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Canada FluWatch Weekly Reports 2017-2018 Season Week 18

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  • #16
    FluWatch report: April 8 to April 14, 2018 (week 15)


    Download the alternative format
    (PDF format, 563 KB, 10 pages)
    Organization:
    Public Health Agency of Canada
    Date published: 2018-04-13

    Related Topics



    Overall Summary

    • Overall influenza activity in Canada continued to decrease, but many parts of the country are still reporting localized activity.
    • Two indicators of influenza activity (influenza-like illness and outbreaks) slightly increased from the previous week.
    • Detections of influenza A were greater than those of influenza B.
    • To date this season, the majority of laboratory-confirmed cases, hospitalizations and deaths with influenza have been among adults 65 years of age and older.
    • For more information on the flu, see our Flu(influenza) web page.
    On this page

    Influenza/Influenza-like Illness Activity (geographic spread)

    In week 15, one region in QC reported widespread activity and 23 regions (BC(1), AB(1), MB(2), ON(7), QC(3), NB(2), NL(3), NS(2), PE(1) and NT(1)) reported localized activity.




    Figure 1 - Map of overall influenza/ILI activity level by province and territory, Canada, week 2018-15

    Note: Influenza/ILI activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates and reported outbreaks. Please refer to detailed definitions at the end of the report. Maps from previous weeks, including any retrospective updates, are available in the mapping feature found in the Weekly Influenza Reports.

    Figure 1 - Text Description Laboratory-Confirmed Influenza Detections

    In week 15, the overall percentage of tests positive for influenza was 15%, a decrease from the previous week. Overall, laboratory detections of influenza are steadily decreasing. Influenza A accounted for 54% of influenza detections in week 15.
    Overall, laboratory detections of influenza are around the average for this time of year. For data on other respiratory virus detections, see the Respiratory Virus Detections in Canada Report.
    Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2017-35 to 2018-15

    The shaded area indicates weeks where the positivity rate was at least 5% and a minimum of 15 positive tests were observed, signalling the period of seasonal influenza activity.

    Figure 2 - Text Description To date this season, 62,062 laboratory-confirmed influenza detections have been reported, of which 56% have been influenza A. Influenza A(H3N2) has been the most common subtype detected this season, representing 91% of subtyped influenza A detections. For more detailed weekly and cumulative influenza data, see the text descriptions for Figures 2 and 3 or the Respiratory Virus Detections in Canada Report.
    Figure 3 - Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2017-35 to 2018-15


    Figure 3 - Text Description To date this season, detailed information on age and type/subtype has been received for 50,204 laboratory-confirmed influenza cases (Table 1). Adults 65 years of age and older represent the largest proportion of cases overall (50%), and among cases of influenza A(H3N2) (59%) and influenza B (48%). Adults aged 20-64 represent 32% of cases overall and 29% of influenza A(H3N2) and 34% of influenza B cases. Although much smaller in numbers (883), the majority of influenza A(H1N1)pdm09 cases are among adults less than 65 years of age, with adults aged 20-64 and children 0-19 years accounting for 54% and 31% of cases respectively.
    0-4 3077 144 551 2382 1452 4529 9%
    5-19 2256 126 536 1594 2525 4781 10%
    20-44 4150 244 1179 2727 2707 6857 14%
    45-64 4558 229 1427 2902 4571 9129 18%
    65+ 14610 140 5314 9156 10298 24908 50%
    Total 28651 883 9007 18761 21553 50204 100%
    Syndromic/Influenza-like Illness Surveillance

    Healthcare Practitioners Sentinel Syndromic Surveillance

    In week 15, 1.5% of visits to healthcare professionals were due to influenza-like illness (ILI); a decrease from the previous week.
    Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2017-35 to 2018-15

    Number of Sentinels Reporting in Week 15: 159
    The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2012-13 to 2016-17

    Figure 4 - Text Description Participatory Syndromic Surveillance

    FluWatchers is a participatory ILI surveillance system that relies on weekly voluntary submissions of syndromic information from Canadians across Canada.
    In week 15, 1,315 participants reported to FluWatchers, of which 2% reported symptoms of cough and fever, and 41% of these consulted a healthcare professional. Among participants who reported cough and fever, 73% reported days missed from work or school, resulting in a combined total of 59 missed days of work or school.
    1315 2% 41% 73% 59
    Influenza Outbreak Surveillance

    In week 15, 44 laboratory-confirmed outbreaks of influenza were reported. Among the reported influenza outbreaks, 31 were reported in long-term care facilities (LTC), three in hospitals, and 10 in other settings. In addition, two ILI outbreaks were reported in schools. Among the 35 outbreaks with influenza type/subtype reported, 22 (63%) were associated with influenza A, 12 (34%) were associated with influenza B and one outbreak (3%) was associated with a mix of influenza A and B.
    To date this season, 1,751 influenza/ILI outbreaks have been reported, of which 1,081 (62%) occurred in LTC facilities. Among the 1,500 outbreaks for which the influenza type/subtype was reported, 825 (55%) were associated with influenza A and 606 (40%) were associated with influenza B, and 69 (5%) were associated with a mix of A and B.
    Figure 5 - Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2017-35 to 2018-15


    Figure 5 - Text Description Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths

