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Canada FluWatch Weekly Reports 2018-2019 Season Week 13

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  • #16
    FluWatch report: March 10, 2019 to March 16, 2019 (week 11)


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    (PDF format, 896 KB, 9 pages)
    Organization: Public Health Agency of Canada
    Date published: 2019-03-22

    Related Topics



    Overall Summary

    • Influenza activity continues to be reported in almost all regions in Canada but is circulating at higher levels in eastern regions.
    • Detections of influenza A(H3N2) have been steadily increasing since mid-January and accounted for 64% of subtyped influenza A detections this week; however, influenza A(H1N1)pdm09 remains the predominant subtype to date this season.
    • There is currently very little influenza B circulation compared to previous seasons.
    • The World Health Organization (WHO) has released the recommended composition of the influenza vaccine for use in the 2019-2020 northern hemisphere influenza season. The recommended strain was changed for each of the A(H1N1)pdm09 and A(H3N2) components compared to this year's vaccine.


    On this page

    Influenza/ILI Activity (geographic spread)

    During week 11, the following influenza activity levels were reported (Figure 1):
    • 19 regions reported localized activity: in Alta.(2), Man.(1), Ont.(6), Que.(3), N.S.(4), N.B.(1), and N.L.(2).
    • 29 regions reported sporadic activity: in B.C.(5), Alta.(3), Man.(2), Ont.(1), Que.(3), N.B.(6), N.L.(2), P.E.I.(1), Nvt.(1), Y.T.(1) and N.W.T.(1)
    • Five regions: in Man.(2), Nvt.(2) and N.W.T.(1) reported no activity.



    Figure 1 Map of overall influenza/ILI activity by province and territory, Canada, week 2019-11


    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 11, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
    • The percentage of tests positive for influenza continued to increase slightly to 21.4%.
    • A total 1,721 laboratory detections of influenza were reported, of which 95% were influenza A.
    • Influenza A(H3N2) accounted for 64% of subtyped influenza A detections.
    • Detections of influenza A(H3N2) have been steadily increasing, from 93 detections in week 4 (mid-January) to 339 this week.
    To date this season, 37,610 laboratory-confirmed influenza detections have been reported:
    • 98% have been influenza A.
    • Among the 12,926 influenza A viruses subtyped, 83% have been A(H1N1)pdm09.
    • Influenza B often circulates later in the season in Canada (Feb-Apr). Fewer influenza B detections have been reported this season compared to recent seasons at this time of year.
    To date this season, detailed information on age and type/subtype has been received for 29,558 laboratory-confirmed influenza cases (Table 1):
    • 84% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
    • 59% of all influenza A(H3N2) detections have been reported in adults 65 years of age and older.
    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 2 Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2018-35 to 2019-11


    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 equivalent Figure 3 Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-11


    Figure 3 - Text equivalent
    0-4 5965 1632 91 4242 95 6060 21%
    5-19 4255 1348 175 2732 134 4389 15%
    20-44 5709 1845 268 3596 98 5807 20%
    45-64 5722 1774 236 3712 67 5789 20%
    65+ 7344 1288 1097 4959 169 7513 25%
    Total 28995 7887 1867 19241 563 29558 100%
    Table 1 - Note 1 UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available.
    Return to Table 1 - Note1
    Syndromic/Influenza-like Illness Surveillance

    Healthcare Professionals Sentinel Syndromic Surveillance

    In week 11, 0.7% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4). The percentage of visits for ILI is low compared to previous seasons.
    Figure 4 Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2019-11

    Number of Sentinels Reporting in Week 11: 75

    The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2013-14 to 2017-18
    Figure 4 - Text equivalent Participatory Syndromic Surveillance

    In week 11, 2,066 participants reported to FluWatchers, of which 54 (2.7%) reported symptoms of cough and fever (Figure 5).
    Among the 54 participants who reported fever and cough:
    • 13% consulted a healthcare professional;
    • 75% reported days missed from work or school, resulting in a combined total of 124 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-11

    Number of Participants Reporting in Week 11: 2,066

    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 11, 29 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (16), acute care facilities (2) and other settings (11). Two new ILI outbreaks (one in a school and one in a LTCF) were also reported in week 11.
    To date this season, 586 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 346 (59%) outbreaks were in LTCF, 29 were in schools, 86 in acute care facilities, and 125 were in other settings.
    • Among the 523 outbreaks for which the influenza type was available, 98% (512) were associated with influenza A.
    • Among the 221 outbreaks for which the influenza A subtype was available, 55% (121) were associated with influenza A(H1N1)pdm09;
    To date this season, 121 ILI outbreaks have been reported; 65 occurred in LTCF, 52 in schools, and four in acute care facilities.
    Figure 6 Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-11


