza activity was reported by Puerto Rico and three states (California, Iowa, and Massachusetts).
• Regional influenza activity was reported by Guam and 18 states (Arizona, Connecticut, Indiana, Kentucky, Maine, Maryland, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Rhode Island, Texas, Utah, Vermont, Virginia, and Washington).
• Local influenza activity was reported by the District of Columbia and 16 states (Alabama, Alaska, Arkansas, Colorado, Florida, Idaho, Illinois, Michigan, Minnesota, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, and Wyoming).
• Sporadic influenza activity was reported by the U.S. Virgin Islands and 12 states (Delaware, Georgia, Hawaii, Kansas, Louisiana, Missouri, Montana, Nebraska, South Dakota, Tennessee, West Virginia, and Wisconsin).
• No activity was reported by one state (Mississippi).

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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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.

[sharon sanders]

2015-2016 Influenza Season Week 5 ending February 6, 2016

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

During week 5 (January 31-February 6, 2016), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 5 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.
• Influenza-associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported.
• Influenza-associated Hospitalizations: A cumulative rate for the season of 3.2 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.4%, which is above the national baseline of 2.1%. Seven of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and one state experienced high ILI activity; two states experienced moderate ILI activity; New York City and 8 states experienced low ILI activity; 38 states experienced minimal ILI activity; and the District of Columbia and one state had insufficient data.
• Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and seven states was reported as widespread; Guam and 17 states reported regional activity; 16 states reported local activity; the District of Columbia and 9 states reported sporadic activity; one state reported no activity; and the U.S. Virgin Islands did not report.

National and Regional Summary of Select Surveillance Components

Elevated	4 of 53	9.1%	1,693	838	128	123	372	370	11
Elevated	1 of 6	6.3%	44	23	0	5	3	6	0
Elevated	1 of 4	5.6%	92	89	19	6	3	12	1
Elevated	0 of 6	1.5%	60	33	42	7	27	14	0
Elevated	0 of 8	11.5%	118	75	17	7	1	81	3
Normal	0 of 6	4.9%	316	75	22	3	25	6	2
Elevated	1 of 5	3.7%	41	54	4	3	8	26	1
Normal	0 of 4	2.6%	63	29	0	4	4	6	0
Elevated	0 of 6	7.7%	305	43	1	14	122	10	0
Normal	1 of 4	9.9%	516	340	19	56	112	158	3
Elevated	0 of 4	12.2%	143	77	4	18	67	51	1

*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
§ Includes all 50 states, New York City, the District of Columbia and Puerto Rico
? National data are for current week; regional data are for the most recent three weeks


U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, 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.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.
The results of tests performed by clinical laboratories during the current week are summarized below.

17,175	279,056
1,563 (9.1%)	7,966 (2.9%)
1,135 (72.6%)	5,272 (66.2%)
428 (27.4%)	2,694 (33.8%)

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation The results of tests performed by public health laboratories, as well as the age group distribution of influenza positive tests, during the current week are summarized below.

1,233	26,287
443	3,529
325 (73.4%)	2,664 (75.5%)
255 (78.5%)	1,698 (63.7%)
42 (12.9%)	838 (31.5%)
28 (8.6%)	128 (4.8%)
118 (26.6%)	865 (24.5%)
44 (37.3%)	372 (43.0%)
18 (15.3%)	123 (14.2%)
56 (47.5%)	370 (42.8%)

*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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View Chart Data | View Full Screen
View Chart Data |View Full Screen Influenza Virus Characterization:

CDC characterizes influenza viruses through one or more tests including genome sequencing, hemagglutination inhibition (HI) and/or neutralization assays. These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing influenza vaccines, and to monitor for changes in circulating influenza viruses. Historically, HI data have been used most commonly to assess the similarity between reference viruses and circulating viruses to suggest how well the vaccine may work until such time as vaccine effectiveness estimates are available. During the 2014–2015 season and to date, however, a portion of influenza A (H3N2) viruses do not yield sufficient hemagglutination titers for antigenic characterization by HI. For many of these viruses, CDC performs genetic characterization to determine the genetic group identity of those viruses. In this way, antigenic properties of these viruses can be inferred from viruses within the same genetic group that have been characterized antigenically.
CDC has characterized 483 influenza viruses [180 A (H1N1)pdm09, 216 A (H3N2), and 87 influenza B viruses] collected by U.S. laboratories since October 1, 2015.
Influenza A Virus [396]

• A (H1N1)pdm09 [180]: All 180 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2015-2016 Northern Hemisphere vaccine.

