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Canada - FluWatch report: January 1 to January 7, 2023 (week 1)

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  • Canada - FluWatch report: January 1 to January 7, 2023 (week 1)

    FluWatch report: October 30 to November 5, 2022 (week 44)



    Download in PDF format
    (2.4 MB, 11 pages)

    Organization: Public Health Agency of Canada

    Published: 2022-11-14
    Related TopicsWeekly Highlights
    • At the national level, influenza activity has crossed the seasonal threshold, indicating the start of an influenza epidemic. All surveillance indicators are increasing and most are above expected levels typical of this time of year.
    Virologic
    • In week 44, a total of 2,234 laboratory detections (2,231 influenza A and 3 influenza B) were reported.
    • Among subtyped influenza A detections in week 44, 96% (1,149) were influenza A(H3N2) and 4% (44) were influenza A(H1N1).
    • Among detections for which age information was reported in week 44 (1,197), 739 (64%) of detections were in individuals aged 0-19 years old.
    Syndromic
    • The percentage of visits for influenza-like illness (ILI) was 1.2% in week 44. The percentage visits for ILI is above the seasonal average.
    • The percentage of FluWatchers reporting fever and cough was 2.6% in week 44. The percentage of FluWatchers reporting cough and fever is well above levels typical of this time of year.
    Outbreaks
    • From August 28, 2022 to November 5, 2022 (weeks 35 to 44), 35 laboratory-confirmed influenza outbreaks have been reported.
    Severe Outcomes
    • In recent weeks, the IMPACT network has reported a sharp increase in influenza-associated hospitalizations among the pediatric population. In week 44, 78 influenza-associated hospitalizations were reported.
    • In week 44, 99 influenza-associated hospitalizations have been reported from participating provinces and territories.
    On this pageInfluenza/Influenza-like Illness Activity - Geographic Spread


    In week 44, nine regions in four provinces (N.B., Ont., Sask., and Alta.) reported localized activity and 22 regions in eight provinces reported sporadic influenza activity (N.L., P.E.I., N.S., N.B., Que., Ont., Sask. and Alta.) (Figure 1).
    Figure 1 - Map of influenza/ILI activity by province and territory, Canada, week 2022-44
    Number of Regions Reporting in Week 44: 40 out of 53
    Figure 1 - Text descriptionLaboratory-Confirmed Influenza Detections


    In week 44, a total of 2,234 laboratory detections (2,231 influenza A and 3 influenza B) were reported. Influenza activity has crossed the seasonal threshold, indicating the start of an influenza epidemic at the national level.

    The following results were reported from sentinel laboratories across Canada in week 44 (Figures 2 and 3):
    • The weekly percentage of tests positive for influenza increased from 6.3% in week 43 to 11.7% in week 44 and is above expected pre-pandemic levels.
    • Among subtyped influenza A detections, 96% (1,149) were influenza A(H3N2) and 4% (44) were influenza A(H1N1).
    • Among detections for which age information was reported (1,197), 739 (64%) of detections were in individuals aged 0-19 years old.

    To date this season (August 28, 2022 to November 5, 2022):
    • 4,480 influenza detections were reported, of which 99% (4,439) were influenza A and among subtyped influenza A detections (2,394), influenza A(H3N2) accounted for 93% of detections.
    • 2,473 laboratory-confirmed influenza detections with age information were reported, of which 1,439 (58%) were in individuals aged 0-19 years old (Figure 4).

    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, week 2022-35 to 2022-44
    Number of Laboratories Reporting in Week 44: 32 out of 34
    Figure 2 - Text descriptionFigure 3 - Percentage of tests positive in Canada compared to previous seasons, week 2022-35 to 2022-44
    The shaded area represents the maximum and minimum number of influenza tests or percentage of tests positive reported by week from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.

    The epidemic threshold is 5% tests positive for influenza. When it is exceeded, and a minimum of 15 weekly influenza detections are reported, a seasonal influenza epidemic is declared.
    Figure 3 - Text descriptionFigure 4 - Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada, week 2022-35 to 2022-44



    Laboratory data notes:

    Testing for influenza and other respiratory viruses has been influenced by the current COVID-19 pandemic. Changes in laboratory testing practices may affect the comparability of data to previous seasons.

    Due to different testing protocols of laboratories across Canada, some influenza A subtype detection counts may not be included in total influenza A detection counts and percent positivity calculations.
    Figure 4 - Text descriptionSyndromic / Influenza-like Illness Surveillance

    Healthcare Practitioners Sentinel Surveillance


    In week 44, 1.2% of visits to healthcare professionals were due to influenza-like illness (ILI). The percentage of visits for ILI is above average but within levels typical of this time of year.

    Since the beginning of the surveillance season, the percentage of visits for ILI has been within or near expected pre-pandemic levels (Figure 5). ILI symptoms are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus and even SARS-CoV-2, the virus that causes COVID-19.

    This indicator should be interpreted with caution as there have been changes in healthcare seeking behavior of individuals and a smaller number of sentinels reporting compared to previous seasons.
    Figure 5 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2022-35 to 2022-44
    Number of Sentinels Reporting in Week 44: 51



    The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
    Figure 5 - Text descriptionFluWatchers


    In week 44, 10,732 participants reported to FluWatchers, of which 2.6% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever has increased in recent weeks and is well above expected levels typical of this time of year.

    The reports of cough and fever are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, and even SARS-CoV-2, the virus that causes COVID-19. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

    Among the 277 participants who reported cough and fever:
    • 18% consulted a healthcare professional;
    • 80% reported days missed from work or school, resulting in an average of 3.1 missed days from work or school among those 196 participants.