    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 2,474 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.0% (2,449) were associated with influenza A
    • The highest estimated rate of hospitalization is among adults over 65 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 446 ICU admissions and 109 deaths have been reported.
      • 42% (189) of reported ICU admissions were in adults aged 45-64 years.
      • All but four ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 343 9 73.95
    5-19 204 8 15.28
    20-44 311 1 10.97
    45-64 670 2 30.88
    65+ 921 5 76.11
    Total 2449 25
    % 99.0% 1.0%
    Table 2 - Note 1 Influenza-associated hospitalizations are reported by Alberta, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Prince Edward Island and Yukon. Only hospitalizations that require intensive medical care are reported by Saskatchewan. The cumulative rate of hospitalizations is calculated using the total population by age-group in participating provinces and territories.
    Return to Table 2 - Note1
    Pediatric Influenza Hospitalizations and Deaths

    In week 11, 37 pediatric (≤16 years of age) hospitalizations with influenza have been reported by the Immunization Monitoring Program Active (IMPACT) network (Figure 7).
    To date this season, 1,046 pediatric hospitalizations have been reported (Figure 8):
    • 67% of cases were in children under 5 years of age.
    • 97% (1,017) of cases have been associated with influenza A.
    • Among the 316 cases for which the influenza subtype was available, 286 (91%) were associated with A(H1N1)pdm09.
    To date this season, 188 ICU admissions, and 10 deaths have been reported.
    • 61% (114) of ICU admissions were in children under 5 years of age.
    • All but two of the ICU admissions have been associated with influenza A.
    • 80% (8) of deaths occurred in children 2 to 4 years of age.
    • All deaths have been associated with influenza A.
    Figure 7 Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2019-11


    The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
    Figure 7 - Text equivalent Figure 8 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, weeks 2018-35 to 2019-11


    Figure 8 - Text equivalent Adult Influenza Hospitalizations and Deaths

    Surveillance of laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network began on November 1st for the 2018-19 season.
    To date this season, 729 hospitalizations, 88 ICU admissions and 32 deaths have been reported (Figure 9):
    • 676 (93%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (59%) compared to adults <65 years of age (41%).
    • 86% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 82% of hospitalized cases.
    Figure 9 - Cumulative numbers of adult hospitalizations (>20 years of age) with influenza by age-group reported by CIRN, Canada, 2018-19, weeks 2018-44 to 2019-11


    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,622 influenza viruses (212 A(H3N2), 1,375 A(H1N1) and 35 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    102 influenza A(H3N2) viruses did not grow to sufficient hemagglutination titer for antigenic characterization by hemagglutination inhibition (HI) assay. Therefore, NML has performed genetic characterization to determine the genetic group identity of these viruses.
    Sequence analysis of the HA gene of the viruses showed that:
    • 17 viruses belonged to genetic group 3C.2a.
    • 82 viruses belonged to subclade 3C.2a1.
    • Two viruses belonged to 3C.3a.
    • One isolate could not be sequenced.
    A/Singapore/INFIMH-16-0019/2016-like virus belongs to genetic group 3C.2a1 and is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
    Antigenic Characterization:

    Influenza A (H3N2):
    • 74 influenza A(H3N2) viruses were antigenically characterized as A/Singapore/INFIMH-16-0019/2016-like by HI testing using antiserum raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
    • 27 viruses showed reduced titer with ferret antisera raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
    • A/Singapore/INFIMH-16-0019/2016-like virus is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
    • 53 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 16 viruses belonged to genetic group 3C.2a and 21 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,336 A(H1N1) viruses characterized were antigenically similar to A/Michigan/45/2015, which is the influenza A(H1N1) component of the 2018-19 Northern Hemisphere influenza vaccine.
    • 39 viruses showed reduced titer with ferret antisera raised against cell culture-propagated A/Michigan/45/2015
    Influenza B:
    Influenza B viruses can be divided into two antigenically distinct lineages represented by B/Yamagata/16/88 and B/Victoria/2/87 viruses. The recommended influenza B components for the 2018-19 Northern Hemisphere influenza vaccine are B/Colorado/06/2017 (Victoria lineage) and B/Phuket/3073/2013 (Yamagata lineage).
    • Nine influenza B viruses were characterized as B/Colorado/06/2017, which belong to the Victoria lineage and are included as an influenza B component of the 2018-19 Northern Hemisphere influenza vaccine.
    • Seven viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
    • 19 influenza B viruses were characterized as B/Phuket/3073/2013-like, which belongs to the Yamagata lineage and is included as an influenza B component of the 2018-19 Northern Hemisphere quadrivalent influenza vaccine.
    • ...
    https://www.canada.ca/en/public-heal...h-16-2019.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: March 17, 2019 to March 23, 2019 (week 12)