    To date this season, 4,835 influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote1. Among the hospitalizations, 3,260 (67%) were associated with influenza A, and 3,190 cases (66%) were in adults 65 years of age or older.
    Additionally, 487 ICU admissions and 265 deaths have been reported to date. Adults aged 65 years of age or older accounted for the greatest proportion of ICU cases (44%), followed by adults aged 20-64 (39%). Adults aged 65 years of age or older accounted the majority of deaths (85%).
    Figure 6 - Cumulative numbers of hospitalizations by age-group reported by participating provinces and territoriesfigure 6 note1, weeks 2017-35 to 2018-15


    Figure 6 - Text Description Figure 6 note 1 Influenza-associated hospitalizations are reported by NL, PE, NS, NB, MB, AB, YT and NT. Only hospitalizations that require intensive medical care are reported by SK.
    Return to figure 6 note1referrer

    Pediatric Influenza Hospitalizations and Deaths

    In week 15, 12 laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Influenza A accounted for 67% of the hospitalizations. Pediatric hospitalizations have been on a general decline since week 07. The number of weekly reported hospitalizations has finally fallen to levels that are near the seven-season average.
    To date this season, 1,034 pediatric hospitalizations have been reported by the IMPACT network, 643 (62%) of which were associated with influenza A. Children 0-23 months accounted for the largest proportion of influenza A hospitalizations (40%). Among the 391 hospitalizations due to influenza B, children 5-9 years accounted for the largest proportion of cases (31%).
    Additionally, 175 ICU admissions and nine deaths have been reported to date. Children aged 0-23 months accounted for the greatest proportion of ICU cases (29%), followed by children aged 5-9 years (26%). Among the ICU cases with available information, 63% were due to influenza A and approximately 47% had no reported previous or concurrent medical conditions. All but one reported deaths were among children over the age of two.
    Figure 7 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by type and age-group reported by the IMPACT network, Canada, weeks 2017-35 to 2018-15


    Figure 7 - Text Description Figure 8 - Number of pediatric hospitalizations (≤16 years of age) with influenza reported by the IMPACT network, by week, Canada, weeks 2017-35 to 2018-15


    Figure 8 - Text Description Figure 8 Footnote 1 The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2016-17
    Return to figure 8 note1referrer

    Influenza Strain Characterizations

    During the 2017-18 influenza season, the National Microbiology Laboratory (NML) has characterized 3,146 influenza viruses [1,377 A(H3N2), 239 A(H1N1)pdm09 and 1,530 B viruses] that were received from Canadian laboratories.
    Antigenic Characterization

    Among influenza viruses characterized by hemagglutination inhibition (HI) assay during the 2017-18 season, most viruses were antigenically similar to the cell-culture propagated reference strains recommended by WHO.
    A/Hong Kong/4801/2014-like 277 Viruses antigenically similar to A/Hong Kong/4801/2014, the A(H3N2) component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent vaccine.
    Reduced titer to A/Hong Kong/4801/2014 79 These A(H3N2) viruses reacted poorly with antisera raised against cell-propagated A/Hong Kong/4801/2014, suggesting some antigenic differences
    A/Michigan/45/2015-like 239 Viruses antigenically similar to A/Michigan/45/2015, the A(H1N1)pdm09 component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent influenza vaccine.
    B/Brisbane/60/2008-like (Victoria lineage) 16 Viruses antigenically similar to B/Brisbane/60/2008.
    B/Brisbane/60/2008 is the influenza B component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent influenza vaccine.
    Reduced titer to B/Brisbane/60/2008
    (Victoria lineage)
    48 These B/Victoria lineage viruses reacted poorly with antisera raised against cell-propagated B/Brisbane/60/2008, suggesting some antigenic differences.
    B/Phuket/3073/2013-like
    (Yamagata lineage)
    1,466 Viruses antigenically similar to B/Phuket/3073/2013, the additional influenza B component of the 2017-18 Northern Hemisphere quadrivalent influenza vaccine.
    Genetic Characterization of A(H3N2) viruses

    During the 2017-18 season, 1,021 A(H3N2) viruses did not grow to sufficient titers for antigenic characterization by HI assay. Therefore, genetic characterization was performed to determine to which genetic group they belong. Sequence analysis showed that 913 A(H3N2) viruses belonged to genetic group 3C.2a, 106 viruses belonged to subclade 3C.2a1 and two viruses belonged to the clade 3C.3a.
    Additionally, of the 356 influenza A(H3N2) viruses that were characterized antigenically as similar to A/Hong Kong/4801/2014, 245 belonged to genetic group 3C.2a and 25 viruses belonged to subclade 3C.2a1. The 79 viruses that showed reduced titer to A/Hong Kong/4801/2014 belonged to genetic clade 3C.3a. Sequencing is pending for the remaining seven isolates.
    A/Hong Kong/4801/2014-like virus belongs to genetic group 3C.2a and is the influenza A/H3N2 component of the 2017-18 Northern Hemisphere influenza vaccine.
    Genetic Characterization of Influenza B viruses

    Among the viruses characterized antigenically as having reduced titer to ferret antisera produced against cell-propagated B/Brisbane/60/2008, sequence analysis showed that 47 viruses had a two amino acid deletion in the HA gene. Sequencing is pending for the remaining virus isolate.