    The Northwest Territories had the highest participation rate this week (58 participants per 100,000 population) and the neighbourhood with postal code, K0A had the highest number of participants (143). See what is happening in your neighbourhood! Downloadable datasets are also available on Open Maps.

    If you are interested in becoming a FluWatcher, sign up today.
    Figure 6 - Percentage of FluWatchers reporting cough and fever, Canada, week 2022-35 to 2022-44
    Number of Participants Reporting in Week 44: 10,732



    The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
    Figure 6 - Text descriptionInfluenza Outbreak Surveillance


    In week 44, 13 laboratory-confirmed influenza outbreaks were reported in Canada (9 in long-term care facilities (LTC), 1 in a school/daycare, and 3 in facilities categorized as 'other'). All outbreaks were due to influenza A. An additional three ILI outbreaks were reported in schools/daycares.
    To date this season (August 28, 2022 to November 5, 2022):
    • 35 laboratory-confirmed influenza outbreaks have been reported
      • 16 were in LTC facilities (46%)
      • 11 were in facilities categorized as 'other' (31%)
      • The remaining outbreaks were in either in acute care facilities (4) or schools/daycares (4)
      • All but one outbreak were due to influenza A
    • 6 ILI outbreaks have been reported
      • All ILI outbreaks have been reported in schools and/or daycares.

    Outbreaks of ILI are not specific to any one respiratory pathogen and can be due influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, and even COVID-19. Many respiratory viruses in addition to the flu commonly circulate during the fall and winter, and can cause clusters of cases with respiratory illness which could be captured as ILI.

    Number of provinces and territoriesFootnote1 reporting in week 44: 10 out of 13
    Figure 7: Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2022-35 to 2022-44

    Figure 7 - Text descriptionInfluenza Severe Outcomes Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths


    In week 44, 99 influenza-associated hospitalizations and five ICU admissions were reported by participating provinces and territoriesFootnote2.

    To date this season 184 influenza-associated hospitalizations were reported (August 28, 2022 to November 5, 2022) by participating provinces and territories
    • 99% of the hospitalizations were associated with influenza A.
    • Of the cases with subtype information (132), 90% were associated with influenza A(H3N2)
    • 34% of the hospitalizations were among individuals 65 years of age and older, followed by those 5 to 19 years of age (22%)

    To date this season, 15 ICU admissions and less than five influenza-associated deaths were reported.

    Number of provinces and territories reporting in week 44: 8 out of 9
    Pediatric Influenza Hospitalizations and Deaths


    In week 44, 78 influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. The number weekly influenza-associated hospitalizations are well above levels typical of this time of year (Figure 7). Children aged 2 to 4yrs and 10 to 16yrs each accounted 27% of the weekly hospitalizations followed by those aged 5-9yrs (24%).

    To date this season (August 28, 2022 to November 5, 2022), 133 pediatric influenza-associated hospitalizations and 17 ICU admissions have been reported.
    Figure 8 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, week 2022-35 to 2022-44

    Figure 8 - Text description
    The shaded area represents the maximum and minimum number of hospitalizations, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
    Influenza Strain Characterization


    Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 13 influenza viruses (12 A(H3N2), 1 A(H1N1)) received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2)


    One influenza A(H3N2) virus did not grow to sufficient hemagglutination titers for antigenic characterization by hemagglutination inhibition (HI) assays. Therefore, NML has performed genetic characterization to determine the genetic group identity of this virus.

    Sequence analysis of the HA gene of the virus showed that it belonged to genetic group 3C.2a1b.2a2.

    A/Darwyn/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine and belongs to genetic group 3C.2a1b.2a2.Antigenic Characterization


    Influenza A(H3N2)
    • 11 influenza A (H3N2) viruses were characterized as antigenically similar to A/Darwyn/6/2021 (H3N2)-like virus with antisera raised against cell-grown A/Darwyn/6/2021 (H3N2)-like virus.
      • A/Darwyn/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine.
    • Of the 11 influenza A (H3N2) viruses characterized, 7 viruses belonged to genetic group 3C.2a1b.2a2. Sequencing is pending for the remaining 4 viruses.

    Influenza A(H1N1)
    • One A(H1N1) virus was characterized as antigenically similar to A/Wisconsin/588/2019-like with ferret antisera produced against cell-propagated A/Wisconsin/588/2019.
      • A/Wisconsin/588/2019 is the influenza A/H1N1 component of the 2022-23 Northern Hemisphere influenza vaccine.
    Antiviral Resistance


    The NML also tests influenza viruses received from Canadian laboratories for antiviral resistance.
    Oseltamivir


    11 influenza viruses (10 A(H3N2) and 1 A(H1N1)) were tested for resistance to oseltamivir and it was found that:
    • All influenza viruses were sensitive to oseltamivir.
    Zanamivir


    11 influenza viruses (10 A(H3N2) and 1 A(H1N1)) were tested for resistance to zanamivir and it was found that:
    • All influenza viruses were sensitive to zanamivir.
    ...