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      (PDF format, 900 KB, 9 pages)
      Organization: Public Health Agency of Canada
      Date published: 2019-03-29

      Related Topics



      Overall Summary

      • Influenza activity continues to be reported in almost all regions in Canada but is circulating at higher levels in some eastern regions.
      • Though A(H1N1) peaked at end of December, over the past four weeks a second smaller wave, dominated by A(H3N2), is being observed in most regions of the country.
      • Detections of influenza A(H3N2) have been steadily increasing since mid-January and accounted for 72% of subtyped influenza A detections this week; however, influenza A(H1N1)pdm09 remains the predominant subtype to date this season.
      • Detections of influenza A continue to be greater than those of influenza B. There is currently very little influenza B circulation compared to previous seasons.


      On this page

      Influenza/Influenza-like Illness Activity (geographic spread)

      During week 12, the following influenza activity levels were reported (Figure 1):
      • 15 regions reported localized activity: in Alta.(1), Ont.(6), N.S.(3), N.B.(2), P.E.I.(1) and N.L.(2).
      • 33 regions reported sporadic activity: in B.C.(5), Alta.(4), Sask.(3), Man.(4), Ont.(1), Que.(6), N.B.(5), N.L.(2), N.S.(1), Y.T.(1) and Nvt.(1)
      • Three regions: in Man.(1) and Nvt.(2) reported no activity.



      Figure 1 Map of overall influenza/ILI activity by province and territory, Canada, week 2019-12

      Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

      In week 12, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
      • The percentage of tests positive for influenza continued to increase slightly to 21.8%.
      • A total 1,735 laboratory detections of influenza were reported, of which 93% were influenza A.
      • Influenza A(H3N2) accounted for 72% of subtyped influenza A detections.
      • Detections of influenza A(H3N2) have been steadily increasing, from 93 detections in week 4 (mid-January) to 342 this week.
      To date this season, 39,297 laboratory-confirmed influenza detections have been reported:
      • 98% have been influenza A.
      • Among the 13,414 influenza A viruses subtyped, 81% have been A(H1N1)pdm09.
      • Influenza B often circulates later in the season in Canada (Feb-Apr). Fewer influenza B detections have been reported this season compared to recent seasons at this time of year.
      To date this season, detailed information on age and type/subtype has been received for 30,844 laboratory-confirmed influenza cases (Table 1):
      • 84% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
      • 57% of all influenza A(H3N2) detections have been reported in adults 65 years of age and older.
      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 2 Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2018-35 to 2019-12

      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 equivalent Figure 3 Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-12

      Figure 3 - Text equivalent
      0-4 6093 1639 106 4348 115 6208 20%
      5-19 4425 1359 240 2826 176 4601 15%
      20-44 5905 1882 298 3725 117 6022 20%
      45-64 5915 1800 292 3823 70 5985 19%
      65+ 7852 1320 1265 5267 176 8028 26%
      Total 30190 8000 2201 19989 654 30844 100%
      Table 1 - Note 1 UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available.
      Return to Table 1 - Note1 referrer.
      Syndromic / Influenza-like Illness Surveillance

      Healthcare Professionals Sentinel Syndromic Surveillance

      In week 12, 1.6% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4).
      Figure 4 Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2019-12

      Number of Sentinels Reporting in Week 12: 86
      The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2013-14 to 2017-18
      Figure 4 - Text equivalent Participatory Syndromic Surveillance

      In week 12, 2,056 participants reported to FluWatchers, of which 50 (2.4%) reported symptoms of cough and fever (Figure 5).
      Among the 50 participants who reported fever and cough:
      • 30% consulted a healthcare professional;
      • 92% reported days missed from work or school, resulting in a combined total of 136 missed days of work or school.
      Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-12