    ...
    https://www.canada.ca/en/public-heal...l-14-2018.html


    "Safety and security don't just happen, they are the result of collective consensus and public investment. We owe our children, the most vulnerable citizens in our society, a life free of violence and fear."
    -Nelson Mandela

    Comment


    • #17
      FluWatch report: April 15, 2018 to April 21, 2018 (Week 16)

      Overall Summary
      • Overall, influenza activity in Canada continued to decrease, but parts of the country are still reporting localized activity.
      • All indicators of influenza activity have either decreased or remained similar to the previous week.
      • Detections of influenza A were greater than those of influenza B.
      • To date this season, the majority of laboratory-confirmed cases, hospitalizations and deaths with influenza have been among adults 65 years of age and older.
      • For more information on the flu, see our Flu(influenza) web page.
      On this page
      Download the alternative format
      (PDF format, 1.7 MB, 11 pages)
      Organization:
      Public Health Agency of Canada
      Date published: 2018-04-27

      Related Topics




      Influenza/Influenza-like Illness Activity (geographic spread)

      In week 16, 14 regions ( ON(7), QC(1), NB(2), NL(2), NS(1) and NT(1)) reported localized activity. Six regions reported no influenza activity.
      Figure 1 - Map of overall influenza/ILI activity level by province and territory, Canada, week 2018-16Note: Influenza/ILI activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates and reported outbreaks. Please refer to detailed definitions at the end of the report. Maps from previous weeks, including any retrospective updates, are available in the mapping feature found in the Weekly Influenza Reports.


      Figure 1 - Text descriptionLaboratory-Confirmed Influenza Detections

      In week 16, the overall percentage of tests positive for influenza was 12%, a decrease from the previous week. Overall, laboratory detections of influenza are steadily decreasing. In week 16, 719 positive influenza tests were reported, down from 955 tests reported in week 15. Influenza A accounted for 57% of influenza detections in week 16.
      Overall, laboratory detections of influenza are around the average for this time of year. For data on other respiratory virus detections, see the Respiratory Virus Detections in Canada Report.
      Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2017-35 to 2018-16

      The shaded area indicates weeks where the positivity rate was at least 5% and a minimum of 15 positive tests were observed, signalling the period of seasonal influenza activity.


      Figure 2 - Text descriptionTo date this season, 62,933 laboratory-confirmed influenza detections have been reported, of which 56% have been influenza A. Influenza A(H3N2) has been the most common subtype detected this season, representing 91% of subtyped influenza A detections. For more detailed weekly and cumulative influenza data, see the text descriptions for Figures 2 and 3 or the Respiratory Virus Detections in Canada Report.
      Figure 3 - Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2017-35 to 2018-16

      Figure 3 - Text descriptionTo date this season, detailed information on age and type/subtype has been received for 50,729 laboratory-confirmed influenza cases (Table 1). Adults 65 years of age and older represent the largest proportion of cases overall (50%), and among cases of influenza A(H3N2) (59%) and influenza B (48%). Adults aged 20-64 represent 32% of cases overall and 29% of influenza A(H3N2) and 34% of influenza B cases. Although much smaller in numbers (898), the majority of influenza A(H1N1)pdm09 cases are among adults less than 65 years of age, with adults aged 20-64 and children 0-19 years accounting for 54% and 30% of cases respectively.
      0-4 3099 148 556 2395 1461 4560 9%
      5-19 2273 125 538 1610 2536 4809 9%
      20-44 4179 251 1183 2745 2732 6911 14%
      45-64 4605 231 1432 2942 4628 9233 18%
      65+ 14791 143 5392 9256 10425 25216 50%
      Total 28947 898 9101 18948 21782 50729 100%
      Table 1 Notes

      Table 1 Note 1UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available
      Return to table 1 note1referrer
      Syndromic/Influenza-like Illness Surveillance

      Healthcare Practitioners Sentinel Syndromic Surveillance

      In week 16, 1.7% of visits to healthcare professionals were due to influenza-like illness (ILI); a decrease from the previous week.
      Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2017-35 to 2018-16

      Number of participants in week 16: 158
      The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2012-13 to 2016-17


      Figure 4 - Text descriptionParticipatory Syndromic Surveillance

      FluWatchers is a participatory ILI surveillance system that relies on weekly voluntary submissions of syndromic information from Canadians across Canada.
      In week 16, 1,314 participants reported to FluWatchers, of which 1% reported symptoms of cough and fever, and 19% of these consulted a healthcare professional. Among participants who reported cough and fever, 88% reported days missed from work or school, resulting in a combined total of 43 missed days of work or school.
      1314 1% 19% 88% 43
      Influenza Outbreak Surveillance

      In week 16, 14 laboratory-confirmed outbreaks of influenza were reported. Among the reported influenza outbreaks, nine were reported in long-term care facilities (LTC), one in a hospital, and four in other settings. In addition, one ILI outbreak was reported in a school. Among the 11 outbreaks with influenza type/subtype reported, eight (73%) were associated with influenza A and three (27%) were associated with influenza B.
      To date this season, 1,767 influenza/ILI outbreaks have been reported, of which 1,091 (62%) occurred in LTC facilities. Among the 1,512 outbreaks for which the influenza type/subtype was reported, 834 (55%) were associated with influenza A and 609 (40%) were associated with influenza B, and 69 (5%) were associated with a mix of A and B.
      Figure 5 - Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2017-35 to 2018-16