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

  • #2
    FluWatch report: November 13 to November 19, 2022 (week 46)

    Download in PDF format
    (2.47 MB, 12 pages)

    Organization: Public Health Agency of Canada

    Published: 2022-11-25
    Related TopicsWeekly Highlights
    • At the national level, influenza activity has continued to increase steeply as we enter the fourth week of the national influenza epidemic. Most surveillance indicators are increasing and all are above expected levels typical of this time of year.
    Virologic
    • In week 46, a total of 5,891 laboratory detections (5,876 influenza A and 15 influenza B) were reported.
    • Among subtyped influenza A detections in week 46, 97% (2,213) were influenza A(H3N2) and 3% (73) were influenza A(H1N1).
    • Among detections for which age information was reported in week 46 (3,256), 1,605 (49%) of detections were in individuals aged 0-19 years old.
    Syndromic
    • The percentage of visits for influenza-like illness (ILI) was 2.1% in week 46. The percentage visits for ILI is slightly above levels typical of this time of year.
    • The percentage of FluWatchers reporting fever and cough was 2.9% in week 46. The percentage of FluWatchers reporting cough and fever is well above levels typical of this time of year.
    Outbreaks
    • From August 28, 2022 to November 19, 2022 (weeks 35 to 46), 127 laboratory-confirmed influenza outbreaks have been reported.
    Severe Outcomes
    • In recent weeks, the IMPACT network has reported a sharp increase in influenza-associated hospitalizations among the pediatric population. Currently, the weekly number of pediatric hospitalizations being reported is above levels typically seen at the peak of the influenza season. In week 46, 205 influenza-associated hospitalizations were reported.
    • The highest cumulative hospitalization rates are among children under 5 years of age (26/100,000 population) and adults 65 years of age and older 21/100,000 population).
    On this pageInfluenza/Influenza-like Illness Activity - Geographic Spread


    In week 46, four regions in two provinces (Alta., and Man.) reported widespread activity, 16 regions in six provinces (P.E.I., N.S., N.B., Ont., Sask., and Alta.) reported localized activity and 24 regions in ten provinces and territories reported sporadic influenza activity (N.L., N.S., N.B., Que., Ont., Man., Alta., Y.T., N.W.T., and Nvt.) (Figure 1).
    Figure 1 - Map of influenza/ILI activity by province and territory, Canada, week 2022-46
    Number of Regions Reporting in Week 46: 49 out of 53
    Figure 1 - Text descriptionLaboratory-Confirmed Influenza Detections


    In week 46, a total of 5,891 laboratory detections (5,876 influenza A and 15 influenza B) were reported as we progress through the 4th week of the national influenza epidemic.

    The following results were reported from sentinel laboratories across Canada in week 46 (Figures 2 and 3):
    • The weekly percentage of tests positive for influenza increased from 16.0% in week 45 to 19.3% in week 46 and is above expected pre-pandemic levels.
    • Among subtyped influenza A detections, 97% (2,213) were influenza A(H3N2) and 3% (73) were influenza A(H1N1).
    • Among detections for which age information was reported (3,256), 1,605 (49%) of detections were in individuals aged 0-19 years old, a decrease from recent weeks.

    To date this season (August 28, 2022 to November 19, 2022):
    • 14,455 influenza detections were reported, of which 99% (14,384) were influenza A and among subtyped influenza A detections (7,230), influenza A(H3N2) accounted for 96% of detections.
    • 8,541 laboratory-confirmed influenza detections with age information were reported, of which 4,646 (54%) were in individuals aged 0-19 years old (Figure 4).

    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, week 2022-35 to 2022-46
    Number of Laboratories Reporting in Week 46: 34 out of 35
    Figure 2 - Text descriptionFigure 3 - Percentage of tests positive in Canada compared to previous seasons, week 2022-35 to 2022-46
    The shaded area represents the maximum and minimum number of influenza tests or percentage of tests positive reported by week from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.

    The epidemic threshold is 5% tests positive for influenza. When it is exceeded, and a minimum of 15 weekly influenza detections are reported, a seasonal influenza epidemic is declared.
    Figure 3 - Text descriptionFigure 4 - Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada, week 2022-35 to 2022-46



    Laboratory data notes:

    Testing for influenza and other respiratory viruses has been influenced by the current COVID-19 pandemic. Changes in laboratory testing practices may affect the comparability of data to previous seasons.

    Due to different testing protocols of laboratories across Canada, some influenza A subtype detection counts may not be included in total influenza A detection counts and percent positivity calculations.
    Figure 4 - Text descriptionSyndromic / Influenza-like Illness Surveillance

    Healthcare Practitioners Sentinel Surveillance


    In week 46, 2.1% of visits to healthcare professionals were due to influenza-like illness (ILI). The percentage of visits for ILI is slightly above expected levels for this time of year.

    Since the beginning of the surveillance season, the percentage of visits for ILI has been within or near expected pre-pandemic levels (Figure 5). ILI symptoms are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus and SARS-CoV-2, the virus that causes COVID-19.

    This indicator should be interpreted with caution as there have been changes in healthcare seeking behavior of individuals and a smaller number of sentinels reporting compared to previous seasons.
    Figure 5 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2022-35 to 2022-46
    Number of Sentinels Reporting in Week 46: 43



    The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
    Figure 5 - Text descriptionFluWatchers


    In week 46, 10,913 participants reported to FluWatchers, of which 2.9% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever remains well above expected levels typical of this time of year.
    The reports of cough and fever are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, and SARS-CoV-2, the virus that causes COVID-19. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.
    Among the 312 participants who reported cough and fever:
    • 19% consulted a healthcare professional;
    • 82% reported days missed from work or school, resulting in an average of 2.7 missed days from work or school among those 255 participants.
    Manitoba had the highest participation rate this week (44 participants per 100,000 population) and the neighbourhood with postal code, K0A had the highest number of participants (152). See what is happening in your neighbourhood! Downloadable datasets are also available on Open Maps.