      Number of Participants Reporting in Week 12: 2,056
      Figure 5 - Text equivalent Influenza Outbreak Surveillance

      In week 12, 38 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (19), acute care facilities (8) and other settings (11). Eleven new ILI outbreaks (LTCF (8) and schools and daycares (3)) were also reported in week 12. Among the outbreaks with available subtype information (12), 92% (11) were associated with influenza A(H3N2).
      To date this season, 633 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
      • 371 (59%) outbreaks were in LTCF, 30 were in schools and daycares, 94 in acute care facilities, and 138 were in other settings.
      • Among the 563 outbreaks for which the influenza type was available, 98% (550) were associated with influenza A.
      • Among the 243 outbreaks for which the influenza A subtype was available, 55% (125) were associated with influenza A(H1N1)pdm09;
      To date this season, 134 ILI outbreaks have been reported; 75 occurred in LTCF, 55 in schools, and four in acute care facilities.
      Figure 6 Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-12

      Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

      Provincial/Territorial Influenza Hospitalizations and Deaths
      To date this season, 2,592 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
      Hospitalizations (Table 2):
      • 98.7% (2,558) were associated with influenza A
      • Among the 1,555 cases for which the influenza subtype was available, 1,366 (88%) were associated with A(H1N1)pdm09.
      • The highest estimated rate of hospitalization is among adults over 65 years of age.
      Intensive Care Unit (ICU) cases and deaths:
      • To date this season 464 ICU admissions and 127 deaths have been reported.
        • 43% (199) of reported ICU admissions were in adults aged 45-64 years.
        • All but four ICU admissions were associated with influenza A.
        • All but one of the deaths were associated with influenza A.
      0-4 354 12 76.89
      5-19 210 10 15.85
      20-44 317 4 11.28
      45-64 688 3 31.75
      65+ 989 5 81.70
      Total 2558 34
      % 98.7% 1.3%
      Table 2 - Note 1 Influenza-associated hospitalizations are reported by Alberta, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Prince Edward Island and Yukon. Only hospitalizations that require intensive medical care are reported by Saskatchewan. The cumulative rate of hospitalizations is calculated using the total population by age-group in participating provinces and territories.
      Return to Table 2 - Note1
      Pediatric Influenza Hospitalizations and Deaths

      In week 12, 41 pediatric (≤16 years of age) hospitalizations with influenza have been reported by the Immunization Monitoring Program Active (IMPACT) network (Figure 7). Of the 41 hospitalizations, 34 (83%) were due to influenza A.
      To date this season, 1,089 pediatric hospitalizations have been reported (Figure 8):
      • 67% of cases were in children under 5 years of age.
      • 97% (1,054) of cases have been associated with influenza A.
      • Among the 324 cases for which the influenza subtype was available, 289 (89%) were associated with A(H1N1)pdm09.
      To date this season, 194 ICU admissions, and 10 deaths have been reported.
      • 60% (117) of ICU admissions were in children under 5 years of age.
      • All but two of the ICU admissions have been associated with influenza A.
      • 80% (8) of deaths occurred in children 2 to 4 years of age.
      • All deaths have been associated with influenza A.
      Figure 7 Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2019-12

      The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
      Figure 7 - Text equivalent Figure 8 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, weeks 2018-35 to 2019-12

      Figure 8 - Text equivalent Adult Influenza Hospitalizations and Deaths

      Surveillance of laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network began on November 1st for the 2018-19 season.
      To date this season, 773 hospitalizations, 90 ICU admissions and 40 deaths have been reported (Figure 9):
      • 718 (93%) hospitalizations were associated with influenza A.
      • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (59%) compared to adults <65 years of age (41%).
      • Among the 167 cases for which the influenza subtype was available, 103 (62%) were associated with A(H1N1)pdm09.
      • 88% of hospitalized cases reported more than one type of comorbid condition.
      • The most commonly reported comorbidity was endocrine disorders, which were reported in 83% of hospitalized cases.
      Figure 9 - Cumulative numbers of adult hospitalizations (>20 years of age) with influenza by age-group reported by CIRN, Canada, 2018-19, weeks 2018-44 to 2019-12

      Figure 9 - Text equivalent Influenza Strain Characterizations

      Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,700 influenza viruses (233 A(H3N2), 1,415 A(H1N1) and 52 B) that were received from Canadian laboratories.
      Genetic Characterization of Influenza A(H3N2):

