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    started a topic Canada FluWatch Weekly Reports 2018-2019 Season Week 20

    Canada FluWatch Weekly Reports 2018-2019 Season Week 20

    FluWatch report: November 18, 2018 to November 24, 2018 (Week 47)


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    (PDF format, 909 KB, 9 pages)
    Organization: Public Health Agency of Canada
    Date published: 2018-11-30

    Related Topics





    Overall Summary

    • Influenza activity continued to increase in week 47.
    • Influenza A is the most common influenza virus circulating in Canada, and the majority of these viruses are A(H1N1)pdm09.
    • The number of influenza-associated hospitalizations continued to increase in week 47. In particular, the number of pediatric hospitalizations is significantly higher than in recent years.


    On this page

    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 47, influenza activity levels increased slightly compared to the previous week (Figure 1):
    • One region reported widespread activity: in Que.(1),
    • Four regions reported localized activity: in Alta.(1), Ont.(2), and N.B.(1),
    • Sporadic activity was reported by 32 regions, in B.C.(5), Alta.(4), Sask.(3), Man.(3), Ont.(3), Que.(5), N.B.(2), N.S.(1), P.E.I.(1), N.L.(2), N.W.T(2) and Nvt.(1).
    • No activity was reported by 16 regions.



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2018-47

    Figure 1 - Text description Laboratory Confirmed Influenza Detections

    In week 47, the following results were reported from sentinel laboratories across Canada (Figure 2):
    • The percentage of tests positive for influenza continued to increase to 15.3% of tests positive.
    • The percentage of tests positive for influenza A is higher for this time of year compared to the same period during the previous eight seasons.
    • In week 47, 950 laboratory detections of influenza were reported, of which 99% were influenza A.
    To date this season 3,176 laboratory-confirmed influenza detections have been reported (Figure 3):
    • 92% have been influenza A.
    • Among the 1,760 influenza A viruses subtyped, 82% have been A(H1N1)pdm09.
    • Provincial and territorial differences in influenza type/subtype distribution are observed (Figure 3).
    To date this season, detailed information on age and type/subtype has been received for 3,155 laboratory-confirmed influenza cases (Table 1):
    • 69% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 45 years of age.
    • 70% 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 2018-47

    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 Figure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2018-47

    Figure 3 - Text description
    0-4 632 377 3 252 5 637 20%
    5-19 650 334 5 311 11 661 21%
    20-44 797 399 15 383 9 806 26%
    45-64 565 285 32 248 7 572 18
    65+ 465 206 131 128 14 479 15%
    Total 3109 1601 186 1322 46 3155 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 47, 1.9% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4). The percentage of visits for ILI is within expected levels.
    Figure 4 – Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2018-47

    Number of Sentinels Reporting in Week 47: 84
    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 description Participatory Syndromic Surveillance

    In week 47, 2,182 participants reported to FluWatchers, of which 29 (1.3%) reported symptoms of cough and fever (Figure 5).
    Among the 29 participants who reported fever and cough:
    • 28% consulted a healthcare professional;
    • 83% reported days missed from work or school, resulting in a combined total of 66 missed days of work or school.
    Figure 5 – Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2018-47

    Number of Participants Reporting in Week 47: 2,182
    Figure 5 - Text description Influenza Outbreak Surveillance

    In week 47, five new laboratory-confirmed influenza outbreaks were reported in long-term care (3) and acute care (2) facilities.
    To date this season, 36 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 19 outbreaks were in LTCF, eight were in schools, and five were in other settings.
    • All of the 30 outbreaks for which the influenza type was available were associated with influenza A.
    • Among the 21 outbreaks for which the influenza A subtype was available:
      • 17 were associated with influenza A(H1N1)pdm09;
      • Four were associated with A(H3N2);
    One new ILI outbreak in a LTCF was reported in week 47.
    To date this season, 25 ILI outbreaks have been reported; 23 occurred in LTCF, one in a school, and one in an acute care facility.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2018-47

    Figure 6 - Text description Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths

    To date this season, more than 471 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99% (471) were associated with influenza A
    • The highest estimated rates of hospitalization are among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 49 ICU admissions and nine deaths have been reported.
    Footnote 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 footnote1referrer
    0-4 95 0 7.77
    5-19 64 0 2.31
    20-44 72 0 1.20
    45-64 115 0 2.39
    65+ 125 <5 5.18
    Total 471 <5
    % 99% 1%
    Table 2 - Footnote 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 - Footnote1referrer
    Pediatric Influenza Hospitalizations and Deaths

    In week 47, 34 pediatric (≤16 years of age) hospitalizations with influenza have been reported by the Immunization Monitoring Program Active (IMPACT) network. Pediatric hospitalizations reported by IMPACT are at levels not normally seen until late December (4-6 weeks earlier than in recent seasons) (Figure 7).
    To date this season, 145 pediatric hospitalizations have been reported (Figure 8):
    • All but two cases have been associated with influenza A.
    • Among the 109 cases for which the influenza subtype was available, 108 were associated with A(H1N1)pdm09.
    To date this season, 18 ICU admissions, and no deaths have been reported.
    Figure 7 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2018-47

    Figure 7 - Text description 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 2018-47

    Figure 8 - Text description 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, 17 hospitalizations have been reported, of which 15 were associated with influenza A and 2 with influenza B.
    Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 101 influenza viruses (11 A(H3N2), 80 A(H1N1) and 10 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A (H3N2):

    Ten 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:
    • One virus belonged to genetic group 3C.2a.
    • Nine viruses belonged to subclade 3C.2a1.
    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):

    • One influenza A(H3N2) virus was 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.
    • A/Singapore/INFIMH-16-0019/2016-like virus is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.
    • The influenza A (H3N2) virus characterized belonged to genetic group 3C.2a1.
    Influenza A(H1N1):

    • 80 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.
    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).
    • Ten 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...r-24-2018.html



  • Pathfinder
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    FluWatch report: May 12 to May 18, 2019 (Week 20)


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    Organization: Public Health Agency of Canada
    Date published: 2019-05-24

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    Overall Summary

    • Influenza activity in Canada continues to decline. All indicators of influenza activity are decreasing and within the expected range for this time of year.
    • Influenza A(H3N2) and influenza B continue to co-circulate; however, the level of influenza B circulation continues to be very low compared to previous seasons.
    • This week, detections of influenza A continue to be greater than those of influenza B, and 85% of subtyped influenza A detections were A(H3N2).
    • Influenza A(H1N1)pdm09 remains the predominant subtype overall for the 2018-19 season (70% of subtyped influenza A detections).
    • This is the last weekly FluWatch report for the 2018-19 season. Monthly reports will be published over the summer on the last Friday of each month: June 28, July 26, and August 30. Weekly reporting of laboratory detections of respiratory viruses will continue via our Respiratory Virus Detections Surveillance System.

    On this page




    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 20, the following influenza activity levels were reported (Figure 1):
    • 6 regions reported localized activity: in Man.(1), and Ont.(5).
    • 25 regions reported sporadic activity: in B.C.(5), Sask.(3), Man.(3), Ont. (2), Que.(6), N.S.(1), N.B.(4), and P.E.I.(1).
    • 13 regions in 6 different provinces and territories reported no activity.
    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-20

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 20, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
    • The percentage of tests positive for influenza decreased from 12% to 10% in week 20.
    • A total of 469 laboratory detections of influenza were reported, of which 72% were influenza A.
    • Influenza A(H3N2) accounted for 85% of subtyped influenza A detections.
    To date this season, 47,622 laboratory-confirmed influenza detections have been reported:
    • 96% have been influenza A.
    • Among the 16,126 influenza A viruses subtyped, 70% have been A(H1N1)pdm09.
    • Fewer influenza B detections have been reported this season compared to recent seasons at this time of year. The percentage of tests positive for influenza B in week 20 was similar to the previous week.
    To date this season, detailed information on age and type/subtype has been received for 38,249 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 2019-20

    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.
    Data for week 14 excludes subtyping results from one jurisdiction due to batch reporting of subtype information. The results for week 14 should be interpreted with caution.
    Figure 2 - Text equivalent Figure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-20

    Figure 3 - Text equivalent
    0-4 6739 1691 257 4791 306 7045 18%
    5-19 5154 1392 484 3278 524 5678 15%
    20-44 6885 2019 613 4253 337 7222 19%
    45-64 7025 1973 668 4384 123 7148 19%
    65+ 10902 1485 2749 6668 254 11156 29%
    Total 36705 8560 4771 23374 1544 38249 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 20, 0.8% 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 2019-20

    Number of Sentinels Reporting in Week 20: 74
    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

    FluWatchers surveillance has ended for the 2018-19 influenza season. On average 2,097 participants reported to FluWatchers each week, resulting in 64,672 questionnaires completed this season. The proportion of participants reporting fever and cough peaked in week 51 at 3.9% (Figure 5). Approximately 63% of FluWatchers participants reported being vaccinated for influenza in the 2018-19 season.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-18