      Figure 5 - Text descriptionSevere Outcomes Influenza Surveillance

      Provincial/Territorial Influenza Hospitalizations and Deaths

      To date this season, 4,928 influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote1. Among the hospitalizations, 3,305 (67%) were associated with influenza A, and 3,232 cases (66%) were in adults 65 years of age or older.
      Additionally, 496 ICU admissions and 271 deaths have been reported to date. Adults aged 65 years of age or older accounted for the greatest proportion of ICU cases (44%), followed by adults aged 20-64 (40%). Adults aged 65 years of age or older accounted the majority of deaths (85%).
      Figure 6 - Cumulative numbers of hospitalizations by age-group reported by participating provinces and territoriesfigure 6 note1, weeks 2017-35 to 2018-16



      Figure 6 - Text descriptionFigure 6 note 1Influenza-associated hospitalizations are reported by NL, PE, NS, NB, MB, AB, YT and NT. Only hospitalizations that require intensive medical care are reported by SK.
      Return to figure 6 note1referrer

      Pediatric Influenza Hospitalizations and Deaths

      In week 16, seven laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Influenza A accounted for 57% of the hospitalizations. Pediatric hospitalizations have been on a general decline since week 07. The number of weekly reported hospitalizations has finally fallen to levels that are below the seven-season average.
      To date this season, 1,040 pediatric hospitalizations have been reported by the IMPACT network, 645 (62%) of which were associated with influenza A. Children 0-23 months accounted for the largest proportion of influenza A hospitalizations (40%). Among the 395 hospitalizations due to influenza B, children 5-9 years accounted for the largest proportion of cases (31%).
      Additionally, 177 ICU admissions and nine deaths have been reported to date. Children aged 0-23 months accounted for the greatest proportion of ICU cases (29%), followed by children aged 5-9 years (30%). Among the ICU cases with available information, 25% were due to influenza A and approximately 46% had no reported previous or concurrent medical conditions. All but one reported deaths were among children over the age of two.
      Figure 7 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by type and age-group reported by the IMPACT network, Canada, weeks 2017-35 to 2018-16



      Figure 7 - Text descriptionFigure 8 - Number of pediatric hospitalizations (≤16 years of age) with influenza reported by the IMPACT network, by week, Canada, weeks 2017-35 to 2018-16

      The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2016-17


      Figure 8 - Text descriptionInfluenza Strain Characterizations

      During the 2017-18 influenza season, the National Microbiology Laboratory (NML) has characterized 3,317 influenza viruses [1,420 A(H3N2), 247 A(H1N1)pdm09 and 1,650 B viruses] that were received from Canadian laboratories.
      Antigenic Characterization

      Among influenza viruses characterized by hemagglutination inhibition (HI) assay during the 2017-18 season, most viruses were antigenically similar to the cell-culture propagated reference strains recommended by WHO.
      A/Hong Kong/4801/2014-like 287 Viruses antigenically similar to A/Hong Kong/4801/2014, the A(H3N2) component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent vaccine.
      Reduced titer to A/Hong Kong/4801/2014 82 These A(H3N2) viruses reacted poorly with antisera raised against cell-propagated A/Hong Kong/4801/2014, suggesting some antigenic differences
      A/Michigan/45/2015-like 247 Viruses antigenically similar to A/Michigan/45/2015, the A(H1N1)pdm09 component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent influenza vaccine.
      B/Brisbane/60/2008-like
      (Victoria lineage)
      20 Viruses antigenically similar to B/Brisbane/60/2008.
      B/Brisbane/60/2008 is the influenza B component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent influenza vaccine.
      Reduced titer to B/Brisbane/60/2008
      (Victoria lineage)
      49 These B/Victoria lineage viruses reacted poorly with antisera raised against cell-propagated B/Brisbane/60/2008, suggesting some antigenic differences
      B/Phuket/3073/2013-like
      (Yamagata lineage)
      1581 Viruses antigenically similar to B/Phuket/3073/2013, the additional influenza B component of the 2017-18 Northern Hemisphere quadrivalent influenza vaccine.
      Genetic Characterization of A(H3N2) viruses

      During the 2017-18 season, 1,051 A(H3N2) viruses did not grow to sufficient titers for antigenic characterization by HI assay. Therefore, genetic characterization was performed to determine to which genetic group they belong. Sequence analysis showed that 942 A(H3N2) viruses belonged to genetic group 3C.2a, 107 viruses belonged to subclade 3C.2a1 and two viruses belonged to the clade 3C.3a.
      Additionally, of the 369 influenza A(H3N2) viruses that were characterized antigenically as similar to A/Hong Kong/4801/2014, 251 belonged to genetic group 3C.2a and 26 viruses belonged to subclade 3C.2a1. The 82 viruses that showed reduced titer to A/Hong Kong/4801/2014 belonged to genetic clade 3C.3a. Sequencing is pending for the remaining 10 isolates.
      A/Hong Kong/4801/2014-like virus belongs to genetic group 3C.2a and is the influenza A/H3N2 component of the 2017-18 Northern Hemisphere influenza vaccine.
      Genetic Characterization of Influenza B viruses

      Among the viruses characterized antigenically as having reduced titer to ferret antisera produced against cell-propagated B/Brisbane/60/2008, sequence analysis showed that 48 viruses had a two amino acid deletion in the HA gene. Sequencing is pending for the remaining virus isolate.
      ...

      https://www.canada.ca/en/public-heal...5-21-2018.html


      "Safety and security don't just happen, they are the result of collective consensus and public investment. We owe our children, the most vulnerable citizens in our society, a life free of violence and fear."
      -Nelson Mandela

      Comment


      • #18
        FluWatch report: April 22, 2018 to April 28, 2018 (Week 17)