      124 influenza A(H3N2) viruses did not grow to sufficient hemagglutination titer for antigenic characterization by hemagglutination inhibition (HI) assay. Therefore, NML has performed genetic characterization to determine the genetic group identity of these viruses.
      Sequence analysis of the HA gene of the viruses showed that:
      • 18 viruses belonged to genetic group 3C.2a.
      • 102 viruses belonged to subclade 3C.2a1.
      • Three viruses belonged to 3C.3a.
      • One isolate could not be sequenced.
      A/Singapore/INFIMH-16-0019/2016-like virus belongs to genetic group 3C.2a1 and is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
      Antigenic Characterization:

      Influenza A (H3N2):
      • 82 influenza A(H3N2) viruses were antigenically characterized as A/Singapore/INFIMH-16-0019/2016-like by HI testing using antiserum raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
      • 27 viruses showed reduced titer with ferret antisera raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
      • A/Singapore/INFIMH-16-0019/2016-like virus is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
      • 63 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 17 viruses belonged to genetic group 3C.2a and 29 to 3C.3a. Sequencing is pending for the remaining isolates.
      Influenza A(H1N1):
      • 1,375 A(H1N1) viruses characterized were antigenically similar to A/Michigan/45/2015, which is the influenza A(H1N1) component of the 2018-19 Northern Hemisphere influenza vaccine.
      • 40 viruses showed reduced titer with ferret antisera raised against cell culture-propagated A/Michigan/45/2015
      Influenza B:
      Influenza B viruses can be divided into two antigenically distinct lineages represented by B/Yamagata/16/88 and B/Victoria/2/87 viruses. The recommended influenza B components for the 2018-19 Northern Hemisphere influenza vaccine are B/Colorado/06/2017 (Victoria lineage) and B/Phuket/3073/2013 (Yamagata lineage).
      • 18 influenza B viruses were characterized as B/Colorado/06/2017, which belong to the Victoria lineage and are included as an influenza B component of the 2018-19 Northern Hemisphere influenza vaccine.
      • 12 viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
      • 22 influenza B viruses were characterized as B/Phuket/3073/2013-like, which belongs to the Yamagata lineage and is included as an influenza B component of the 2018-19 Northern Hemisphere quadrivalent influenza vaccine.
      • ...
      https://www.canada.ca/en/public-heal...h-23-2019.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: March 24, 2019 to March 30, 2019 (week 13)


        Download the alternative format
        (PDF format, 862 KB, 9 pages)
        Organization: Public Health Agency of Canada
        Date published: 2019-04-05

        Related Topics



        Overall Summary

        • Influenza activity continues to be reported in almost all regions in Canada.
        • Though A(H1N1) peaked at end of December, over the past five weeks a second smaller wave, dominated by A(H3N2), is being observed in most regions of the country.
        • Detections of influenza A(H3N2) have been steadily increasing since mid-January and accounted for 76% of subtyped influenza A detections this week; however, influenza A(H1N1)pdm09 remains the predominant subtype to date this season.
        • Detections of influenza A continue to be greater than those of influenza B. There is currently very little influenza B circulation compared to previous seasons.
        • The 2018-19 Seasonal Influenza Immunization Coverage Survey showed that coverage was low among adults aged 18-64 years (34%) and highest among seniors aged 65 years and older (70%).


        On this page

        Influenza/Influenza-like Illness Activity (geographic spread)

        During week 13, the following influenza activity levels were reported (Figure 1):
        • 21 regions reported localized activity: in Alta.(2), Ont.(6), Que.(2), N.S.(3), N.B.(3), P.E.I.(1), Y.T.(1) and N.L.(3).
        • 26 regions reported sporadic activity: in B.C.(5), Alta.(3), Sask.(3), Man.(3), Ont.(1), Que.(4), N.B.(4), N.L.(1) and N.W.T.(2)
        • Six regions: in Man.(2), N.S.(1) and Nvt.(3) reported no activity.