    Number of Participants Reporting in Week 18: 1,951
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 20, three new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (1) acute care facilities (1) and other settings (1). One new ILI outbreak was reported in a LTCF. All the influenza outbreaks were associated with influenza A.
    To date this season, 848 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 504 (59%) outbreaks were in LTCF, 30 were in schools and daycares, 121 in acute care facilities, and 193 were in other settings.
    • Among the 761 outbreaks for which the influenza type was available, 98% (743) were associated with influenza A.
    • Among the 327 outbreaks for which the influenza A subtype was available, 60% (196) were associated with influenza A(H3N2);
    To date this season, 160 ILI outbreaks have been reported; 94 occurred in LTCF, 61 in schools, one in other settings and four in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-20

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 3,097 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1. Note that data from one participating jurisdiction has not been available since surveillance week 13, so these figures are an underestimate of cases for this season.
    Hospitalizations (Table 2):
    • 97.6% (3,023) were associated with influenza A
    • Among the 1,710 cases for which the influenza subtype was available, 1,415 (83%) 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 557 ICU admissions and 184 deaths have been reported.
      • 41% (227) of reported ICU admissions were in adults aged 45-64 years.
      • All but nine ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 395 23 87.82
    5-19 235 20 18.38
    20-44 355 10 12.83
    45-64 777 7 36.03
    65+ 1261 14 104.79
    Total 3023 74
    % 97.6% 2.4%
    Table 2 – Note 1 Influenza-associated hospitalizations are reported by N.L., P.E.I, N.S., N.B., Man., Alb., Y.T. and N.W.T. Only hospitalizations that require intensive medical care are reported by Sask. The cumulative rate of hospitalizations is calculated using the population by age-group in participating provinces and territories.
    Return to Table 2 – Note1
    Pediatric Influenza Hospitalizations and Deaths

    To date this season, 1,298 pediatric hospitalizations have been reported (Figure 7 & 8):
    • 66% of cases were in children under 5 years of age.
    • 93% (1,201) of cases have been associated with influenza A.
    • Among the 376 cases for which the influenza subtype was available, 305 (81%) were associated with A(H1N1)pdm09.
    To date this season, 246 ICU admissions, and 10 deaths have been reported.
    • 59% (148) of ICU admissions were in children under 5 years of age.
    • All but 16 (94%) of the ICU admissions have been associated with influenza A; 83% of the 106 cases for which the influenza A subtype was available were associated with A(H1N1)pdm09.
    • 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 2019-20

    The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-19
    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 2019-20

    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, 944 hospitalizations, 117 ICU admissions and 54 deaths have been reported (Figure 9):
    • 873 (92%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (60%) compared to adults <65 years of age (40%).
    • Among the 207 cases for which the influenza subtype was available, 107 (52%) were associated with A(H1N1)pdm09.
    • 87% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 87% 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 2019-20

    Figure 9 - Text equivalent Influenza Strain Characterizations

    From September 1, 2018 to 23 May, 2019, the National Microbiology Laboratory (NML) has characterized 2,252 influenza viruses (488 A(H3N2), 1,612 A(H1N1) and 152 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    191 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:
    • 20 viruses belonged to genetic group 3C.2a.
    • 168 viruses belonged to subclade 3C.2a1.
    • Four 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):
    • 162 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.
    • 133 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.
    • 101 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 20 viruses belonged to genetic group 3C.2a and 116 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,569 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.
    • 43 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).
    • 29 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.
    • 100 viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017. Sequence analysis showed that 99 viruses that showed reduced titer had a three amino acid deletion (162-164) in the HA gene.
    • 23 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.
    Antiviral Resistance

    Antiviral Resistance – Amantadine:

    449 influenza A (89 A(H3N2) and 360 A(H1N1)) viruses were tested for resistance to amantadine and it was found that:
    • All 449 influenza A viruses were resistant to amantadine.
    Antiviral Resistance – Oseltamivir:

    1,287 influenza viruses (167 A(H3N2), 1,039 A(H1N1) and 81 B) were tested for resistance to oseltamivir and it was found that:
    • All 167 A(H3N2) viruses were sensitive to oseltamivir.
    • Of the 1,039 A(H1N1) viruses tested, 1,035 were sensitive to oseltamivir and four viruses were resistant to oseltamivir with a H275Y mutation.
    • All 81 B viruses were sensitive to oseltamivir.
    Antiviral Resistance – Zanamivir:

    1,286 influenza viruses (167 A(H3N2), 1,038 H1N1 and 81 B) were tested for resistance to zanamivir and it was found that:
    • All 1,286 influenza viruses were sensitive to zanamivir.
    Vaccine Monitoring

    Vaccine monitoring refers to activities related to the monitoring of influenza vaccine coverage and effectiveness.
    Vaccine Coverage

    The Seasonal Influenza Immunization Coverage Survey is an annual telephone survey conducted between January and February that collects information related to the influenza vaccine in Canada. This survey measures vaccine coverage, which is the percentage of people who received the annual seasonal influenza vaccine in a specific influenza season.
    In the 2018-19 influenza season, coverage was:
    • 34% among adults aged 18 to 64 years.
      • 31% among adults aged 18-64 wihout chronic diseases.
      • 43% among adults aged 18 to 64 years with chronic diseases.
    • 70% among seniors (aged 65 years and older).
    All adults (≥18) 1568 36.6 2150 46.8 3726 41.8
    18-64 1252 28.6 1640 39.9 2898 34.3
    without chronic diseases 948 25.8 1171 36.1 2124 30.8
    with chronic diseases 304 36.3 465 48.5 770 42.8
    ≥65 316 69.0 510 70.9 828 69.9
    Table 3 – Note 1 Excluded from stratified analysis: eight people who did not disclose their gender and four people (18-64 years old) who did disclose whether they had any chronic diseases.
    Return to Table 3 – Note1 referrer.
    Vaccine Effectiveness

    Vaccine effectiveness (VE) is a measure of how well the influenza vaccine is able to prevent influenza illness. Throughout the influenza season, surveillance networks estimate how well the influenza vaccine is working. Estimates can vary depending on several factors such as the study methods; the population, setting and outcomes that are being studied; the type and mix of vaccine products; the stage of the season and the kinds of influenza viruses that are circulating when the study is conducted.
    The community-based Canadian Sentinel Practitioner Surveillance Network (SPSN) published an interim VE estimate in January 2019 for A(H1N1)pdm09. Subsequently, given an atypical late-season wave of influenza A(H3N2),SPSN has undertaken an additional interim analysis to assess effectiveness of the 2018/19 influenza vaccine against medically-attended outpatient A(H3N2) illness. Vaccine effectiveness (VE) monitoring methods and results are available at the SPSN website.
    Based on data collected as of March 30th, 2019 from more than 2800 patients from B.C., Alta., Ont., and Que., the 2018/19 northern hemisphere vaccine effectiveness has varied depending on the strain.
    • A(H1N1)pdm09: In the first interim analysis, VE against A(H1N1)pdm09 was 72% (95% CI: 60 to 81) overall, with substantial protection observed in all age groups. In the most recent analysis as of March 30th, estimates against A(H1N1)pmd09 have remained stable at approximately 70%.
    • A(H3N2): In the most recent analysis, VE against A(H3N2) was 23% (95% CI: -9 to 46) overall. As the confidence interval crosses zero, this estimate does not provide evidence of vaccine protection against medically-attended outpatient A(H3N2) illness.
    The SPSN continues to monitor and will further update VE estimates at end of season.

    https://www.canada.ca/en/public-heal...y-18-2019.html


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  • Pathfinder
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    FluWatch report: May 5 to May 11, 2019 (Week 19)


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    (PDF format, 1.17 MB, 10 pages)
    Organization: Public Health Agency of Canada
    Date published: 2019-05-17

    Related Topics

    Overall Summary
    • Influenza activity continues to decline overall.
    • Influenza A(H3N2) was the predominant subtype this week (83% of subtyped influenza A detections); however, influenza A(H1N1)pdm09 remains the predominant subtype to date this season (71% of subtyped influenza A detections).
    • 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 19, the following influenza activity levels were reported (Figure 1):
    • 7 regions reported localized activity: in Ont.(4), Que.(3).
    • 29 regions reported sporadic activity: in B.C.(4), Sask.(2), Man.(5), Ont. (3), Que.(3), N.S.(2), N.B.(6), N.L.(1), Nvt. (2) and N.W.T.(1)
    • 12 regions in 9 different provinces and territories reported no activity.
    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-19

    Figure 1 - Text equivalentLaboratory-Confirmed Influenza Detections

    In week 19, the following results were reported from sentinel laboratories across (Figures 2 and 3):
    • The percentage of tests positive for influenza increased slightly from 11% to 12% in week 19.
    • A total of 592 laboratory detections of influenza were reported, of which 76% were influenza A.
    • Influenza A(H3N2) accounted for 83% of subtyped influenza A detections.
    To date this season, 47,143 laboratory-confirmed influenza detections have been reported:
    • 96% have been influenza A.
    • Among the 15,938 influenza A viruses subtyped, 71% 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. The percentage of tests positive for influenza B in week 19 was similar to the previous week.
    To date this season, detailed information on age and type/subtype has been received for 37,844 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 2019-19

    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.
    Data for week 14 excludes subtyping results from one jurisdiction due to batch reporting of subtype information. The results for week 14 should be interpreted with caution.
    Figure 2 - Text equivalentFigure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-19