        Overall Summary

        • Overall, influenza activity in Canada continued to decrease, but parts of the country are still reporting localized activity.
        • The number of regions reporting no influenza activity increased from the previous week.
        • Detections of influenza A were greater than those of influenza B.
        • To date this season, the majority of laboratory-confirmed cases, hospitalizations and deaths with influenza have been among adults 65 years of age and older.
        • For more information on the flu, see our Flu(influenza) web page.
        On this page



        Download the alternative format
        (PDF format, 1.7 MB, 11 pages)
        Organization:
        Public Health Agency of Canada
        Date published: 2018-05-04

        Related Topics






        Influenza/Influenza-like Illness Activity (geographic spread)

        In week 17, 16 regions (BC(1), SK(1), ON(7), NB(3), NL(2), NS(1) and NT(1)) reported localized activity. Nine regions (SK(2), MB(2), NB(1), NS(2) and NU(2)) reported no influenza activity.
        Figure 1 - Map of overall influenza/ILI activity level by province and territory, Canada, week 2018-17 Note: Influenza/ILI activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates and reported outbreaks. Please refer to detailed definitions at the end of the report. Maps from previous weeks, including any retrospective updates, are available in the mapping feature found in the Weekly Influenza Reports.

        Figure 1 - Text description Laboratory-Confirmed Influenza Detections

        In week 17, the percentage of tests positive for influenza was 10%, a decrease from the previous week. Laboratory detections of influenza are steadily decreasing. In week 17, 526 positive influenza tests were reported, down from 719 tests reported in week 16. Influenza A accounted for 57% of influenza detections in week 17.
        Overall, laboratory detections of influenza are around the average for this time of year. For data on other respiratory virus detections, see the Respiratory Virus Detections in Canada Report.
        Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2017-35 to 2018-17

        The shaded area indicates weeks where the positivity rate was at least 5% and a minimum of 15 positive tests were observed, signalling the period of seasonal influenza activity.

        Figure 2 - Text description To date this season, 63,476 laboratory-confirmed influenza detections have been reported, of which 56% have been influenza A. Influenza A(H3N2) has been the most common subtype detected this season, representing 90% of subtyped influenza A detections. For more detailed weekly and cumulative influenza data, see the text descriptions for Figures 2 and 3 or the Respiratory Virus Detections in Canada Report.
        Figure 3 - Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2017-35 to 2018-17
        Figure 3 - Text description To date this season, detailed information on age and type/subtype has been received for 51,076 laboratory-confirmed influenza cases (Table 1). Adults 65 years of age and older represent the largest proportion of cases overall (50%), and among cases of influenza A(H3N2) (59%) and influenza B (48%). Adults aged 20-64 represent 32% of cases overall and 29% of influenza A(H3N2) and 34% of influenza B cases. Although much smaller in numbers (910), the majority of influenza A(H1N1)pdm09 cases are among adults less than 65 years of age, with adults aged 20-64 and children 0-19 years accounting for 54% and 30% of cases respectively.
        0-4 3125 150 557 2418 1475 4600 9%
        5-19 2286 126 539 1621 2544 4830 9%
        20-44 4206 255 1186 2765 2748 6954 14%
        45-64 4633 233 1436 2964 4662 9295 18%
        65+ 14884 146 5426 9312 10513 25397 50%
        Total 29134 910 9144 19080 21942 51076 100%
        Table 1 Notes

        Table 1 Note 1 UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available
        Return to table 1 note1referrer
        Syndromic/Influenza-like Illness Surveillance

        Healthcare Practitioners Sentinel Syndromic Surveillance

        In week 17, 2.0% of visits to healthcare professionals were due to influenza-like illness (ILI).
        Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2017-35 to 2018-17

        Number of participants in week 17: 165
        The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2012-13 to 2016-17

        Figure 4 - Text description Participatory Syndromic Surveillance

        FluWatchers is a participatory ILI surveillance system that relies on weekly voluntary submissions of syndromic information from Canadians across Canada.
        In week 17, 1,319 participants reported to FluWatchers, of which 2% reported symptoms of cough and fever, and 10% of these consulted a healthcare professional. Among participants who reported cough and fever, 80% reported days missed from work or school, resulting in a combined total of 35 missed days of work or school.
        1319 2% 10% 80% 35
        Influenza Outbreak Surveillance

        In week 17, nine laboratory-confirmed outbreaks of influenza were reported. Among the reported influenza outbreaks, six were reported in long-term care facilities (LTC) and three in other settings. In addition, one ILI outbreak was reported in a school. Among the seven outbreaks with influenza type/subtype reported, five (71%) were associated with influenza B and two (29%) were associated with influenza A.
        To date this season, 1,778 influenza/ILI outbreaks have been reported, of which 1,098 (62%) occurred in LTC facilities. Among the 1,520 outbreaks for which the influenza type/subtype was reported, 836 (55%) were associated with influenza A and 615 (40%) were associated with influenza B, and 69 (5%) were associated with a mix of A and B.
        Figure 5 - Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2017-35 to 2018-17