        Figure 1 Map of overall influenza/ILI activity by province and territory, Canada, week 2019-13

        Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

        In week 13, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
        • The percentage of tests positive for influenza remained steady at 22%.
        • A total 1,579 laboratory detections of influenza were reported, of which 91% were influenza A.
        • Influenza A(H3N2) accounted for 76% of subtyped influenza A detections.
        • Detections of influenza A(H3N2) have been steadily increasing, from 93 detections in week 4 (mid-January) to 358 this week.
        To date this season, 41,372 laboratory-confirmed influenza detections have been reported:
        • 98% have been influenza A.
        • Among the 13,859 influenza A viruses subtyped, 79% have been A(H1N1)pdm09.
        • Influenza B often circulates later in the season in Canada (Feb-Apr). Fewer influenza B detections have been reported this season compared to recent seasons at this time of year.
        To date this season, detailed information on age and type/subtype has been received for 31,770 laboratory-confirmed influenza cases (Table 1):
        • 83% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
        • 58% of all influenza A(H3N2) detections have been reported in adults 65 years of age and older.
        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 2 Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, weeks 2018-35 to 2019-13

        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 equivalent Figure 3 Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-13

        Figure 3 - Text equivalent
        0-4 6148 1644 127 4377 130 6278 20%
        5-19 4537 1366 281 2890 202 4739 15%
        20-44 6059 1910 332 3817 137 6196 20%
        45-64 6079 1832 345 3902 76 6155 19%
        65+ 8224 1360 1479 5385 178 8402 26%
        Total 31047 8112 2564 20371 723 31770 100%
        Table 1 - Note 1 UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available.
        Return to Table 1 - Note1 referrer.
        Syndromic / Influenza-like Illness Surveillance

        Healthcare Professionals Sentinel Syndromic Surveillance

        In week 13, 1.6% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4).
        Figure 4 Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2019-13

        Number of Sentinels Reporting in Week 13: 79
        The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2013-2014 to 2017-2018
        Figure 4 - Text equivalent Participatory Syndromic Surveillance

        In week 13, 2,041 participants reported to FluWatchers, of which 49 (2.4%) reported symptoms of cough and fever (Figure 5).
        Among the 49 participants who reported fever and cough:
        • 16% consulted a healthcare professional;
        • 67% reported days missed from work or school, resulting in a combined total of 110 missed days of work or school.
        Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-13

        Number of Participants Reporting in Week 13: 2,041
        Figure 5 - Text equivalent Influenza Outbreak Surveillance

        In week 13, 31 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (13), acute care facilities (7) and other settings (11). Three new ILI outbreaks (LTCF (2) and schools and daycares (1)) were also reported in week 13. Among the outbreaks with available subtype information (8), all (8) were associated with influenza A(H3N2).
        To date this season, 664 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
        • 385 (58%) outbreaks were in LTCF, 30 were in schools and daycares, 102 in acute care facilities, and 147 were in other settings.
        • Among the 603 outbreaks for which the influenza type was available, 98% (590) were associated with influenza A.
        • Among the 262 outbreaks for which the influenza A subtype was available, 51% (128) were associated with influenza A(H3N2);
        To date this season, 137 ILI outbreaks have been reported; 77 occurred in LTCF, 56 in schools, and four in acute care facilities.
        Figure 6 Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-13

        Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

        Provincial/Territorial Influenza Hospitalizations and Deaths
        To date this season, 2,701 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
        Hospitalizations (Table 2):
        • 98.4% (2,659) were associated with influenza A
        • Among the 1,629 cases for which the influenza subtype was available, 1,380 (85%) were associated with A(H1N1)pdm09.
        • The highest estimated rate of hospitalization is among adults over 65 years of age.
        Intensive Care Unit (ICU) cases and deaths:
        • To date this season 474 ICU admissions and 139 deaths have been reported.
          • 43% (202) of reported ICU admissions were in adults aged 45-64 years.
          • All but four ICU admissions were associated with influenza A.
          • All but one of the deaths were associated with influenza A.
        0-4 361 15 79.00
        5-19 218 13 16.65
        20-44 327 4 11.63
        45-64 704 4 32.53
        65+ 1049 6 86.71
        Total 2659 42
        % 98.4% 1.6%
        Table 2 - Note 1 Influenza-associated hospitalizations are reported by Alberta, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Prince Edward Island and Yukon. Only hospitalizations that require intensive medical care are reported by Saskatchewan. The cumulative rate of hospitalizations is calculated using the total population by age-group in participating provinces and territories.
        Return to Table 2 - Note1
        Pediatric Influenza Hospitalizations and Deaths