• A (H3N2) [216]: All 216 H3N2 viruses were genetically sequenced and all viruses belonged to genetic groups for which a majority of viruses antigenically characterized were similar to the cell-propagated A/Switzerland/9715293/2013, the influenza A (H3N2) reference virus representing the 2015-2016 Northern Hemisphere vaccine component.
  • A subset of 105 H3N2 viruses also were antigenically characterized; 98 of 105 (93.3%) H3N2 viruses were A/Switzerland/9715293/2013-like by HI testing or neutralization testing.

Influenza B Virus [87]

• Yamagata Lineage [52]: All 52 (100%) B/Yamagata-lineage viruses were antigenically characterized as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere trivalent and quadrivalent influenza vaccines.

• Victoria Lineage [35]: All 35 (100%) B/Victoria-lineage viruses were antigenically characterized as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2015-2016 Northern Hemisphere quadrivalent influenza vaccines.

Antiviral Resistance:

Testing of influenza A(H1N1)pdm09, A(H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using a functional assay. Additional A(H1N1)pdm09 and 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 A(H1N1)pdm09 and A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.

301	2 (0.7)	223	0 (0.0)	301	2 (0.7)
246	0 (0.0)	247	0 (0.0)	233	0 (0.0)
152	0 (0.0)	152	0 (0.0)	152	0 (0.0)

The majority of recently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir, zanamivir, and peramivir; however, rare sporadic instances of oseltamivir-resistant and peramivir-resistant influenza A (H1N1)pdm09 viruses and oseltamivir-resistant influenza A (H3N2) viruses have been detected worldwide. Antiviral treatment as early as possible is recommended 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 athttp://www.cdc.gov/flu/antivirals/index.htm.


Pneumonia and Influenza (P&I) Mortality Surveillance:

Rapid tracking of pneumonia and influenza-associated deaths is done through two systems, the National Center for Health Statistics (NCHS) Mortality Surveillance System and the 122 Cities Mortality Reporting System. NCHS mortality surveillance data are presented by the week the death occurred and P&I percentages are released two weeks after the week of death to allow for collection of enough data to produce a stable P&I percentage. Users of the data should not expect the two systems to produce the same percentages, and the percent P&I deaths from each system should be compared to the corresponding system-specific baselines and thresholds.
NCHS Mortality Surveillance Data:
Based on NCHS mortality surveillance data available on February 11, 2016, 6.9% of the deaths occurring during the week ending January 23, 2016 (week 3) were due to P&I. This percentage is below the epidemic threshold of 7.6% for week 3.
Region and state-specific data are available at http://www.cdc.gov/flu/weekly/nchs.htm.

View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation 122 Cities Mortality Reporting System:
During week 5, 6.2% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.3% for week 5.

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Influenza-Associated Pediatric Mortality:

Two influenza-associated pediatric deaths were reported to CDC during week 5. One death was associated with an influenza A (H1N1)pdm09 virus and one death was associated with an influenza A virus for which no subtyping was performed. Both deaths occurred during week 4 (the week ending January 30, 2016).
A total of 11 influenza-associated pediatric deaths have been reported during the 2015-2016 season from Puerto Rico [1], Chicago [1], and seven states (California [2], Florida [2], Louisiana [1], Michigan [1], Nevada [1], Tennessee [1], and Washington [1]).
Additional data can be found at: http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

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Influenza-Associated Hospitalizations:

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).
The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, and TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; IA, MI, OH, RI, and UT during the 2012-2013 season; and MI, OH, and UT during the 2013-2014, 2014-15 and 2015-16 seasons.
Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.
Between October 1, 2015 and February 6, 2016, 896 laboratory-confirmed influenza-associated hospitalizations were reported. The overall hospitalization rate was 3.2 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 years (10.2 per 100,000 population), followed by children aged 0-4 years (4.5 per 100,000 population), and adults 50-64 years (4.1 per 100,000 population). Among all hospitalizations, 624 (69.6%) were associated with influenza A, 242 (27.0%) with influenza B, 20 (2.2%) with influenza A and B co-infection, and 10 (1.1%) had no virus type information. Among those with influenza A subtype information, 160 (83.8%) were A(H1N1)pdm09 and 29 (15.2%) were A(H3N2) virus.
Clinical findings are preliminary and based on 349 (38.9%) cases with complete medical chart abstraction. The majority (90.7%) of hospitalized adults had at least one reported underlying medical condition; the most commonly reported were cardiovascular disease, metabolic disorders, and obesity. There were 47 hospitalized children with complete medical chart abstraction, 25 (53.2%) had no identified underlying medical conditions. The most commonly reported underlying medical conditions among pediatric patients were asthma, neurologic disorders, cardiovascular disease and chronic lung disease. Among the 29 hospitalized women of childbearing age (15-44 years), 7 were pregnant.
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.

Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
View Interactive Application | View Full Screen | View PowerPoint Presentation
FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancypercentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
View Interactive Application | View Full Screen | View PowerPoint Presentation



Outpatient Illness Surveillance:

Nationwide during week 5, 2.4% 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 above the national baseline of 2.1%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
The increase in the percentage of patient visits for ILI in weeks 51 and 52 (the weeks ending December 26, 2015 and January 2, 2016) may be influenced in part by a reduction in routine healthcare visits during the holidays, as has occurred in previous seasons.
Additional data are available at http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation On a regional level, the percentage of outpatient visits for ILI ranged from 1.1% to 4.5% during week 5. Seven regions (Regions 1, 2, 3, 4, 6, 8, and 10) reported a proportion of outpatient visits for ILI at or above their region-specific baseline levels.


ILINet State Activity Indicator Map:

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 5, the following ILI activity levels were calculated:

• Puerto Rico and one state (Arizona) experienced high ILI activity.
• Two states (Arkansas and Connecticut) experienced moderate ILI activity.
• New York City and eight states (Florida, Illinois, Massachusetts, New Mexico, Oklahoma, Oregon, Texas, and Utah) experienced low ILI activity.
• 38 states (Alabama, Alaska, California, Delaware, Georgia, Hawaii, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming) experienced minimal ILI activity.
• Data were insufficient to calculate an ILI activity level from the District of Columbia and one state (Colorado).

Click on map to launch interactive tool

*This map uses the proportion of outpatient visits to health care providers for ILI 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 are 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.


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 5, the following influenza activity was reported:

• Widespread influenza activity was reported by Puerto Rico and seven states (Arizona, California, Connecticut, Iowa, Kentucky, Massachusetts, and New York).
• Regional influenza activity was reported by Guam and 17 states (Florida, Indiana, Maine, Maryland, Michigan, Minnesota, Nevada, New Hampshire, New Jersey, New Mexico, North Dakota, Pennsylvania, Rhode Island, Texas, Utah, Vermont, and Washington).
• Local influenza activity was reported by 16 states (Alabama, Arkansas, Colorado, Idaho, Illinois, Kansas, Montana, North Carolina, Ohio, Oklahoma, Oregon, South Carolina, Tennessee, Virginia, Wisconsin, and Wyoming).
• Sporadic influenza activity was reported by the District of Columbia and nine states (Alaska, Delaware, Georgia, Hawaii, Louisiana, Missouri, Nebraska, South Dakota, and West Virginia).
• No activity was reported by one state (Mississippi).
• The U.S. Virgin Islands did not report.

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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.

Alabama	Alaska	Arizona	Arkansas	California
Colorado	Connecticut	Delaware	District of Columbia	Florida
Georgia	Hawaii	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine
Maryland	Massachusetts	Michigan	Minnesota	Mississippi
Missouri	Montana	Nebraska	Nevada	New Hampshire
New Jersey	New Mexico	New York	North Carolina	North Dakota
Ohio	Oklahoma	Oregon	Pennsylvania	Rhode Island
South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin
Wyoming	New York City	Virgin Islands	Puerto Rico

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.