    If you are interested in becoming a FluWatcher, sign up today.
    Figure 6 - Percentage of FluWatchers reporting cough and fever, Canada, week 2022-35 to 2022-46
    Number of Participants Reporting in Week 46: 10,913



    The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
    Figure 6 - Text descriptionInfluenza Outbreak Surveillance


    In week 46, 45 laboratory-confirmed influenza outbreaks were reported in Canada (22 in long-term care facilities (LTC), 12 in acute care facilities, and 11 in facilities categorized as ‘other’). All outbreaks were due to influenza A. 25 ILI outbreaks were reported in schools/daycares.

    To date this season (August 28, 2022 to November 19, 2022):
    • 127 laboratory-confirmed influenza outbreaks have been reported
      • 54 were in LTC facilities (43%)
      • 39 were in facilities categorized as ‘other’ (31%)
      • 30 were in acute care facilities (24%)
      • 4 were in schools/daycares (3%)
      • All but one outbreak were due to influenza A
    • 41 ILI outbreaks have been reported
      • All ILI outbreaks have been reported in schools and/or daycares.

    Outbreaks of ILI are not specific to any one respiratory pathogen and can be due influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, COVID-19, or a mixture of viruses. Many respiratory viruses in addition to the flu commonly circulate during the fall and winter, and can cause clusters of cases with respiratory illness which could be captured as ILI.

    Number of provinces and territoriesFootnote1 reporting in week 46: 12 out of 13
    Figure 7: Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2022-35 to 2022-46

    Figure 7 - Text descriptionInfluenza Severe Outcomes Surveillance

    Provincial/Territorial Influenza Hospitalizations and Deaths


    In week 46, 196 influenza-associated hospitalizations and 20 ICU admissions were reported by participating provinces and territoriesFootnote2. This week, 6 influenza-associated deaths were reported.

    To date this season 736 influenza-associated hospitalizations were reported (August 28, 2022 to November 19, 2022) by participating provinces and territories
    • 99% of the hospitalizations were associated with influenza A.
    • Of the cases with subtype information (529), 94% were associated with influenza A(H3N2)
    • The highest cumulative hospitalization rates up to week 46 were among children under 5 years of age (26/100,000 population) and adults 65 years of age and older (21/100,000 population).

    To date this season (August 28, 2022 to November 19, 2022), 64 ICU admissions and 25 influenza-associated deaths were reported.

    Number of provinces and territories reporting in week 46: 9 out of 9
    Figure 8 – Cumulative rates of influenza-associated hospitalizations by age-group and surveillance week, Canada, participating provinces and territories, week 2022-35 to 2022-46

    Figure 8 - Text descriptionPediatric Influenza Hospitalizations and Deaths


    In week 46, 205 influenza-associated pediatric (≤16 years of age) hospitalizations and 25 ICU admissions were reported by the Immunization Monitoring Program Active (IMPACT) network. The number of weekly influenza-associated hospitalizations is well above levels typical of this time of year and is above levels typically seen at the peak of the influenza season (Figure 9). All hospitalisations reported in week 46 except one were associated with influenza A. This week, less than 5 influenza-associated pediatric deaths were reported.

    To date this season (August 28, 2022 to November 19, 2022), 482 pediatric influenza-associated hospitalizations, 58 ICU admissions and less than 5 influenza-associated pediatric deaths have been reported. Children aged between 2-4 years and 5-9 years account for more than 50% of the reported pediatric hospitalizations (Figure 10).
    Figure 9 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, week 2022-35 to 2022-46

    Figure 9 - Text descriptionFigure 10 – Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, week 2022-35 to 2022-46

    Figure 10 - Text descriptionInfluenza Strain Characterization


    Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 28 influenza viruses (23 A(H3N2), 5 A(H1N1)) received from Canadian laboratories.
    Genetic Characterization of Influenza A(H3N2)


    One influenza A(H3N2) virus did not grow to sufficient hemagglutination titers for antigenic characterization by hemagglutination inhibition (HI) assays. Therefore, NML has performed genetic characterization to determine the genetic group identity of this virus.

    Sequence analysis of the HA gene of the virus showed that it belonged to genetic group 3C.2a1b.2a2.

    A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine and belongs to genetic group 3C.2a1b.2a2.
    Antigenic Characterization


    Influenza A(H3N2)
    • 22 influenza A (H3N2) viruses were characterized as antigenically similar to A/Darwin/6/2021 (H3N2)-like virus with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus.
      • A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine.
    • The 22 influenza A (H3N2) viruses characterized belonged to genetic group 3C.2a1b.2a2.

    Influenza A(H1N1)
    • 5 influenza A (H1N1) viruses were characterized as antigenically similar to A/Wisconsin/588/2019-like with ferret antisera produced against cell-propagated A/Wisconsin/588/2019.
      • A/Wisconsin/588/2019 is the influenza A/H1N1 component of the 2022-23 Northern Hemisphere influenza vaccine.
    Antiviral Resistance


    The NML also tests influenza viruses received from Canadian laboratories for antiviral resistance.
    Oseltamivir


    16 influenza viruses (15 A(H3N2) and 1 A(H1N1)) were tested for resistance to oseltamivir and it was found that:
    • All influenza viruses were sensitive to oseltamivir.
    Zanamivir


    16 influenza viruses (15 A(H3N2) and 1 A(H1N1)) were tested for resistance to zanamivir and it was found that:
    • All influenza viruses were sensitive to zanamivir.
    ...