    Figure 3 - Text equivalent
    0-4 6707 1689 248 4770 286 6993 18%
    5-19 5127 1389 471 3267 482 5609 15%
    20-44 6847 2012 596 4239 308 7155 19%
    45-64 6964 1963 632 4369 115 7079 19%
    65+ 10761 1480 2667 6614 247 11008 29%
    Total 36406 8533 4614 23259 1438 37844 100%
    Table 1 – Note 1UnS: 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 19, 0.8% 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 2019-19

    Number of Sentinels Reporting in Week 19: 72
    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 equivalentParticipatory Syndromic Surveillance

    FluWatchers surveillance has ended for the 2018-19 influenza season. On average 2,097 participants reported to FluWatchers each week, resulting in 64,672 questionnaires completed this season. The proportion of participants reporting fever and cough peaked in week 51 at 3.9% (Figure 5). Approximately 63% of FluWatchers participants reported being vaccinated for influenza in the 2018-19 season.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-18

    Number of Participants Reporting in Week 18: 1,951

    Figure 5 - Text equivalentInfluenza Outbreak Surveillance

    In week 19, 11 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (8) acute care facilities (1) and other settings (2). Four new ILI outbreaks were reported in LTCF. Among the outbreaks with available information (11), 10 were associated with influenza A (of which 2 were associated with A(H3N2)), and one outbreak was associated with influenza B.
    To date this season, 838 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 496 (59%) outbreaks were in LTCF, 30 were in schools and daycares, 120 in acute care facilities, and 192 were in other settings.
    • Among the 752 outbreaks for which the influenza type was available, 98% (734) were associated with influenza A.
    • Among the 323 outbreaks for which the influenza A subtype was available, 59% (192) were associated with influenza A(H3N2);
    To date this season, 157 ILI outbreaks have been reported; 91 occurred in LTCF, 61 in schools, one in other settings and four in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-19

    Figure 6 - Text equivalentSevere Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 3,092 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1. Note that data from one participating jurisdiction has not been available since surveillance week 13, so these figures are an underestimate of cases for this season.
    Hospitalizations (Table 2):
    • 97.6% (3,018) were associated with influenza A
    • Among the 1,704 cases for which the influenza subtype was available, 1,414 (83%) 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 555 ICU admissions and 182 deaths have been reported.
      • 41% (227) of reported ICU admissions were in adults aged 45-64 years.
      • All but eight ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 394 23 87.61
    5-19 235 20 18.38
    20-44 354 10 12.79
    45-64 776 7 35.98
    65+ 1259 14 104.63
    Total 3018 74
    % 97.6% 2.4%
    Table 2 – Note 1Influenza-associated hospitalizations are reported by N.L., P.E.I, N.S., N.B., Man., Alb., Y.T. and N.W.T. Only hospitalizations that require intensive medical care are reported by Sask. The cumulative rate of hospitalizations is calculated using the population by age-group in participating provinces and territories.
    Return to Table 2 – Note1
    Pediatric Influenza Hospitalizations and Deaths

    To date this season, 1,280 pediatric hospitalizations have been reported (Figure 7 & 8):
    • 66% of cases were in children under 5 years of age.
    • 93% (1,192) of cases have been associated with influenza A.
    • Among the 375 cases for which the influenza subtype was available, 305 (81%) were associated with A(H1N1)pdm09.
    To date this season, 246 ICU admissions, and 10 deaths have been reported.
    • 58% (142) of ICU admissions were in children under 5 years of age.
    • All but 13 (95%) of the ICU admissions have been associated with influenza A; 84% of the 105 cases for which the influenza A subtype was available were associated with A(H1N1)pdm09.
    • 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 2019-19

    The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
    Figure 7 - Text equivalentFigure 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 2019-19

    Figure 8 - Text equivalentAdult 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, 942 hospitalizations, 115 ICU admissions and 54 deaths have been reported (Figure 9):
    • 873 (93%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (60%) compared to adults <65 years of age (40%).
    • Among the 204 cases for which the influenza subtype was available, 107 (52%) were associated with A(H1N1)pdm09.
    • 86% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 87% 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 2019-19

    Figure 9 - Text equivalentInfluenza Strain Characterizations

    From September 1, 2018 to 16 May, 2019, the National Microbiology Laboratory (NML) has characterized 2 170 influenza viruses (440 A(H3N2), 1,594 A(H1N1) and 136 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    191 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:
    • 20 viruses belonged to genetic group 3C.2a.
    • 168 viruses belonged to subclade 3C.2a1.
    • Four 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):
    • 148 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.
    • 99 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.
    • 101 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 20 viruses belonged to genetic group 3C.2a and 116 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,551 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.
    • 43 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).
    • 25 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.
    • 88 viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017. Sequence analysis showed that 87 viruses that showed reduced titer had a three amino acid deletion (162-164) in the HA gene.
    • 23 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.
    • ...
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  • Pathfinder
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    FluWatch report: April 28 to May 4, 2019 (Week 18)

    Overall Summary
    Overall Summary
    Overall Summary
    Overall Summary
    • Influenza activity continues to decline overall despite ongoing circulation of influenza A(H3N2) and influenza B in many regions across the country.
    • Influenza A(H3N2) was the predominant subtype this week (84% of subtyped influenza A detections); however, influenza A(H1N1)pdm09 remains the predominant subtype to date this season (71% of subtyped influenza A detections).
    • 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 18, the following influenza activity levels were reported (Figure 1):
    • 14 regions reported localized activity: in Ont.(6), Que.(3), N.B.(1), N.S.(1), and N.L.(3).
    • 26 regions reported sporadic activity: in B.C.(5), Sask.(3), Man.(5), Que.(4), N.S.(1), N.B.(6), P.E.I (1), and N.W.T.(1)
    • Five regions in four different provinces reported no activity.


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    Organization: Public Health Agency of Canada
    Date published: 2019-05-10

    Related Topics





    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-18

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 18, the following results were reported from sentinel laboratories across (Figures 2 and 3):
    • The percentage of tests positive for influenza decreased from 14% to 11% in week 18.
    • A total of 609 laboratory detections of influenza were reported, of which 76% were influenza A.
    • Influenza A(H3N2) accounted for 84% of subtyped influenza A detections.
    To date this season, 46,549 laboratory-confirmed influenza detections have been reported:
    • 96% have been influenza A.
    • Among the 15,749 influenza A viruses subtyped, 71% 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. The percentage of tests positive for influenza B in week 18 was similar to the previous week.
    To date this season, detailed information on age and type/subtype has been received for 37,331 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 2019-18

    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.
    Data for week 14 excludes subtyping results from one jurisdiction due to batch reporting of subtype information. The results for week 14 should be interpreted with caution.
    Figure 2 - Text equivalent Figure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-18

    Figure 3 - Text equivalent
    0-4 6673 1688 238 4747 261 6934 19%
    5-19 5082 1388 458 3236 422 5504 15%
    20-44 6796 2005 577 4214 291 7087 19%
    45-64 6899 1954 614 4331 108 7007 19%
    65+ 10560 1474 2579 6507 239 10799 29%
    Total 36010 8509 4466 23035 1321 37331 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 18, 0.7% 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 2019-18

    Number of Sentinels Reporting in Week 18: 63
    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 18, 1,951 participants reported to FluWatchers, of which 38 (1.9%) reported symptoms of cough and fever (Figure 5).
    Among the 38 participants who reported fever and cough:
    • 26% consulted a healthcare professional;
    • 79% reported days missed from work or school, resulting in a combined total of 81 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-18

    Number of Participants Reporting in Week 18: 1,951
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 18, 11 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (7) acute care facilities (1) and other settings (3). No new ILI outbreaks were reported. Among the outbreaks with available information (9), 8 were associated with influenza A (of which 3 were associated with A(H3N2)), and one outbreak was associated with influenza B.
    To date this season, 819 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 484 (59%) outbreaks were in LTCF, 30 were in schools and daycares, 118 in acute care facilities, and 187 were in other settings.
    • Among the 733 outbreaks for which the influenza type was available, 98% (716) were associated with influenza A.
    • Among the 315 outbreaks for which the influenza A subtype was available, 58% (184) were associated with influenza A(H3N2);
    To date this season, 151 ILI outbreaks have been reported; 85 occurred in LTCF, 61 in schools, one in other settings and four in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-18

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 3,075 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 97.7% (3,005) were associated with influenza A
    • Among the 1,696 cases for which the influenza subtype was available, 1,414 (83%) 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 555 ICU admissions and 179 deaths have been reported.
      • 41% (227) of reported ICU admissions were in adults aged 45-64 years.
      • All but eight ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 394 21 87.19
    5-19 235 20 18.38
    20-44 351 9 12.65
    45-64 775 6 35.89
    65+ 1250 14 103.89
    Total 3005 70
    % 97.7% 2.3%
    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

    To date this season, 1,265 pediatric hospitalizations have been reported (Figure 7 & 8):
    • 66% of cases were in children under 5 years of age.
    • 94% (1,187) of cases have been associated with influenza A.
    • Among the 373 cases for which the influenza subtype was available, 305 (82%) were associated with A(H1N1)pdm09.
    To date this season, 243 ICU admissions, and 10 deaths have been reported.
    • 58% (142) of ICU admissions were in children under 5 years of age.
    • All but 12 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 2019-18