        Figure 5 - Text description Severe Outcomes Influenza Surveillance

        Provincial/Territorial Influenza Hospitalizations and Deaths

        To date this season, 5,004 influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote1. Among the hospitalizations, 3,337 (67%) were associated with influenza A, and 3,275 cases (65%) were in adults 65 years of age or older.
        Additionally, 504 ICU admissions and 278 deaths have been reported to date. Adults aged 65 years of age or older accounted for the greatest proportion of ICU cases (44%), followed by adults aged 20-64 (40%). Adults aged 65 years of age or older accounted the majority of deaths (85%).
        Figure 6 - Cumulative numbers of hospitalizations by age-group reported by participating provinces and territoriesfigure 6 note1, weeks 2017-35 to 2018-17


        Figure 6 - Text description Figure 6 note 1 Influenza-associated hospitalizations are reported by NL, PE, NS, NB, MB, AB, YT and NT. Only hospitalizations that require intensive medical care are reported by SK.
        Return to figure 6 note1referrer

        Pediatric Influenza Hospitalizations and Deaths

        In week 17, 12 laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Influenza A accounted for 67% of the hospitalizations. Pediatric hospitalizations have been on a general decline since week 07. The number of weekly reported hospitalizations are below the seven-season average.
        To date this season, 1,054 pediatric hospitalizations have been reported by the IMPACT network, 654 (62%) of which were associated with influenza A. Children 0-23 months accounted for the largest proportion of influenza A hospitalizations (39%). Among the 400 hospitalizations due to influenza B, children 5-9 years accounted for the largest proportion of cases (31%).
        Additionally, 179 ICU admissions and nine deaths have been reported to date. Children aged 0-23 months accounted for the greatest proportion of ICU cases (30%), followed by children aged 5-9 years (26%). Among the ICU cases with available information, 63% were due to influenza A and approximately 47% had no reported previous or concurrent medical conditions. All but one reported deaths were among children over the age of two.
        Figure 7 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by type and age-group reported by the IMPACT network, Canada, weeks 2017-35 to 2018-17


        Figure 7 - Text description Figure 8 - Number of pediatric hospitalizations (≤16 years of age) with influenza reported by the IMPACT network, by week, Canada, weeks 2017-35 to 2018-17

        The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2016-17

        Figure 8 - Text description Influenza Strain Characterizations

        During the 2017-18 influenza season, the National Microbiology Laboratory (NML) has characterized 3,358 influenza viruses [1,426 A(H3N2), 252 A(H1N1)pdm09 and 1,680 B viruses] that were received from Canadian laboratories.
        Antigenic Characterization

        Among influenza viruses characterized by hemagglutination inhibition (HI) assay during the 2017-18 season, most viruses were antigenically similar to the cell-culture propagated reference strains recommended by WHO.
        A/Hong Kong/4801/2014-like 291 Viruses antigenically similar to A/Hong Kong/4801/2014, the A(H3N2) component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent vaccine.
        Reduced titer to A/Hong Kong/4801/2014 84 These A(H3N2) viruses reacted poorly with antisera raised against cell-propagated A/Hong Kong/4801/2014, suggesting some antigenic differences.
        A/Michigan/45/2015-like 252 Viruses antigenically similar to A/Michigan/45/2015, the A(H1N1)pdm09 component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent influenza vaccine.
        B/Brisbane/60/2008-like
        (Victoria lineage)
        20 Viruses antigenically similar to B/Brisbane/60/2008. B/Brisbane/60/2008 is the influenza B component of the 2017-18 Northern Hemisphere’s trivalent and quadrivalent influenza vaccine.
        Reduced titer to B/Brisbane/60/2008
        (Victoria lineage)
        51 These B/Victoria lineage viruses reacted poorly with antisera raised against cell-propagated B/Brisbane/60/2008, suggesting some antigenic differences.
        B/Phuket/3073/2013-like
        (Yamagata lineage)
        1609 Viruses antigenically similar to B/Phuket/3073/2013, the additional influenza B component of the 2017-18 Northern Hemisphere quadrivalent influenza vaccine.
        Genetic Characterization of A(H3N2) viruses

        During the 2017-18 season, 1,051 A(H3N2) viruses did not grow to sufficient titers for antigenic characterization by HI assay. Therefore, genetic characterization was performed to determine to which genetic group they belong. Sequence analysis showed that 942 A(H3N2) viruses belonged to genetic group 3C.2a, 107 viruses belonged to subclade 3C.2a1 and two viruses belonged to the clade 3C.3a.
        Additionally, of the 291 influenza A(H3N2) viruses that were characterized antigenically as similar to A/Hong Kong/4801/2014, 265 belonged to genetic group 3C.2a and 26 viruses belonged to subclade 3C.2a1. The 84 viruses that showed reduced titer to A/Hong Kong/4801/2014 belonged to genetic clade 3C.3a.
        A/Hong Kong/4801/2014-like virus belongs to genetic group 3C.2a and is the influenza A/H3N2 component of the 2017-18 Northern Hemisphere influenza vaccine.
        Genetic Characterization of Influenza B viruses

        Among the viruses characterized antigenically as having reduced titer to ferret antisera produced against cell-propagated B/Brisbane/60/2008, sequence analysis showed that 49 viruses had a two amino acid deletion in the HA gene. Sequencing is pending for the remaining two virus isolates.
        ...

        https://www.canada.ca/en/public-heal...2-28-2018.html


        "Safety and security don't just happen, they are the result of collective consensus and public investment. We owe our children, the most vulnerable citizens in our society, a life free of violence and fear."
        -Nelson Mandela

        Comment


        • #19
          FluWatch report: April 29, 2018 to May 5, 2018 (Week 18)