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

    Comment


    • #3
      FluWatch report: November 20 to November 26, 2022 (week 47)

      Download in PDF format
      (2.37 MB, 12 pages)

      Organization: Public Health Agency of Canada

      Published: 2022-12-02
      Related TopicsWeekly Highlights
      • At the national level, influenza activity has continued to increase steeply as we enter the fifth week of the national influenza epidemic. All surveillance indicators are increasing and all are above expected levels typical of this time of year.
      Virologic
      • In week 47, a total of 8,242 laboratory detections (8,226 influenza A and 16 influenza B) were reported.
      • Among subtyped influenza A detections in week 47, 95% (2,214) were influenza A(H3N2) and 5% (119) were influenza A(H1N1).
      • Among detections for which age information was reported in week 47 (5,096), 2,339 (46%) of detections were in individuals aged 0-19 years old.
      Syndromic
      • The percentage of visits for influenza-like illness (ILI) was 3.1% in week 47. The percentage visits for ILI is above levels typical of this time of year.
      • The percentage of FluWatchers reporting fever and cough was 3.1% in week 47. The percentage of FluWatchers reporting cough and fever is above levels typical of this time of year.
      Outbreaks
      • From August 28, 2022 to November 26, 2022 (weeks 35 to 47), 198 laboratory-confirmed influenza outbreaks have been reported.
      Severe Outcomes
      • The IMPACT network continues to report elevated weekly numbers of influenza-associated hospitalizations among the pediatric population. Currently, the weekly number of pediatric hospitalizations being reported is above levels typically seen at the peak of the influenza season. In week 47, 223 influenza-associated hospitalizations were reported.
      • The highest cumulative hospitalization rates are among children under 5 years of age (41/100,000 population) and adults 65 years of age and older 33/100,000 population).
      On this pageInfluenza/Influenza-like Illness Activity - Geographic Spread


      In week 47, almost all regions in Canada reported influenza activity with six regions in three provinces (P.E.I., Alta., and B.C.) reporting widespread activity (Figure 1).
      Figure 1 - Map of influenza/ILI activity by province and territory, Canada, week 2022-46
      Number of Regions Reporting in Week 47: 53 out of 53
      Figure 1 - Text descriptionLaboratory-Confirmed Influenza Detections


      In week 47, a total of 8,242 laboratory detections (8,226 influenza A and 16 influenza B) were reported.

      The following results were reported from sentinel laboratories across Canada in week 47 (Figures 2 and 3):
      • The weekly percentage of tests positive for influenza increased from 19.9% in week 46 to 23.1% in week 47 and remains above expected pre-pandemic levels.
      • Among subtyped influenza A detections, 95% (2,214) were influenza A(H3N2) and 5% (119) were influenza A(H1N1).
      • Among detections for which age information was reported (5,096), 2,339 (46%) of detections were in individuals aged 0-19 years old. The proportion of detections among individuals aged 0-19 years old has been slowly decreasing in recent weeks.

      To date this season (August 28, 2022 to November 26, 2022):
      • 23,294 influenza detections were reported, of which 99% (23,206) were influenza A and among subtyped influenza A detections (10,267), influenza A(H3N2) accounted for 96% of detections.
      • 14,385 laboratory-confirmed influenza detections with age information were reported, of which 7,302 (51%) were in individuals aged 0-19 years old (Figure 4).

      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, week 2022-35 to 2022-47
      Number of Laboratories Reporting in Week 47: 33 out of 35
      Figure 2 - Text descriptionFigure 3 - Percentage of tests positive in Canada compared to previous seasons, week 2022-35 to 2022-47
      The shaded area represents the maximum and minimum number of influenza tests or percentage of tests positive reported by week from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.

      The epidemic threshold is 5% tests positive for influenza. When it is exceeded, and a minimum of 15 weekly influenza detections are reported, a seasonal influenza epidemic is declared.
      Figure 3 - Text descriptionFigure 4 - Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada, week 2022-35 to 2022-47



      Laboratory data notes:

      Testing for influenza and other respiratory viruses has been influenced by the current COVID-19 pandemic. Changes in laboratory testing practices may affect the comparability of data to previous seasons.

      Due to different testing protocols of laboratories across Canada, some influenza A subtype detection counts may not be included in total influenza A detection counts and percent positivity calculations.
      Figure 4 - Text descriptionSyndromic / Influenza-like Illness Surveillance

      Healthcare Practitioners Sentinel Surveillance


      In week 47, 3.1% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 5). The percentage of visits for ILI is above expected levels for this time of year.

      ILI symptoms are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus and SARS-CoV-2, the virus that causes COVID-19.

      This indicator should be interpreted with caution as there have been changes in healthcare seeking behavior of individuals and a smaller number of sentinels reporting compared to previous seasons.
      Figure 5 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2022-35 to 2022-47
      Number of Sentinels Reporting in Week 47: 37



      The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
      Figure 5 - Text descriptionFluWatchers


      In week 47, 10,718 participants reported to FluWatchers, of which 3.1% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever remains above expected levels typical of this time of year.

      The reports of cough and fever are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, and SARS-CoV-2, the virus that causes COVID-19. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

      Among the 330 participants who reported cough and fever:
      • 18% consulted a healthcare professional;
      • 81% reported days missed from work or school, resulting in an average of 2.9 missed days from work or school among those 267 participants.
      The Northwest Territories had the highest participation rate this week (53 participants per 100,000 population) and the neighbourhood with postal code, K0A had the highest number of participants (147). See what is happening in your neighbourhood! Downloadable datasets are also available on Open Maps.