    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 2019-18

    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, 936 hospitalizations, 111 ICU admissions and 51 deaths have been reported (Figure 9):
    • 869 (93%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (60%) compared to adults <65 years of age (40%).
    • Among the 202 cases for which the influenza subtype was available, 106 (52%) were associated with A(H1N1)pdm09.
    • 89% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 86% 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 2019-18

    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 2,124 influenza viruses (418 A(H3N2), 1,575 A(H1N1) and 131 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    191 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:
    • 20 viruses belonged to genetic group 3C.2a.
    • 166 viruses belonged to subclade 3C.2a1.
    • Four 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):
    • 141 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.
    • 86 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.
    • 97 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 19 viruses belonged to genetic group 3C.2a and 107 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,532 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.
    • 43 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).
    • 24 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.
    • 84 viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017. Sequence analysis showed that 83 viruses that showed reduced titer had a three amino acid deletion (162-164) in the HA gene.
    • 23 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...ay-4-2019.html


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  • Pathfinder
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    FluWatch report: April 14 to April 20, 2019 (Week 16)


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    Organization: Public Health Agency of Canada
    Date published: 2019-04-26

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    Overall Summary

    • Influenza continues to circulate in many regions across the country.
    • The second smaller wave of influenza activity, dominated by A(H3N2), decreased this week.
    • Detections of influenza A(H3N2) have been steadily increasing since mid-January and account for 89% 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 16, the following influenza activity levels were reported (Figure 1):
    • 14 regions reported localized activity: in Man.(1), Ont.(7), Que.(2), N.B.(1), N.S.(2), and Y.T.(1).
    • 22 regions reported sporadic activity: in B.C.(5), Man.(3), Que.(4), N.S.(2), N.B.(6), P.E.I (1) and N.W.T.(1)
    • Two regions: in Man.(1) and N.W.T.(1) reported no activity.



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-16

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 16, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
    • The percentage of tests positive for influenza decreased to 17% in week 16.
    • A total of 1,024 laboratory detections of influenza were reported, of which 85% were influenza A.
    • Influenza A(H3N2) accounted for 89% of subtyped influenza A detections.
    To date this season, 44,970 laboratory-confirmed influenza detections have been reported:
    • 97% have been influenza A.
    • Among the 15,235 influenza A viruses subtyped, 73% 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 36,036 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 2019-16

    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.
    Data for week 14 excludes subtyping results from one jurisdiction due to batch reporting of subtype information. The results for week 14 should be interpreted with caution.
    Figure 2 - Text equivalent Figure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-16

    Figure 3 - Text equivalent
    0-4 6566 1679 213 4674 195 6761 19%
    5-19 4967 1387 416 3164 330 5297 15%
    20-44 6661 1990 536 4135 230 6891 19%
    45-64 6757 1950 549 4258 92 6849 19%
    65+ 10027 1452 2341 6234 211 10238 28%
    Total 34978 8458 4055 22465 1058 36036 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 16, 0.8% 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 2019-16

    Number of Sentinels Reporting in Week 16: 91
    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 16, 1,904 participants reported to FluWatchers, of which 46 (2.4%) reported symptoms of cough and fever (Figure 5).
    Among the 46 participants who reported fever and cough:
    • 13% consulted a healthcare professional;
    • 65% reported days missed from work or school, resulting in a combined total of 92 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-16

    Number of Participants Reporting in Week 16: 1,904
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 16, 21 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (12) and other settings (9). Three new ILI outbreaks were reported: LTCF (2) and schools (1). Among the outbreaks with available subtype information (7), all were associated with influenza A(H3N2).
    To date this season, 753 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 441 (59%) outbreaks were in LTCF, 30 were in schools and daycares, 113 in acute care facilities, and 169 were in other settings.
    • Among the 662 outbreaks for which the influenza type was available, 98% (648) were associated with influenza A.
    • Among the 281 outbreaks for which the influenza A subtype was available, 54% (151) were associated with influenza A(H3N2);
    To date this season, 151 ILI outbreaks have been reported; 85 occurred in LTCF, 61 in schools, one in other settings and four in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-16

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 2,932 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 98.4% (2,886) were associated with influenza A
    • Among the 1,670 cases for which the influenza subtype was available, 1,404 (84%) 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 536 ICU admissions and 165 deaths have been reported.
      • 41% (221) of reported ICU admissions were in adults aged 45-64 years.
      • All but seven ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 383 17 84.04
    5-19 231 15 17.73
    20-44 345 4 12.27
    45-64 748 3 34.51
    65+ 1179 7 97.48
    Total 2886 46
    % 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

    To date this season, 1,217 pediatric hospitalizations have been reported (Figure 7 & 8):
    • 66% of cases were in children under 5 years of age.
    • 95% (1,152) of cases have been associated with influenza A.
    • Among the 358 cases for which the influenza subtype was available, 299 (84%) were associated with A(H1N1)pdm09.
    To date this season, 229 ICU admissions, and 10 deaths have been reported.
    • 59% (135) of ICU admissions were in children under 5 years of age.
    • All but nine 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 2019-16

    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 2019-16

    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, 901 hospitalizations, 105 ICU admissions and 50 deaths have been reported (Figure 9):
    • 840 (93%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (60%) compared to adults <65 years of age (40%).
    • Among the 194 cases for which the influenza subtype was available, 106 (55%) were associated with A(H1N1)pdm09.
    • 89% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 95% 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 2019-16

    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 2,006 influenza viruses (353 A(H3N2), 1,553 A(H1N1) and 100 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    164 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:
    • 20 viruses belonged to genetic group 3C.2a.
    • 139 viruses belonged to subclade 3C.2a1.
    • Four 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):
    • 111 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.
    • 78 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.
    • 71 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 18 viruses belonged to genetic group 3C.2a and 29 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,510 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.
    • 43 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).
    • 16 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.
    • 61 viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
    • 23 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.
    • ...
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  • Pathfinder
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    FluWatch report: March 24, 2019 to March 30, 2019 (week 13)


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    Organization: Public Health Agency of Canada
    Date published: 2019-04-05

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    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.
    • ...
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    FluWatch report: March 17, 2019 to March 23, 2019 (week 12)


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    Organization: Public Health Agency of Canada
    Date published: 2019-03-29

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    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


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    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


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  • Pathfinder
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    FluWatch report: March 3, 2019 to March 9, 2019 (week 10)


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    (PDF format, 894 KB, 9 pages)
    Organization: Public Health Agency of Canada
    Date published: 2019-03-15

    Related Topics



    Overall Summary

    • At the national level, most indicators of influenza activity remained similar, or increased slightly, compared to the previous week.
    • Influenza activity continues to be reported in almost all regions in Canada but is circulating at higher levels in eastern regions.
    • Influenza A(H1N1)pdm09 has been the predominant subtype to date this season.
    • Detections of influenza A(H3N2) have been steadily increasing since mid-January and accounted for 56% of subtyped influenza A detections this week.
    • There is currently very little influenza B circulation compared to previous seasons.


    On this page

    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 10, the following influenza activity levels were reported (Figure 1):
    • 17 regions reported localized activity: in Alta.(1), Ont.(5), Que.(2), N.S.(4), N.B.(3), and N.L.(2).
    • 30 regions reported sporadic activity: in B.C.(5), Alta.(4), Man.(4), Ont.(2), Que.(4), N.B.(3), N.L.(2), P.E.I.(1), Nvt.(3), Y.T.(1) and N.W.T.(1)
    • Three regions: in Man.(1), N.B.(1) and N.W.T.(1) reported no activity.



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-10

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 10, 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 21.3%.
    • A total 1,803 laboratory detections of influenza were reported, of which 96% were influenza A.
    • Influenza A(H3N2) accounted for 56% of subtyped influenza A detections.
    • Detections of influenza A(H3N2) have been steadily increasing, from 93 detections in week 4 (mid-January) to 308 this week.
    To date this season, 36,124 laboratory-confirmed influenza detections have been reported:
    • 98% have been influenza A.
    • Among the 12,329 influenza A viruses subtyped, 85% 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 28,283 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.
    • 60% 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 2019-10

    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 2019-10

    Figure 3 - Text equivalent
    0-4 5829 1617 69 4143 83 5912 21%
    5-19 4104 1337 131 2636 113 4217 15%
    20-44 5506 1802 220 3484 81 5587 20%
    45-64 5531 1723 203 3605 59 5590 20%
    65+ 6816 1241 905 4670 161 6977 25%
    Total 27786 7720 1528 18538 497 28283 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 10, 1.3% 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 2019-10

    Number of Sentinels Reporting in Week 10: 95
    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 10, 2,112 participants reported to FluWatchers, of which 65 (3.1%) reported symptoms of cough and fever (Figure 5).
    Among the 65 participants who reported fever and cough:
    • 20% consulted a healthcare professional;
    • 78% reported days missed from work or school, resulting in a combined total of 134 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-10