        In week 13, 30 pediatric (≤16 years of age) hospitalizations with influenza have been reported by the Immunization Monitoring Program Active (IMPACT) network (Figure 7). Of the 30 hospitalizations, 27 (90%) were due to influenza A.
        To date this season, 1,116 pediatric hospitalizations have been reported (Figure 8):
        • 67% of cases were in children under 5 years of age.
        • 96% (1,076) of cases have been associated with influenza A.
        • Among the 330 cases for which the influenza subtype was available, 289 (89%) were associated with A(H1N1)pdm09.
        To date this season, 197 ICU admissions, and 10 deaths have been reported.
        • 60% (119) of ICU admissions were in children under 5 years of age.
        • All but six of the ICU admissions have been associated with influenza A.
        • 80% (8) of deaths occurred in children 2 to 4 years of age.
        • All deaths have been associated with influenza A.
        Figure 7 Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2019-13

        The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
        Figure 7 - Text equivalent Figure 8 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, weeks 2018-35 to 2019-13

        Figure 8 - Text equivalent Adult Influenza Hospitalizations and Deaths

        Surveillance of laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network began on November 1st for the 2018-19 season.
        To date this season, 812 hospitalizations, 98 ICU admissions and 43 deaths have been reported (Figure 9):
        • 757 (93%) hospitalizations were associated with influenza A.
        • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (59%) compared to adults <65 years of age (41%).
        • Among the 169 cases for which the influenza subtype was available, 105 (62%) were associated with A(H1N1)pdm09.
        • 88% of hospitalized cases reported more than one type of comorbid condition.
        • The most commonly reported comorbidity was endocrine disorders, which were reported in 83% of hospitalized cases.
        Figure 9 - Cumulative numbers of adult hospitalizations (>20 years of age) with influenza by age-group reported by CIRN, Canada, 2018-19, weeks 2018-44 to 2019-13

        Figure 9 - Text equivalent Influenza Strain Characterizations

        Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,745 influenza viruses (244 A(H3N2), 1,445 A(H1N1) and 56 B) that were received from Canadian laboratories.
        Genetic Characterization of Influenza A(H3N2):

        130 influenza A(H3N2) viruses did not grow to sufficient hemagglutination titer for antigenic characterization by hemagglutination inhibition (HI) assay. Therefore, NML has performed genetic characterization to determine the genetic group identity of these viruses.
        Sequence analysis of the HA gene of the viruses showed that:
        • 18 viruses belonged to genetic group 3C.2a.
        • 108 viruses belonged to subclade 3C.2a1.
        • Three viruses belonged to 3C.3a.
        • One isolate could not be sequenced.
        A/Singapore/INFIMH-16-0019/2016-like virus belongs to genetic group 3C.2a1 and is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
        Antigenic Characterization:

        Influenza A (H3N2):
        • 85 influenza A(H3N2) viruses were antigenically characterized as A/Singapore/INFIMH-16-0019/2016-like by HI testing using antiserum raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
        • 29 viruses showed reduced titer with ferret antisera raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
        • A/Singapore/INFIMH-16-0019/2016-like virus is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
        • 64 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 17 viruses belonged to genetic group 3C.2a and 29 to 3C.3a. Sequencing is pending for the remaining isolates.
        Influenza A(H1N1):
        • 1,404 A(H1N1) viruses characterized were antigenically similar to A/Michigan/45/2015, which is the influenza A(H1N1) component of the 2018-19 Northern Hemisphere influenza vaccine.
        • 41 viruses showed reduced titer with ferret antisera raised against cell culture-propagated A/Michigan/45/2015
        Influenza B:
        Influenza B viruses can be divided into two antigenically distinct lineages represented by B/Yamagata/16/88 and B/Victoria/2/87 viruses. The recommended influenza B components for the 2018-19 Northern Hemisphere influenza vaccine are B/Colorado/06/2017 (Victoria lineage) and B/Phuket/3073/2013 (Yamagata lineage).
        • 15 influenza B viruses were characterized as B/Colorado/06/2017, which belong to the Victoria lineage and are included as an influenza B component of the 2018-19 Northern Hemisphere influenza vaccine.
        • 19 viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
        • 22 influenza B viruses were characterized as B/Phuket/3073/2013-like, which belongs to the Yamagata lineage and is included as an influenza B component of the 2018-19 Northern Hemisphere quadrivalent influenza vaccine.
        • ...
        https://www.canada.ca/en/public-heal...h-30-2019.html


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