      If you are interested in becoming a FluWatcher, sign up today.
      Figure 6 - Percentage of FluWatchers reporting cough and fever, Canada, week 2022-35 to 2022-47
      Number of Participants Reporting in Week 47: 10,718



      The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
      Figure 6 - Text descriptionInfluenza Outbreak Surveillance


      In week 47, 44 laboratory-confirmed influenza outbreaks were reported in Canada (22 in long-term care facilities (LTC), 12 in facilities categorized as ‘other’, and 10 in acute care facilities). All outbreaks were due to influenza A. 71 ILI outbreaks were reported in schools/daycares.

      To date this season (August 28, 2022 to November 26, 2022):
      • 198 laboratory-confirmed influenza outbreaks have been reported
        • 89 were in LTC facilities (45%)
        • 62 were in facilities categorized as ‘other’ (31%)
        • 43 were in acute care facilities (22%)
        • 4 were in schools/daycares (3%)
        • All but one outbreak was due to influenza A
      • 113 ILI outbreaks have been reported
        • All ILI outbreaks have been reported in schools and/or daycares.

      Outbreaks of ILI are not specific to any one respiratory pathogen and can be due influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, COVID-19, or a mixture of viruses. Many respiratory viruses in addition to the flu commonly circulate during the fall and winter, and can cause clusters of cases with respiratory illness which could be captured as ILI.

      Number of provinces and territoriesFootnote1 reporting in week 47: 12 out of 13
      Figure 7: Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2022-35 to 2022-47

      Figure 7 - Text descriptionInfluenza Severe Outcomes Surveillance

      Provincial/Territorial Influenza Hospitalizations and Deaths


      In week 47, 221 influenza-associated hospitalizations and 26 ICU admissions were reported by participating provinces and territoriesFootnote2. This week, less than 5 influenza-associated deaths were reported.

      To date this season 1,152 influenza-associated hospitalizations were reported (August 28, 2022 to November 26, 2022) by participating provinces and territories
      • 99% of the hospitalizations were associated with influenza A.
      • Of the cases with subtype information (781), 94% were associated with influenza A(H3N2)
      • The highest cumulative hospitalization rates up to week 47 were among children under 5 years of age (41/100,000 population) and adults 65 years of age and older (33/100,000 population).

      To date this season (August 28, 2022 to November 26, 2022), 109 ICU admissions and 36 influenza-associated deaths were reported.

      Number of provinces and territories reporting in week 47: 9 out of 9
      Figure 8 – Cumulative rates of influenza-associated hospitalizations by age-group and surveillance week, Canada, participating provinces and territories, week 2022-35 to 2022-47

      Figure 8 - Text descriptionPediatric Influenza Hospitalizations and Deaths


      In week 47, 223 influenza-associated pediatric (≤16 years of age) hospitalizations and 37 ICU admissions were reported by the Immunization Monitoring Program Active (IMPACT) network. The number of weekly influenza-associated hospitalizations is well above levels typical of this time of year and is above levels typically seen at the peak of the influenza season (Figure 9). All hospitalisations reported in week 47 were associated with influenza A. This week, less than 5 influenza-associated pediatric deaths were reported.

      To date this season (August 28, 2022 to November 26, 2022), 707 pediatric influenza-associated hospitalizations, 95 ICU admissions and less than 5 influenza-associated pediatric deaths have been reported. Children aged between 2-4 years and 5-9 years account for more than 50% of the reported pediatric hospitalizations (Figure 10).
      Figure 9 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, week 2022-35 to 2022-47

      Figure 9 - Text descriptionFigure 10 – Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, week 2022-35 to 2022-47

      Figure 10 - Text descriptionInfluenza Strain Characterization


      Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 44 influenza viruses (37 A(H3N2), 7 A(H1N1)) received from Canadian laboratories.
      Genetic Characterization of Influenza A(H3N2)


      One influenza A(H3N2) virus did not grow to sufficient hemagglutination titers for antigenic characterization by hemagglutination inhibition (HI) assays. Therefore, NML has performed genetic characterization to determine the genetic group identity of this virus.

      Sequence analysis of the HA gene of the virus showed that it belonged to genetic group 3C.2a1b.2a2.

      A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine and belongs to genetic group 3C.2a1b.2a2.
      Antigenic Characterization


      Influenza A(H3N2)
      • 36 influenza A (H3N2) viruses were characterized as antigenically similar to A/Darwin/6/2021 (H3N2)-like virus with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus.
        • A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine.
      • Of the 36 influenza A (H3N2) viruses characterized, 22 belonged to genetic group 3C.2a1b.2a2. Sequences are pending for the remaining viruses.

      Influenza A(H1N1)
      • 7 influenza A (H1N1) viruses were characterized as antigenically similar to A/Wisconsin/588/2019-like with ferret antisera produced against cell-propagated A/Wisconsin/588/2019.
        • A/Wisconsin/588/2019 is the influenza A/H1N1 component of the 2022-23 Northern Hemisphere influenza vaccine.
      Antiviral Resistance


      The NML also tests influenza viruses received from Canadian laboratories for antiviral resistance.
      Oseltamivir


      40 influenza viruses (33 A(H3N2) and 7 A(H1N1)) were tested for resistance to oseltamivir and it was found that:
      • All influenza viruses were sensitive to oseltamivir.
      Zanamivir


      40 influenza viruses (33 A(H3N2) and 7 A(H1N1)) were tested for resistance to zanamivir and it was found that:
      • All influenza viruses were sensitive to zanamivir.
      ...