    Number of Participants Reporting in Week 10: 2,112
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 10, 30 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (12), acute care facilities (11) and other settings (7).
    To date this season, 540 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 314 (58%) outbreaks were in LTCF, 29 were in schools, 83 in acute care facilities, and 114 were in other settings.
    • Among the 481 outbreaks for which the influenza type was available, 98% (473) were associated with influenza A.
    • Among the 206 outbreaks for which the influenza A subtype was available, 56% (116) were associated with influenza A(H1N1)pdm09;
    To date this season, 119 ILI outbreaks have been reported; 64 occurred in LTCF, 51 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 2019-10

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 2,351 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.1% (2,329) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 429 ICU admissions and 109 deaths have been reported.
      • 43% (185) of reported ICU admissions were in adults aged 45-64 years.
      • All but three ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 333 8 71.64
    5-19 199 6 14.77
    20-44 306 1 10.79
    45-64 635 2 29.27
    65+ 856 5 70.77
    Total 2329 22
    % 99.1% 0.9%
    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 10, 45 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, 1,015 pediatric hospitalizations have been reported (Figure 8):
    • 68% of cases were in children under 5 years of age.
    • 98% (992) of cases have been associated with influenza A.
    • Among the 311 cases for which the influenza subtype was available, 286 (92%) were associated with A(H1N1)pdm09.
    To date this season, 172 ICU admissions, and 10 deaths have been reported.
    • 63% (108) 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 2019-10

    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 2019-10

    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, 694 hospitalizations, 80 ICU admissions and 32 deaths have been reported (Figure 9):
    • 645 (93%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (58%) compared to adults <65 years of age (42%).
    • 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 2019-10

    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,570 influenza viruses (195 A(H3N2), 1,340 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./p>
    Antigenic Characterization:

    Influenza A (H3N2):
    • 68 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.
    • 25 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):
    • 1,302 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.
    • 38 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...ch-9-2019.html


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  • Pathfinder
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    FluWatch report: February 24, 2019 to March 2, 2019 (week 09)


    Download the alternative format
    (PDF format, 883 KB, 9 pages)
    Organization: Public Health Agency of Canada
    Date published: 2019-03-08

    Related Topics



    Overall Summary

    • At the national level, most indicators of influenza activity remained similar, or increased slightly, compared to the previous week.
    • Influenza activity continues to be reported in almost all regions in Canada but is circulating at higher levels in eastern regions.
    • Influenza A(H1N1)pdm09 has been the predominant subtype to date this season.
    • Detections of influenza A(H3N2) have been steadily increasing since mid-January and accounted for 58% of subtyped influenza A detections this week.
    • There is currently very little influenza B circulation compared to previous seasons.


    On this page

    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 09, the following influenza activity levels were reported (Figure 1):
    • 16 regions reported localized activity: in Alta.(1), Ont.(6), Que.(2), N.S.(3), N.L.(2) and N.B.(2).
    • 30 regions reported sporadic activity: in B.C.(5), Alta.(4), Sask.(2), Ont.(1), Que.(4), N.B.(5), N.L.(1), P.E.I.(1), N.S.(1), Nvt.(3), Y.T.(1) and N.W.T.(2)
    • Two regions: in N.L.(1) and Sask.(1) reported no activity.



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-09

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 09, 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 20.1%.
    • A total 1,692 laboratory detections of influenza were reported, of which 96% were influenza A.
    • Influenza A(H3N2) accounted for 58% of subtyped influenza A detections.
    • Detections of influenza A(H3N2) have been steadily increasing, from 93 detections in week 4 (mid-January) to 271 this week.
    To date this season, 34,267 laboratory-confirmed influenza detections have been reported:
    • 98% have been influenza A.
    • Among the 11,749 influenza A viruses subtyped, 87% 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 26,890 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.
    • 61% 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 2019-09

    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 2019-09

    Figure 3 - Text equivalent
    0-4 5671 1594 58 4019 72 5743 21%
    5-19 3892 1321 79 2492 90 3982 15%
    20-44 5286 1743 174 3369 69 5355 20%
    45-64 5307 1653 168 3486 54 5361 20%
    65+ 6292 1173 752 4367 157 6449 24%
    Total 26448 7484 1231 17733 442 26890 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 09, 1.6% 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 2019-09

    Number of Sentinels Reporting in Week 09: 84
    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 09, 2,101 participants reported to FluWatchers, of which 57 (Figure 5).
    Among the 57 participants who reported fever and cough:
    • 16% consulted a healthcare professional;
    • 74% reported days missed from work or school, resulting in a combined total of 118 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-09

    Number of Participants Reporting in Week 09: 2,101
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 09, 37 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (18), acute care facilities (8), schools and daycares (1) and other settings (10). Among the outbreaks with available subtype information (12), 92% (11) were associated with influenza A(H3N2).
    To date this season, 491 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 292 (59%) outbreaks were in LTCF, 28 were in schools, 71 in acute care facilities, and 100 were in other settings.
    • Among the 444 outbreaks for which the influenza type was available, 98% (436) were associated with influenza A.
    • Among the 194 outbreaks for which the influenza A subtype was available, 59% (114) were associated with influenza A(H1N1)pdm09;
    To date this season, 107 ILI outbreaks have been reported; 56 occurred in LTCF, 47 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 2019-09

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 2,214 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.5% (2,202) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 403 ICU admissions and 93 deaths have been reported.
      • 42% (163) of reported ICU admissions were in adults aged 45-64 years.
      • All but two ICU admissions were associated with influenza A.
      • All but one of the deaths were associated with influenza A.
    0-4 323 4 68.70
    5-19 189 2 13.76
    20-44 294 0 10.33
    45-64 610 2 28.12
    65+ 786 4 64.93
    Total 2202 12
    % 99.5% 0.5%
    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 09, 30 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, 964 pediatric hospitalizations have been reported (Figure 8):
    • 69% of cases were in children under 5 years of age.
    • 98% (947) of cases have been associated with influenza A.
    • Among the 301 cases for which the influenza subtype was available, 283 (94%) were associated with A(H1N1)pdm09.
    To date this season, 167 ICU admissions, and 10 deaths have been reported.
    • 63% (106) 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 2019-09

    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 2019-09

    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, 641 hospitalizations, 71 ICU admissions and 25 deaths have been reported (Figure 9):
    • 594 (93%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (58%) compared to adults <65 years of age (42%).
    • 85% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 81% 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 2019-09

    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,495 influenza viruses (174 A(H3N2), 1,289 A(H1N1) and 32 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    87 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:
    • 16 viruses belonged to genetic group 3C.2a.
    • 68 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):
    • 65 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.
    • 22 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.
    • 44 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 15 viruses belonged to genetic group 3C.2a and 11 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,253 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.
    • 36 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.
    • Four 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.
    • ...
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  • Pathfinder
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    FluWatch report: February 17 to 23, 2019 (Week 08)


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    Organization: Public Health Agency of Canada
    Date published: 2019-03-01

    Related Topics



    Overall Summary

    • Influenza activity is past the peak in most regions in western Canada, but continues to circulate at higher levels in eastern regions.
    • At the national level, most indicators of influenza activity remained similar, or increased slightly, compared to the previous week.
    • Influenza A(H1N1)pdm09 continues to be the most common influenza virus circulating in Canada. 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 the A(H1N1)pdm09 component.The recommendation for the A(H3N2) component has been postponed.


    On this page

    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 08, the following influenza activity levels were reported (Figure 1):
    • 17 regions reported localized activity: in Alta.(1), Ont.(5), Que.(4), N.S.(3), N.L.(3) and N.B.(1).
    • 29 regions reported sporadic activity: in B.C.(5), Alta.(4), Man.(4), Ont.(2), Que.(2), N.B.(6), N.L.(1), P.E.I.(1), N.S.(1), Nvt.(2), and N.W.T(1)
    • Three regions: in Man.(1), N.W.T(1), and Nvt.(1) reported no activity.



