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Weekly #US #Influenza #Surveillance #Report - 2016-17 Season, Wk 8 ending Feb. 25 ‘17 (@CDCgov, summary)

 

Title: Weekly #US #Influenza #Surveillance #Report - 2016-17 Season, Wk 8 ending Feb. 25 ‘17.

Subject: Seasonal Human Influenza, current epidemiological situation in the US.

Source: US Centers for Disease Control and Prevention (CDC), FluView, full page: (LINK). Summary.

Code: [     ]

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Weekly U.S. Influenza Surveillance Report - 2016-2017 Influenza Season Week 8 ending February 25, 2017

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|-- Full report also available as PDF --|

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

 

Synopsis

    • During week 8 (February 19-25 2017), influenza activity remained elevated in the United States.
  • Viral Surveillance:
    • The most frequently identified influenza virus subtype reported by public health laboratories during week 8 was influenza A (H3).
    • The percentage of respiratory specimens testing positive for influenza in clinical laboratories remained elevated.
  • Pneumonia and Influenza Mortality:
    • The proportion of deaths attributed to pneumonia and influenza (P&I) was above the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
  • Influenza-associated Pediatric Deaths:
    • Six influenza-associated pediatric deaths were reported.
  • Influenza-associated Hospitalizations:
    • A cumulative rate for the season of 39.4 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 4.8%, which is above the national baseline of 2.2%.
    • All 10 regions reported ILI at or above their region-specific baseline levels. 27 states experienced high ILI activity; four states experienced moderate ILI activity; New York City, Puerto Rico and six states experienced low ILI activity; 13 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 43 states was reported as widespread; Guam and five states reported regional activity; the District of Columbia and two states reported local activity; and the U.S. Virgin Islands reported sporadic activity.

 

National and Regional Summary of Select Surveillance Components

[HHS Surveillance Regions* - Data for current week: Out-patient ILI† - Number of jurisdictions reporting regional or widespread activity§ - % respiratory specimens positive for flu in clinical laboratories‡ – Data cumulative since October 2, 2016 (week 40): A(H1N1)pdm09 - A (H3) - A (Subtyping not Performed) - B Victoria lineage - B Yamagata lineage - B lineage not performed - Pediatric Deaths]

Influenza test results from public health laboratories only

  • Nation – Elevated - 50 of 54 - 24.2% – 534 - 21,303 – 330 – 707 - 1,067 – 576 – 40
    • Region 1 – Elevated - 6 of 6 - 26.7% – 27 - 1,483 – 0 – 23 – 63 – 60 – 0
    • Region 2 – Elevated - 3 of 4 - 29.9% – 2 - 1,073 – 21 – 28 – 22 – 68 – 6
    • Region 3 – Elevated - 5 of 6 - 30.9% – 46 - 2,892 – 13 – 70 – 185 – 69 – 5
    • Region 4 – Elevated - 8 of 8 - 21.7% – 73 - 1,970 – 43 – 141 – 75 – 174 – 10
    • Region 5 – Elevated - 6 of 6 - 29.2% – 72 - 3,188 – 35 – 230 – 255 – 58 – 6
    • Region 6 – Elevated - 5 of 5 - 25.1% – 56 – 957 – 4 – 21 – 76 – 52 – 3
    • Region 7 – Elevated – 4 of 4 - 21.6% – 19 – 930 – 62 – 67 – 83 – 16 – 4
    • Region 8 – Elevated - 6 of 6 - 16.2% – 71 - 2,054 – 23 – 65 – 239 – 10 – 0
    • Region 9 – Elevated - 4 of 5 - 11.7% – 152 - 4,757 – 119 – 48 – 51 – 41 – 5
    • Region 10 – Elevated - 3 of 4 - 13.2% – 16 - 1,999 – 10 – 14 – 18 – 28 – 1

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{*} 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, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands

{‡} 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 for 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/fluportaldashboard.html and http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.

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

[Week 8 - Data Cumulative since October 2, 2016 (Week 40)]

  • No. of specimens tested - 35,124 - 535,763
    • No. of positive specimens (%) - 8,515 (24.2%) - 70,953 (13.2%)
      • Positive specimens by type:
        • Influenza A - 6,300 (74.0%) - 59,631 (84.0%)
        • Influenza B - 2,215 (26.0%) - 11,322 (16.0%)

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View National and Regional Level Graphs and Data

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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.

[Week 8 - Data Cumulative since October 2, 2016 (Week 40)]

  • No. of specimens tested - 1,924 - 52,547
    • No. of positive specimens* - 1,070 - 24,517
      • Positive specimens by type/subtype:
        • Influenza A - 884 (82.6%) - 22,167 (90.4%)
          • A(H1N1)pmd09 - 26 (2.9%) - 534 (2.4%)
          • H3 - 804 (91.0%) - 21,303 (96.1%)
          • Subtyping not performed - 54 (6.1%) - 330 (1.5%)
        • Influenza B - 186 (17.4%) - 2,350 (9.6%)
          • Yamagata lineage - 82 (44.1%) - 1,067 (45.4%)
          • Victoria lineage - 27 (14.5%) - 707 (30.1%)
          • Lineage not performed - 77 (41.4%) - 576 (24.5%)

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{*} 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 National and Regional Level Graphs and Data

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Antigenic Characterization

CDC has antigenically characterized 766 influenza viruses [112 influenza A (H1N1)pdm09, 399 influenza A (H3N2), and 255 influenza B viruses] collected by U.S. laboratories since October 1, 2016.

Influenza A Virus [511]

  • A (H1N1)pdm09 [112]:
    • All 112 (100%) influenza A (H1N1)pdm09 viruses were antigenically characterized using ferret post-infection antisera as A/California/7/2009-like, the influenza A (H1N1) component of the 2016-2017 Northern Hemisphere vaccine.
  • A (H3N2) [399]:
    • 387 of 399 (97.0%) influenza A (H3N2) viruses were antigenically characterized as A/Hong Kong/4801/2014-like, a virus that belongs in genetic group 3C.2a and is the influenza A (H3N2) component of the 2016-2017 Northern Hemisphere vaccine, by HI testing or neutralization testing.
    • Among the viruses which reacted poorly with ferret antisera raised against A/Hong Kong/4801/2014-like viruses, 9 out of 12 (75%) are more closely related to A/Switzerland/9715293/2013, a virus belonging to genetic group 3C.3a.

Influenza B Virus [255]

  • Victoria Lineage [134]:
    • 123 of 134 (91.8%) B/Victoria-lineage viruses were antigenically characterized using ferret post-infection antisera as B/Brisbane/60/2008-like, which is included as an influenza B component of the 2016-2017 Northern Hemisphere trivalent and quadrivalent influenza vaccines.
  • Yamagata Lineage [121]:
    • All 121 (100%) B/Yamagata-lineage viruses were antigenically characterized using ferret post-infection antisera as B/Phuket/3073/2013-like, which is included as an influenza B component of the 2016-2017 Northern Hemisphere quadrivalent influenza vaccines.

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Keywords: USA; US CDC; Updates; Seasonal Influenza.

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