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

      Comment


      • #4
        FluWatch report: January 1 to January 7, 2023 (week 1)

        Download in PDF format
        (2.50 MB, 12 pages)

        Organization: Public Health Agency of Canada

        Published: 2023-01-13
        Related TopicsWeekly Highlights
        • At the national level, influenza continues to circulate but has declined sharply from the peak that occurred in week 47 (end of November) and is now below expected pre-pandemic levels. All surveillance indicators are decreasing and almost all indicators are within expected levels typical of this time of year.
        Virologic
        • In week 1, a total of 1,749 laboratory detections (1,721 influenza A and 28 influenza B) were reported.
        • Among subtyped influenza A detections in week 1, 77% (266) were influenza A(H3N2) and 23% (80) were influenza A(H1N1).
        • Among detections for which age information was reported in week 1 (1,181), 48% (561) of detections were in individuals aged 65+ years old, an increase from 40% (784) in week 52.
        Syndromic
        • The percentage of visits for influenza-like illness (ILI) was 1.7% in week 1. The percentage visits for ILI is slightly below levels typical of this time of year.
        • The percentage of FluWatchers reporting fever and cough was 1.7% in week 1. The percentage of FluWatchers reporting cough and fever is below seasonal levels.
        Outbreaks
        • From August 28, 2022 to January 7, 2023 (weeks 35 to 1), 572 laboratory-confirmed influenza outbreaks have been reported (16 new laboratory-confirmed influenza outbreaks notified in week 1, 11 of these in long-term care facilities (LTCF)).
        Severe Outcomes
        • The weekly number of influenza-associated hospitalizations among the pediatric population reported by the IMPACT network has declined sharply from the peak that occurred in week 48 and is within levels typical of this time of year. In week 1, 30 influenza-associated hospitalizations were reported.
        • The highest cumulative hospitalization rate up to week 1 is among adults 65 years of age and older (120/100,000 population) and children under 5 years of age (116/100,000 population).
        On this pageInfluenza/Influenza-like Illness Activity - Geographic Spread


        In week 1, almost all regions in Canada reported either sporadic or localized influenza activity (Figure 1).
        Figure 1 - Map of influenza/ILI activity by province and territory, Canada, week 2023-01
        Number of Regions Reporting in week 1: 53 out of 53
        Figure 1 - Text descriptionLaboratory-Confirmed Influenza Detections


        In week 1, the weekly percentage of tests positive for influenza has decreased from the previous week (8.0% in week 52 to 4.6% in week 1) to below expected pre-pandemic levels, and is approaching interseasonal levels.

        The following results were reported from sentinel laboratories across Canada in week 1 (Figures 2 and 3):
        • A total of 1,749 laboratory detections (1,721 influenza A and 28 influenza B) were reported.
        • Among subtyped influenza A detections, 77% (266) were influenza A(H3N2) and 23% (80) were influenza A(H1N1).
        • Among detections for which age information was reported (1,181), 561 (48%) of detections were in individuals aged 65+ years old. The proportion among adults, particularly seniors aged 65+, has increased (from 40% in week 52), whereas the proportion of detections among individuals aged 0-19 years old has decreased (25% in week 52 to 19% in week 1).

        To date this season (August 28, 2022 to January 7, 2023):
        • 62,904 influenza detections were reported, of which 99% (62,670) were influenza A and among subtyped influenza A detections (19,729), influenza A(H3N2) accounted for 94% of detections.
        • 40,134 laboratory-confirmed influenza detections with age information were reported, of which 16,524 (41%) were in individuals aged 0-19 years old (Figure 4).

        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, week 2022-35 to 2023-01
        Number of Laboratories Reporting in Week 1: 33 out of 35
        Figure 2 - Text descriptionFigure 3 - Percentage of tests positive in Canada compared to previous seasons, week 2022-35 to 2023-01
        The shaded area represents the maximum and minimum number of influenza tests or percentage of tests positive reported by week from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.

        The epidemic threshold is 5% tests positive for influenza. When it is exceeded, and a minimum of 15 weekly influenza detections are reported, a seasonal influenza epidemic is declared.
        Figure 3 - Text descriptionFigure 4 - Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada, week 2022-35 to 2023-01



        Laboratory data notes:

        Testing for influenza and other respiratory viruses has been influenced by the current COVID-19 pandemic. Changes in laboratory testing practices may affect the comparability of data to previous seasons.

        Due to different testing protocols of laboratories across Canada, some influenza A subtype detection counts may not be included in total influenza A detection counts and percent positivity calculations.
        Figure 4 - Text descriptionSyndromic / Influenza-like Illness Surveillance

        Healthcare Practitioners Sentinel Surveillance


        In week 1, 1.7% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 5). The percentage of visits for ILI is slightly below expected levels for this time of year.

        ILI symptoms are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus and SARS-CoV-2, the virus that causes COVID-19. This makes the percentage of visits for ILI an important indicator of overall respiratory illness morbidity in the community in the presence of co-circulating viruses.

        This indicator should be interpreted with caution as there have been changes in healthcare seeking behavior of individuals and a smaller number of sentinels reporting compared to previous seasons.
        Figure 5 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2022-35 to 2023-01
        Number of Sentinels Reporting in Week 1: 35



        The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
        Figure 5 - Text descriptionFluWatchers


        In week 1, 10,736 participants reported to FluWatchers, of which 1.7% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever is below seasonal levels.

        The reports of cough and fever are not specific to any one respiratory pathogen and can be due to influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, and SARS-CoV-2, the virus that causes COVID-19. This makes the proportion of individuals reporting cough and fever an important indicator of overall respiratory illness activity in the community in the presence of co-circulating viruses.

        FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

        Among the 178 participants who reported cough and fever:
        • 24% consulted a healthcare professional;
        • 71% reported days missed from work or school, resulting in an average of 2.8 missed days from work or school among those 126 participants.