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-08

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 08, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
    • The percentage of tests positive for influenza was 17.9%.
    • A total 1,535 laboratory detections of influenza were reported, of which 98% were influenza A.
    • Influenza A(H1N1)pdm09 and A(H3N2) accounted for equal proportions of subtyped influenza A detections.
    • Detections of influenza A(H3N2) have been steadily increasing, from 93 detections in week 4 (mid-January) to 199 this week.
    To date this season, 32,429 laboratory-confirmed influenza detections have been reported:
    • 99% have been influenza A.
    • Among the 11,210 influenza A viruses subtyped, 89% 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 25,393 laboratory-confirmed influenza cases (Table 1):
    • 85% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
    • 61% 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 2019-08

    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 2019-08

    Figure 3 - Text equivalent
    0-4 5452 1570 42 3840 62 5514 22%
    5-19 3724 1300 58 2366 70 3794 15%
    20-44 5064 1699 139 3226 55 5119 20%
    45-64 5018 1597 139 3282 49 5067 20%
    65+ 5755 1110 596 4049 144 5899 23%
    Total 25013 7276 974 16763 380 25393 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 08, 1.2% 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 2019-08

    Number of Sentinels Reporting in Week 08: 117
    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 08, 2,131 participants reported to FluWatchers, of which 53 (2.5%) reported symptoms of cough and fever (Figure 5).
    Among the 53 participants who reported fever and cough:
    • 9% consulted a healthcare professional;
    • 74% reported days missed from work or school, resulting in a combined total of 102 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-08

    Number of Participants Reporting in Week 08: 2,131
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 08, 37 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (20), acute care facilities (4), schools and daycares (4) and other settings (9). Two new ILI outbreaks in long-term care facilities were also reported in week 08.
    To date this season, 446 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 269 (60%) outbreaks were in LTCF, 27 were in schools, 61 in acute care facilities, and 89 were in other settings.
    • Among the 408 outbreaks for which the influenza type was available, 99% (402) were associated with influenza A.
    • Among the 177 outbreaks for which the influenza A subtype was available, 63% (112) were associated with influenza A(H1N1)pdm09;
    To date this season, 107 ILI outbreaks have been reported; 56 occurred in LTCF, 47 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 2019-08

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 2,093 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.6% (2,085) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 384 ICU admissions and 93 deaths have been reported.
      • 42% (163) of reported ICU admissions were in adults aged 45-64 years.
      • All the ICU admissions, and all but one of the deaths were associated with influenza A.
    0-4 316 2 66.81
    5-19 179 2 13.04
    20-44 287 0 10.09
    45-64 581 1 26.74
    65+ 722 3 59.59
    Total 2085 8
    % 99.6% 0.4%
    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 08, 43 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, 928 pediatric hospitalizations have been reported (Figure 8):
    • 69% of cases were in children under 5 years of age.
    • 98% (914) of cases have been associated with influenza A.
    • Among the 295 cases for which the influenza subtype was available, 280 (95%) were associated with A(H1N1)pdm09.
    To date this season, 159 ICU admissions, and 10 deaths have been reported.
    • 63% (101) 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 2019-08

    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 2019-08

    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, 590 hospitalizations, 65 ICU admissions and 22 deaths have been reported (Figure 9):
    • 543 (92%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (58%) compared to adults <65 years of age (42%).
    • 84% of hospitalized cases reported more than one type of comorbid condition.
    • The most commonly reported comorbidity was endocrine disorders, which were reported in 80% 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 2019-08

    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,412 influenza viruses (150 A(H3N2), 1,234 A(H1N1) and 28 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    79 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:
    • 15 viruses belonged to genetic group 3C.2a.
    • 63 viruses belonged to subclade 3C.2a1.
    • 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):
    • 55 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.
    • 16 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.
    • 33 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. 15 viruses belonged to genetic group 3C.2a and 11 to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,201 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.
    • 33 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.
    • Two viruses showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
    • 17 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.
    • ...
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  • Pathfinder
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    FluWatch report: February 10 to 16, 2019 (Week 07)


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    Organization: Public Health Agency of Canada
    Date published: 2019-02-22

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    Overall Summary
    • Influenza activity in Canada continues to decline slowly. Influenza activity is past the peak in most regions in western Canada, but continues to circulate in eastern regions.
    • At the national level, most indicators of influenza activity declined in week 07.
    • Influenza A(H1N1)pdm09 continues to be the most common influenza virus circulating in Canada. There is currently very little influenza B circulation compared to previous seasons.

    On this pageInfluenza/Influenza-like Illness Activity (geographic spread)

    During week 07, levels of influenza activity were similar to the previous week. The following influenza activity levels were reported (Figure 1):
    • 15 regions reported localized activity: in Alta.(1), Ont.(6), Que.(2), N.S.(4) and N.B.(2).
    • 32 regions reported sporadic activity: in B.C.(5), Alta.(4), Man.(4), Ont.(1), Que.(4), N.B.(5), N.L.(4), P.E.I.(1), Nvt.(2), N.W.T(1), and Y.T.(1).
    • Three regions: in Man.(1), N.W.T(1), and Nvt.(1) reported no activity.


    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-07

    Figure 1 - Text equivalentLaboratory-Confirmed Influenza Detections

    In week 07, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
    • The percentage of tests positive for influenza was similar to the previous week at 17.9%.
    • A total 1,565 laboratory detections of influenza were reported, of which 98% were influenza A.
    To date this season, 30,981 laboratory-confirmed influenza detections have been reported:
    • 99% have been influenza A.
    • Among the 10,778 influenza A viruses subtyped, 91% 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 24,187 laboratory-confirmed influenza cases (Table 1):
    • 85% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
    • 62% 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 2019-07

    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 equivalentFigure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-07

    Figure 3 - Text equivalent
    0-4 5269 1552 36 3681 54 5323 22%
    5-19 3575 1284 38 2253 63 3638 15%
    20-44 4859 1655 110 3094 49 4908 20%
    45-64 4808 1541 118 3149 48 4856 20%
    65+ 5327 1062 487 3778 135 5462 23%
    Total 23838 7094 789 15955 349 24187 100%
    Table 1 - Note 1UnS: 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 07, 1.1% 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 2019-07

    Number of Sentinels Reporting in Week 07: 81
    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 equivalentParticipatory Syndromic Surveillance

    In week 07, 2,131 participants reported to FluWatchers, of which 57 (2.7%) reported symptoms of cough and fever (Figure 5).
    Among the 57 participants who reported fever and cough:
    • 19% consulted a healthcare professional;
    • 68% reported days missed from work or school, resulting in a combined total of 102 missed days of work or school.
    • 69% reported having been vaccinated for influenza this season.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-07

    Number of Participants Reporting in Week 07: 2,131

    Figure 5 - Text equivalentInfluenza Outbreak Surveillance

    In week 07, 21 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (13), acute care facilities (4), and other settings (4). Four new ILI outbreaks in schools/daycares were also reported in week 07. The number of new outbreaks reported each week continues to decline from the peak in week 01.
    To date this season, 398 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 244 (61%) outbreaks were in LTCF, 23 were in schools, 52 in acute care facilities, and 79 were in other settings.
    • Among the 369 outbreaks for which the influenza type was available 98% (363) were associated with influenza A.
    • Among the 163 outbreaks for which the influenza A subtype was available, 67% (110) were associated with influenza A(H1N1)pdm09;
    To date this season, 94 ILI outbreaks have been reported; 44 occurred in LTCF, 47 in schools, and three in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-07

    Figure 6 - Text equivalentSevere Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 2,004 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.7% (1,997) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 368 ICU admissions and 87 deaths have been reported.
      • 43% (157) of reported ICU admissions were in adults aged 45-64 years.
      • All the ICU admissions, and all but one of the deaths were associated with influenza A.
    0-4 307 2 64.92
    5-19 177 1 12.83
    20-44 274 0 9.63
    45-64 558 1 25.69
    65+ 681 3 56.22
    Total 1997 7
    % 99.7% 0.3%
    Table 2 - Note 1Influenza-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 07, 44 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, 884 pediatric hospitalizations have been reported (Figure 8):
    • 69% of cases were in children under 5 years of age.
    • 99% (874) of cases have been associated with influenza A.
    • Among the 290 cases for which the influenza subtype was available, 276 (95%) were associated with A(H1N1)pdm09.
    To date this season, 147 ICU admissions, and 10 deaths have been reported.
    • 63% (93) of ICU admissions were in children under 5 years of age.
    • All but one 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 2019-07

    The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
    Figure 7 - Text equivalentFigure 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 2019-07

    Figure 8 - Text equivalentAdult 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, 538 hospitalizations, 59 ICU admissions and 18 deaths have been reported (Figure 9):
    • 493 (92%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (57.3%) compared to adults <65 years of age (42.8%).
    • Hospitalizations among adults peaked in week 01 then declined to week 04, and have increased in weeks 05 to 07.
    • Among hospitalized cases with available information (481), the most commonly reported comorbidity was endocrine disorders, which were reported in 78% of hospitalized cases. However, 84% of cases reported more than one type of comorbid condition.
    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 2019-07

    Figure 9 - Text equivalentInfluenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,287 influenza viruses (119 A(H3N2), 1,142 A(H1N1) and 26 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    61 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:
    • 10 viruses belonged to genetic group 3C.2a.
    • 50 viruses belonged to subclade 3C.2a1.
    • 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):
    • 43 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.
    • 15 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.
    • 27 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. Nine viruses belonged to genetic group 3C.2a and nine to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 1,112 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.
    • 30 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).
    • Eight 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.
    • One virus showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
    • 17 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.
    ...
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    FluWatch report: February 3, 2019 to February 9, 2019 (week 06)


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    Organization: Public Health Agency of Canada
    Date published: 2019-02-15

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    Overall Summary
    • Influenza activity in Canada continues to decline slowly. Influenza activity is past the peak in most regions in western Canada, but continues to circulate in eastern regions.
    • At the national level, most indicators of influenza activity declined in week 06.
    • Influenza A(H1N1)pdm09 continues to be the most common influenza virus circulating in Canada. There is currently very little influenza B circulation compared to previous seasons.
    • The higher proportion of laboratory detections, hospitalizations and outbreaks among people in younger age-groups reflects the increased impact of A(H1N1)pdm09 on people under 65 years of age compared to the past two seasons.