          Overall Summary

          • Overall, influenza activity in Canada continued to decrease, but parts of Central and Eastern Canada are still reporting localized activity.
          • Many indicators of influenza activity are either near or below average for this time of year.
          • Detections of influenza A were greater than those of influenza B.
          • To date this season, the majority of laboratory-confirmed cases, hospitalizations and deaths with influenza have been among adults 65 years of age and older.
          • For more information on the flu, see our Flu(influenza) web page.
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          Organization:
          Public Health Agency of Canada
          Date published: 2018-05-11

          Related Topics






          Influenza/Influenza-like Illness Activity (geographic spread)

          In week 18, 13 regions (MB(1), ON(6), QC(2), NB(1), NL(2) and PE(1)) reported localized activity. Eight regions (MB(2), NB(2), NS(1), YK(1) and NU(2)) reported no influenza activity.
          Figure 1 - Map of overall influenza/ILI activity level by province and territory, Canada, week 2018-18 Note: Influenza/ILI activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates and reported outbreaks. Please refer to detailed definitions at the end of the report. Maps from previous weeks, including any retrospective updates, are available in the mapping feature found in the Weekly Influenza Reports.

          Figure 1 - Text description Laboratory-Confirmed Influenza Detections

          In week 18, the percentage of tests positive for influenza was 8%, a decrease from the previous week. Laboratory detections of influenza are steadily decreasing. In week 18, 367 positive influenza tests were reported, down from 526 tests reported in week 17. Influenza A accounted for 66% of influenza detections in week 18.
          Overall, laboratory detections of influenza are below average for this time of year. For data on other respiratory virus detections, see the Respiratory Virus Detections in Canada Report. Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2017-35 to 2018-18

          The shaded area indicates weeks where the positivity rate was at least 5% and a minimum of 15 positive tests were observed, signalling the period of seasonal influenza activity.

          Figure 2 - Text description To date this season, 63,853 laboratory-confirmed influenza detections have been reported, of which 56% have been influenza A. Influenza A(H3N2) has been the most common subtype detected this season, representing 90% of subtyped influenza A detections. For more detailed weekly and cumulative influenza data, see the text descriptions for Figures 2 and 3 or the Respiratory Virus Detections in Canada Report.
          Figure 3 - Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2017-35 to 2018-18
          Figure 3 - Text description To date this season, detailed information on age and type/subtype has been received for 51,313 laboratory-confirmed influenza cases (Table 1). Adults 65 years of age and older represent the largest proportion of cases overall (50%), and among cases of influenza A(H3N2) (59%) and influenza B (48%). Adults aged 20-64 represent 32% of cases overall and 29% of influenza A(H3N2) and 34% of influenza B cases. Although much smaller in numbers (933), the majority of influenza A(H1N1)pdm09 cases are among adults less than 65 years of age, with adults aged 20-64 and children 0-19 years accounting for 53% and 31% of cases respectively.
          0-4 3139 157 557 2425 1477 4616 9%
          5-19 2298 129 539 1630 2548 4846 9%
          20-44 4226 256 1191 2779 2760 6986 14%
          45-64 4654 236 1442 2976 4677 9331 18%
          65+ 14975 155 5461 9359 10559 25534 50%
          Total 29292 933 9190 19169 22021 51313 100%
          Table 1 Notes

          Table 1 Note 1 UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available
          Return to table 1 note1referrer
          Syndromic/Influenza-like Illness Surveillance

          Healthcare Practitioners Sentinel Syndromic Surveillance

          In week 18, 1.5% of visits to healthcare professionals were due to influenza-like illness (ILI).
          Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2017-35 to 2018-18

          Number of participants in week 18: 166
          The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2012-13 to 2016-17

          Figure 4 - Text description Participatory Syndromic Surveillance

          FluWatchers is a participatory ILI surveillance system that relies on weekly voluntary submissions of syndromic information from Canadians across Canada.
          In week 18, 1,270 participants reported to FluWatchers, of which 1% reported symptoms of cough and fever, and 0% of these consulted a healthcare professional. Among participants who reported cough and fever, 75% reported days missed from work or school, resulting in a combined total of 36 missed days of work or school. FluWatchers surveillance has ended for the 2017-18 season.
          1270 1% 0% 75% 36
          Influenza Outbreak Surveillance

          In week 18, 11 laboratory-confirmed outbreaks of influenza were reported. Among the reported influenza outbreaks, four were reported in long-term care facilities (LTC), three in hospitals and four in other settings. Among the ten outbreaks with influenza type/subtype reported, seven (70%) were associated with influenza A, two (20%) were associated with influenza B and one outbreak was associated with a mix or influenza A and B (10%).
          To date this season, 1,789 influenza/ILI outbreaks have been reported, of which 1,102 (62%) occurred in LTC facilities. Among the 1,530 outbreaks for which the influenza type/subtype was reported, 843 (55%) were associated with influenza A and 617 (40%) were associated with influenza B, and 70 (5%) were associated with a mix of A and B.
          Figure 5 - Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2017-35 to 2018-18


          Figure 5 - Text description Severe Outcomes Influenza Surveillance

          Provincial/Territorial Influenza Hospitalizations and Deaths

          To date this season, 5,059 influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote1. Among the hospitalizations, 3,373 (67%) were associated with influenza A, and 3,308 cases (65%) were in adults 65 years of age or older.
          Additionally, 508 ICU admissions and 290 deaths have been reported to date. Adults aged 65 years of age or older accounted for the greatest proportion of ICU cases (44%), followed by adults aged 20-64 (40%). Adults aged 65 years of age or older accounted the majority of deaths (86%).
          Figure 6 - Cumulative numbers of hospitalizations by age-group reported by participating provinces and territoriesfigure 6 note1, weeks 2017-35 to 2018-18