    On this pageInfluenza/Influenza-like Illness Activity (geographic spread)

    During week 06, fewer regions reported high levels of activity compared to the previous week. The following influenza activity levels were reported (Figure 1):
    • 16 regions reported localized activity: in Alta.(2), Ont.(6), Que.(3), N.S.(3) and N.B.(2).
    • 34 regions reported sporadic activity: in B.C.(5), Alta.(3), Sask.(3), Man.(4), Que.(4), N.B.(5), N.S.(1), N.L.(3), P.E.I.(1), Nvt.(3), N.W.T(1), and Y.T.(1).
    • Three regions: in Man.(1), N.L.(1), and N.W.T(1) reported no activity.


    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-06

    Figure 1 - Text descriptionLaboratory Confirmed Influenza Detections

    In week 06, the following results were reported from sentinel laboratories across Canada (Figure 2 and Figure 3):
    • The percentage of tests positive for influenza decreased slightly compared to the previous week at 18.1%.
    • A total 1,684 laboratory detections of influenza were reported, of which 98% were influenza A.
    To date this season, 29,374 laboratory-confirmed influenza detections have been reported:
    • 99% have been influenza A.
    • Among the 10,418 influenza A viruses subtyped, 91% 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 22,979 laboratory-confirmed influenza cases (Table 1):
    • 85% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
    • 61% 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 2019-06

    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 descriptionFigure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-06

    Figure 3 - Text description
    0-4 5035 1529 32 3474 47 5082 22%
    5-19 3414 1274 31 2109 56 3470 15%
    20-44 4663 1617 98 2948 41 4704 20%
    45-64 4588 1482 109 2997 44 4632 20%
    65+ 4957 1013 430 3514 134 5091 22%
    Total 22657 6915 700 15042 322 22979 100%
    Table 1 - Note 1UnS: 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 06, 1.1% 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 2018-19-06

    Number of Sentinels Reporting in Week 06: 98
    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 descriptionParticipatory Syndromic Surveillance

    In week 06, 2,207 participants reported to FluWatchers, of which 57 (2.6%) reported symptoms of cough and fever (Figure 5).
    Among the 57 participants who reported fever and cough:
    • 11% consulted a healthcare professional;
    • 82% reported days missed from work or school, resulting in a combined total of 114 missed days of work or school.
    • 69% reported having been vaccinated for influenza this season.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-06

    Number of Participants Reporting in Week 06: 2,207

    Figure 5 - Text descriptionInfluenza Outbreak Surveillance

    In week 06, 27 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (17), acute care facilities (5), and other settings (5). Six new ILI outbreaks in schools/daycares were also reported in week 06. The number of new outbreaks reported each week continues to decline from the peak in week 01.
    To date this season, 357 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 215 (60%) outbreaks were in LTCF, 23 were in schools, 48 in acute care facilities, and 71 were in other settings.
    • Among the 332 outbreaks for which the influenza type was available 98% (327) were associated with influenza A.
    • Among the 149 outbreaks for which the influenza A subtype was available, 71% (106) were associated with influenza A(H1N1)pdm09;
    To date this season, 89 ILI outbreaks have been reported; 43 occurred in LTCF, 43 in schools, and three in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-06

    Figure 6 - Text descriptionSevere Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 1,933 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.7% (1,927) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 356 ICU admissions and 82 deaths have been reported.
      • 44% (156) of reported ICU admissions were in adults aged 45-64 years.
      • All the ICU admissions, and all but one of the deaths were associated with influenza A.
    Table 2 - Note 1Influenza-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
    0-4 302 2 63.87
    5-19 173 0 12.47
    20-44 269 0 9.45
    45-64 526 0 24.17
    65+ 657 4 54.33
    Total 1927 6
    % 99.7% 0.3%
    Pediatric Influenza Hospitalizations and Deaths

    In week 06, 36 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, 845 pediatric hospitalizations have been reported (Figure 8):
    • 69% of cases were in children under 5 years of age.
    • 99% (836) of cases have been associated with influenza A.
    • Among the 285 cases for which the influenza subtype was available, 273 (96%) were associated with A(H1N1)pdm09.
    To date this season, 140 ICU admissions, and 10 deaths have been reported.
    • 63% (86) of ICU admissions were in children under 5 years of age.
    • All but one 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 2019-06

    The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
    Figure 7 - Text descriptionFigure 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 2019-06

    Figure 8 - Text descriptionAdult 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, 481 hospitalizations, 50 ICU admissions and 17 deaths have been reported (Figure 9):
    • 436 (91%) hospitalizations were associated with influenza A.
    • A greater proportion of hospitalizations have been reported among adults ≥65 years of age (57.2%) compared to adults <65 years of age (42.8%).
    • Hospitalizations among adults peaked in week 01 then declined, followed by a plateau in week 03-05, and increased slightly in week 06.
    • Among hospitalized cases with available information (428), the most commonly reported comorbidity was endocrine disorders, which were reported in 87% of hospitalized cases. However, 83% of cases reported more than one type of comorbid condition.
    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 2019-06

    Figure 9 - Text descriptionInfluenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 1,103 influenza viruses (87 A(H3N2), 992 A(H1N1) and 24 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    45 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:
    • Seven viruses belonged to genetic group 3C.2a.
    • 37 viruses belonged to subclade 3C.2a1.
    • 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):
    • 33 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.
    • Nine 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.
    • 22 influenza A(H3N2) viruses characterized belonged to genetic group 3C.2a1. Seven viruses belonged to genetic group 3C.2a and seven to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 966 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.
    • 26 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).
    • Seven 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
    • 17 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.
    • ...
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    FluWatch report: January 27, 2019 to February 2, 2019 (week 05)


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    Organization: Public Health Agency of Canada
    Date published: 2019-02-08

    Related Topics



    Overall Summary

    • Influenza activity in Canada is declining but influenza continues to circulate with eastern regions continuing to report higher levels of influenza activity compared to western regions.
    • At the national level, the influenza season appears to be past the peak of activity, with most indicators showing stable or downward trends in week 05. Influenza A(H1N1)pdm09 continues to be the most common influenza virus circulating in Canada.
    • A report on influenza vaccine coverage in Canada for 2017-18 shows that coverage was low among adults (38%) and highest among seniors (71%). These results are similar to recent seasons.
    • The effectiveness of the influenza vaccine for the 2018-19 season is estimated to be 72% against the predominant circulating strain this season, with significant protection observed in all age groups.


    On this page

    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 05, fewer regions reported high levels of activity compared to the previous week. The following influenza activity levels were reported (Figure 1):
    • 17 regions reported localized activity: in Alta.(1), Ont.(6), Que.(3), N.L.(1), N.S.(3) and N.B.(3).
    • 34 regions reported sporadic activity: in B.C.(5), Alta.(4), Sask.(3), Man.(5), Ont.(1), Que.(3), N.B.(4), N.S.(1), N.L.(3), P.E.I.(1), Nvt.(3) and Y.T.(1).
    • Two regions in N.W.T reported no activity.



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-05

    Figure 1 - Text equivalent Laboratory-Confirmed Influenza Detections

    In week 05, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):
    • The percentage of tests positive for influenza was similar to the previous week at 19.7%.
    • A total 2,002 laboratory detections of influenza were reported, of which 98% were influenza A.
    To date this season, 27,645 laboratory-confirmed influenza detections have been reported:
    • 99% have been influenza A.
    • Among the 10,014 influenza A viruses subtyped, 92% 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 21,728 laboratory-confirmed influenza cases (Table 1):
    • 86% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
    • 62% 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 2019-05

    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 2019-05

    Figure 3 - Text equivalent
    0-4 4775 1493 26 3256 42 4817 22%
    5-19 3242 1251 25 1966 46 3288 15%
    20-44 4450 1563 87 2800 32 4482 21%
    45-64 4367 1418 98 2851 43 4410 20%
    65+ 4609 966 384 3259 122 4731 22%
    Total 21443 6691 620 14132 285 21728 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 05, 1.5% 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 2019-05

    Number of Sentinels Reporting in Week 05: 106
    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 05, 2,196 participants reported to FluWatchers, of which 66 (3.0%) reported symptoms of cough and fever (Figure 5).
    Among the 66 participants who reported fever and cough:
    • 27% consulted a healthcare professional;
    • 83% reported days missed from work or school, resulting in a combined total of 190 missed days of work or school.
    • 68% reported having been vaccinated for influenza this season.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-05

    Number of Participants Reporting in Week 05: 2,196
    Figure 5 - Text equivalent Influenza Outbreak Surveillance

    In week 05, 24 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (16), acute care facilities (3), and other settings (5). Ten new ILI outbreaks in long-term care facilities (1) and schools/daycares (9) were also reported in week 05.
    To date this season, 322 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 193 (60%) outbreaks were in LTCF, 23 were in schools, 42 in acute care facilities, and 64 were in other settings.
    • Among the 301 outbreaks for which the influenza type was available 98% (296) were associated with influenza A.
    • Among the 140 outbreaks for which the influenza A subtype was available:
      • 74% (104) were associated with influenza A(H1N1)pdm09;
      • 26% (36) were associated with A(H3N2),
    To date this season, 82 ILI outbreaks have been reported; 42 occurred in LTCF, 37 in schools, and three in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-05

    Figure 6 - Text equivalent Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 1,833 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.7% (1,828) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    • To date this season 336 ICU admissions and 77 deaths have been reported.
      • 43% (145) of reported ICU admissions were in adults aged 45-64 years.
      • All but one of the reported deaths were associated with influenza A.
    0-4 297 2 62.82
    5-19 166 0 11.96
    20-44 250 0 8.79
    45-64 503 0 23.11
    65+ 612 3 50.55
    Total 1828 5
    % 99.7% 0.3%
    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 05, 56 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, 802 pediatric hospitalizations have been reported (Figure 8):
    • 69.5% of cases were in children under 5 years of age.
    • 99% (795) of cases have been associated with influenza A.
    • Among the 279 cases for which the influenza subtype was available, 270 (97%) were associated with A(H1N1)pdm09.
    To date this season, 135 ICU admissions, and 10 deaths have been reported.
    • 63% (85) of ICU admissions were in children under 5 years of age.
    • All but one 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 2019-05

    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 2019-05

    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, 430 hospitalizations, 47 ICU admissions and 16 deaths have been reported (Figure 9):
    • 388 (90%) hospitalizations were associated with influenza A.
    • A similar proportion of hospitalizations are reported among adults <65 years of age (43.3%) and adults ≥65 years of age (56.7%).
    • Similar to other indicators this season, hospitalizations among adults peaked in week 01, but has been stable over the past three weeks.
    • Among hospitalized cases with available information (367), the most commonly reported comorbidity was endocrine disorders, which were reported in 88% of hospitalized cases. However, 84% of cases reported more than one type of comorbid condition.
    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 2019-05

    Figure 9 - Text equivalent Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 972 influenza viruses (69 A(H3N2), 882 A(H1N1) and 21 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    42 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:
    • Seven viruses belonged to genetic group 3C.2a.
    • 34 viruses belonged to subclade 3C.2a1.
    • 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):
    • 23 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.
    • Four 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.
    • 17 influenza A (H3N2) viruses characterized belonged to genetic group 3C.2a1. Three viruses belonged to genetic group 3C.2a and five to 3C.3a. Sequencing is pending for the remaining isolates.
    Influenza A(H1N1):
    • 861 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.
    • 21 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).
    • Four 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
    • 17 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...ry-2-2019.html


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    FluWatch report: January 20, 2019 to January 26, 2019 (week 04)


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    Organization: Public Health Agency of Canada
    Date published: 2019-02-01

    Related Topics



    Overall Summary

    • Influenza continues to circulate across Canada with eastern regions reporting higher levels of influenza activity compared to western regions.
    • At the national level, the influenza season appears to be past the peak of activity, with most indicators showing stable or downward trends in week 04.
    • Influenza A is the most common influenza virus circulating in Canada, and the majority of these viruses are A(H1N1)pdm09.
    • Based on a recently published Canadian influenza vaccine effectiveness study, mid-season vaccine effectiveness estimates indicate that this year’s flu shot is approximately 72% effective against the predominant circulating strain. Significant protection was observed in all age groups, especially young children who have been disproportionately affected by influenza this season.


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    Influenza/Influenza-like Illness Activity (geographic spread)

    During week 04, the following influenza activity levels were reported (Figure 1):
    • 2 regions reported widespread activity: in Que.(1) and P.E.I.(1).
    • 19 regions reported localized activity: in Alta.(1), Ont.(6), Que.(3), N.L.(1) N.S.(4) and N.B.(4).
    • 31 regions reported sporadic activity: in B.C.(5), Alta.(4), Sask.(3), Man.(5), Que.(3), N.B.(3), N.L.(3), Nvt.(3), N.W.T.(1) and Y.T.(1).
    • One region reported no activity: in N.W.T.(1).



    Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2019-04

    Figure 1 - Text description Laboratory Confirmed Influenza Detections

    In week 04, the following results were reported from sentinel laboratories across Canada (Figure 2):
    • The percentage of tests positive for influenza was similar to the previous week at 20.7%.
    • A total 2,270 laboratory detections of influenza were reported, of which 98% were influenza A.
    To date this season, 25,764 laboratory-confirmed influenza detections have been reported:
    • 99% have been influenza A.
    • Among the 9,479 influenza A viruses subtyped, 93% have been A(H1N1)pdm09.
    • Provincial and territorial differences in influenza type/subtype distribution are observed (Figure 3).
    To date this season, detailed information on age and type/subtype has been received for 20,254 laboratory-confirmed influenza cases (Table 1):
    • 86% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.
    • 62% 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 2019-04

    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 Figure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-04

    Figure 3 - Text description
    0-4 4446 1444 23 2979 34 4480 22%
    5-19 3035 1220 21 1794 40 3075 15%
    20-44 4204 1512 77 2615 28 4232 21%
    45-64 4110 1364 89 2657 39 4149 20%
    65+ 4213 911 338 2964 105 4318 21%
    Total 20008 6451 548 13009 246 20254 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 04, 1.8% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4). The percentage of visits for ILI is within expected levels.
    Figure 4 – Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2018-19-04

    Number of Sentinels Reporting in Week 04: 93
    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 description Participatory Syndromic Surveillance

    In week 04, 2,207 participants reported to FluWatchers, of which 64 (2.9%) reported symptoms of cough and fever (Figure 5).
    Among the 64 participants who reported fever and cough:
    • 25% consulted a healthcare professional;
    • 75% reported days missed from work or school, resulting in a combined total of 147 missed days of work or school.
    Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-04

    Number of Participants Reporting in Week 04: 2,207
    Figure 5 - Text description Influenza Outbreak Surveillance

    In week 04, 27 new laboratory-confirmed influenza outbreaks were reported: long-term care facilities (LTCF) (12), acute care facilities (6), schools/daycares (1) and other settings (8). Fourteen new ILI outbreaks in long-term care facilities (3) and schools/daycares (11) were also reported in week 04.
    To date this season, 296 laboratory-confirmed influenza outbreaks have been reported (Figure 6):
    • 175 outbreaks were in LTCF, 23 were in schools, 39 in acute care facilities, and 59 were in other settings.
    • Among the 278 outbreaks for which the influenza type was available 99% (274) were associated with influenza A.
    • Among the 131 outbreaks for which the influenza A subtype was available:
      • 76% (99) were associated with influenza A(H1N1)pdm09;
      • 24% (32) were associated with A(H3N2),
    To date this season, 72 ILI outbreaks have been reported; 41 occurred in LTCF, 28 in schools, and three in acute care facilities.
    Figure 6 – Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-04

    Figure 6 - Text description Severe Outcomes Influenza Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths
    To date this season, 1,761 influenza-associated hospitalizations have been reported by participating provinces and territoriesFootnote1.
    Hospitalizations (Table 2):
    • 99.7% (1,755) were associated with influenza A
    • The highest estimated rate of hospitalization is among children under 5 years of age.
    Intensive Care Unit (ICU) cases and deaths:
    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
    0-4 290 2 61.35
    5-19 161 0 11.60
    20-44 243 0 8.54
    45-64 483 1 22.24
    65+ 578 3 47.75
    Total 1755 6
    % 99.7% 0.3%
    Pediatric Influenza Hospitalizations and Deaths

    In week 04, 65 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, 747 pediatric hospitalizations have been reported (Figure 8):
    To date this season, 126 ICU admissions, and 10 deaths have been reported.
    Figure 7 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2019-04

    The shaded area represents the maximum and minimum number of cases reported by week from seasons 2010-11 to 2017-18
    Figure 7 - Text description 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 2019-04

    Figure 8 - Text description 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, 373 hospitalizations have been reported (Figure 9):
    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 2019-04

    Figure 9 - Text description Influenza Strain Characterizations

    Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized 785 influenza viruses (66 A(H3N2), 701 A(H1N1) and 18 B) that were received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2):

    42 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:
    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):
    Influenza A(H1N1):
    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).
    • To date this season 319 ICU admissions and 75 deaths have been reported.
      • 43% (137) of reported ICU admissions were in adults aged 45-64 years.
      • All but one of the reported deaths were associated with influenza A.
      • 70% of cases were in children under 5 years of age.
      • 99% (740) of cases have been associated with influenza A.
      • Among the 266 cases for which the influenza subtype was available, 259 (97%) were associated with A(H1N1)pdm09.
      • 63% (80) of ICU admissions were in children under 5 years of age.
      • 99% (125) of 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.
      • 336 (90%) were associated with influenza A.
      • A similar proportion of hospitalizations are reported among adults <65 years of age (45.5%) and adults ≥65 years of age (55.5%).
      • The most commonly reported comorbidity among hospitalized cases was endocrine disorders, which were reported in 70% of hospitalized cases.
      • Seven viruses belonged to genetic group 3C.2a.
      • 34 viruses belonged to subclade 3C.2a1.
      • One isolate could not be sequenced.
      • 20 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.
      • Four 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.
      • 16 influenza A (H3N2) viruses characterized belonged to genetic group 3C.2a1. Two viruses belonged to genetic group 3C.2a and five to 3C.3a. Sequencing is pending for the remaining isolate.
      • 686 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.
      • 15 viruses showed reduced titer with ferret antisera raised against cell culture-propagated A/Michigan/45/2015
      • Three 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
      • 15 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...y-26-2019.html

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