          Figure 6 - Text description Figure 6 note 1 Influenza-associated hospitalizations are reported by NL, PE, NS, NB, MB, AB, YT and NT. Only hospitalizations that require intensive medical care are reported by SK.
          Return to figure 6 note1referrer

          Pediatric Influenza Hospitalizations and Deaths

          In week 18, 10 laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Influenza A accounted for 80% of the hospitalizations. Pediatric hospitalizations have been on a general decline since week 07. The number of weekly reported hospitalizations are below the seven-season average.
          To date this season, 1,066 pediatric hospitalizations have been reported by the IMPACT network, 663 (62%) of which were associated with influenza A. Children 0-23 months accounted for the largest proportion of influenza A hospitalizations (39%). Among the 403 hospitalizations due to influenza B, children 5-9 years accounted for the largest proportion of cases (31%).
          Additionally, 183 ICU admissions and nine deaths have been reported to date. Children aged 0-23 months accounted for the greatest proportion of ICU cases (31%), followed by children aged 5-9 years (26%). Among the ICU cases with available information, 63% were due to influenza A and approximately 46% had no reported previous or concurrent medical conditions. All but one reported deaths were among children over the age of two.
          Figure 7 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by type and age-group reported by the IMPACT network, Canada, weeks 2017-35 to 2018-18


          Figure 7 - Text description Figure 8 - Number of pediatric hospitalizations (≤16 years of age) with influenza reported by the IMPACT network, by week, Canada, weeks 2017-35 to 2018-18

          The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2016-18

          Figure 8 - Text description Influenza Strain Characterizations

          During the 2017-18 influenza season, the National Microbiology Laboratory (NML) has characterized 3,571 influenza viruses [1,478 A(H3N2), 287 A(H1N1)pdm09 and 1,806 B viruses] that were received from Canadian laboratories.
          Antigenic Characterization

          Among influenza viruses characterized by hemagglutination inhibition (HI) assay during the 2017-18 season, most viruses were antigenically similar to the cell-culture propagated reference strains recommended by WHO.
          A/Hong Kong/4801/2014-like 296 Viruses antigenically similar to A/Hong Kong/4801/2014, the A(H3N2) component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent vaccine.
          Reduced titer to A/Hong Kong/4801/2014 88 These A(H3N2) viruses reacted poorly with antisera raised against cell-propagated A/Hong Kong/4801/2014, suggesting some antigenic differences.
          A/Michigan/45/2015-like 287 Viruses antigenically similar to A/Michigan/45/2015, the A(H1N1)pdm09 component of the 2017-18 Northern Hemisphere's trivalent and quadrivalent influenza vaccine.
          B/Brisbane/60/2008-like
          (Victoria lineage)
          24 Viruses antigenically similar to B/Brisbane/60/2008. B/Brisbane/60/2008 is the influenza B component of the 2017-18 Northern Hemisphere’s trivalent and quadrivalent influenza vaccine.
          Reduced titer to B/Brisbane/60/2008
          (Victoria lineage)
          54 These B/Victoria lineage viruses reacted poorly with antisera raised against cell-propagated B/Brisbane/60/2008, suggesting some antigenic differences.
          B/Phuket/3073/2013-like
          (Yamagata lineage)
          1728 Viruses antigenically similar to B/Phuket/3073/2013, the additional influenza B component of the 2017-18 Northern Hemisphere quadrivalent influenza vaccine.
          Genetic Characterization of A(H3N2) viruses

          During the 2017-18 season, 1,094 A(H3N2) viruses did not grow to sufficient titers for antigenic characterization by HI assay. Therefore, genetic characterization was performed to determine to which genetic group they belong. Sequence analysis showed that 981 A(H3N2) viruses belonged to genetic group 3C.2a, 111 viruses belonged to subclade 3C.2a1 and two viruses belonged to the clade 3C.3a.
          Additionally, of the 384 influenza A(H3N2) viruses that were antigenically characterized , 267 belonged to genetic group 3C.2a and 26 viruses belonged to subclade 3C.2a1. The 88 viruses that showed reduced titer to A/Hong Kong/4801/2014 belonged to genetic clade 3C.3a. Sequencing is pending for the remaining three virus isolates.
          A/Hong Kong/4801/2014-like virus belongs to genetic group 3C.2a and is the influenza A/H3N2 component of the 2017-18 Northern Hemisphere influenza vaccine.
          Genetic Characterization of Influenza B viruses

          Of the 78 influenza B viruses characterized as B/ B/Brisbane/60/2008-like, 24 viruses were antigenically similar to the vaccine strain B/Brisbane/60/2008. Among the viruses characterized antigenically as having reduced titer to ferret antisera produced against cell-propagated B/Brisbane/60/2008, sequence analysis showed that 49 viruses had a two amino acid deletion in the HA gene. Sequencing is pending for the remaining five virus isolates.
          ...

          https://www.canada.ca/en/public-heal...ay-5-2018.html


          "Safety and security don't just happen, they are the result of collective consensus and public investment. We owe our children, the most vulnerable citizens in our society, a life free of violence and fear."
          -Nelson Mandela

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