        The neighbourhood with postal code, K0A had the highest number of participants (142). See what is happening in your neighbourhood! Downloadable datasets are also available on Open Maps.

        If you are interested in becoming a FluWatcher, sign up today.
        Figure 6 - Percentage of FluWatchers reporting cough and fever, Canada, week 2022-35 to 2023-01
        Number of Participants Reporting in Week 1: 10,736



        The shaded area represents the maximum and minimum percentage of percentage of participants reporting cough and fever by week, from seasons 2014-2015 to 2019-2020. Data from week 11 of the 2019-2020 season onwards are excluded from the historical comparison due to the COVID-19 pandemic.
        Figure 6 - Text descriptionInfluenza Outbreak Surveillance


        In week 1, 16 laboratory-confirmed influenza outbreaks were reported in Canada (11 in long-term care facilities (LTC), 3 in facilities categorized as 'other', and 2 in acute care facilities). All outbreaks were due to influenza A.

        To date this season (August 28, 2022 to January 7, 2023):
        • 572 laboratory-confirmed influenza outbreaks have been reported
          • 316 were in LTC facilities (55%)
          • 156 were in facilities categorized as 'other' (27%)
          • 89 were in acute care facilities (16%)
          • 7 were in remote and/or isolated communities (1%)
          • 4 were in schools/daycares (<1%)
          • All but one outbreak was due to influenza A
        • 231 ILI outbreaks have been reported
          • All but 3 ILI outbreaks have been reported in schools and/or daycares.

        Outbreaks of ILI are not specific to any one respiratory pathogen and can be due influenza, or other respiratory viruses, including respiratory syncytial virus, rhinovirus, COVID-19, or a mixture of viruses. Many respiratory viruses in addition to the flu commonly circulate during the fall and winter, and can cause clusters of cases with respiratory illness which could be captured as ILI.

        Number of provinces and territoriesFootnote1 reporting in Week 1: 13 out of 13
        Figure 7: Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2022-35 to 2023-01

        Figure 7 - Text descriptionInfluenza Severe Outcomes Surveillance

        Provincial/Territorial Influenza Hospitalizations and Deaths


        In week 1, 87 influenza-associated hospitalizations and 4 ICU admissions were reported by participating provinces and territoriesFootnote2. This week, 5 influenza-associated deaths were reported.

        To date this season 3,690 influenza-associated hospitalizations were reported (August 28, 2022 to January 7, 2023) by participating provinces and territories:
        • >99% of the hospitalizations were associated with influenza A.
        • Of the cases with subtype information (1,906), 91% were associated with influenza A(H3N2)
        • The highest cumulative hospitalization rates up to week 1 were among adults 65 years of age and older (120/100,000 population) and children under 5 years of age (116/100,000 population).

        To date this season (August 28, 2022 to January 7, 2023), 311 ICU admissions and 218 influenza-associated deaths were reported.

        Number of provinces and territories reporting in Week 1: 9 out of 9
        Figure 8 – Cumulative rates of influenza-associated hospitalizations by age-group and surveillance week, Canada, participating provinces and territories, week 2022-35 to 2023-01

        Figure 8 - Text descriptionPediatric Influenza Hospitalizations and Deaths


        In week 1, 30 influenza-associated pediatric (≤16 years of age) hospitalizations and 3 ICU admissions were reported by the Immunization Monitoring Program Active (IMPACT) network. The number of weekly influenza-associated hospitalizations is within levels typical of this time of year (Figure 9). All but one hospitalisation reported in week 1 were associated with influenza A. This week, no influenza-associated pediatric deaths were reported.

        To date this season (August 28, 2022 to January 7, 2023):
        • 1,534 pediatric influenza-associated hospitalizations have been reported.
        • Children aged between 2-4 years and 5-9 years account for more than 55% of the reported pediatric hospitalizations (Figure 10).
        • 188 ICU admissions were reported; children aged between 2-4 years and 5-9 years account for more than 50% of the reported pediatric ICU admissions.
        • 7 influenza-associated pediatric deaths have been reported.
        Figure 9 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, week 2022-35 to 2023-01

        Figure 9 - Text descriptionFigure 10 – Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, week 2022-35 to 2023-01

        Figure 10 - Text descriptionInfluenza Strain Characterization


        Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 238 influenza viruses (219 A(H3N2), 19 A(H1N1)) received from Canadian laboratories.
        Genetic Characterization of Influenza A(H3N2)


        Three influenza A(H3N2) viruses did not grow to sufficient hemagglutination titers for antigenic characterization by hemagglutination inhibition (HI) assays. Therefore, NML has performed genetic characterization to determine the genetic group identity of these viruses.

        Sequence analysis of the HA genes of the viruses showed that they belonged to genetic group 3C.2a1b.2a2.

        A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine and belongs to genetic group 3C.2a1b.2a2.
        Antigenic Characterization


        Influenza A(H3N2)
        • Of the 216 influenza A (H3N2) viruses characterized, 213 were characterized as antigenically similar to A/Darwin/6/2021 (H3N2)-like virus with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus. Three viruses showed reduced titer with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus.
          • A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine.
        • Of the 216 influenza A (H3N2) viruses characterized, 189 belonged to genetic group 3C.2a1b.2a2. Sequences are pending for the remaining viruses.

        Influenza A(H1N1)
        • 19 influenza A (H1N1) viruses were characterized as antigenically similar to A/Wisconsin/588/2019-like with ferret antisera produced against cell-propagated A/Wisconsin/588/2019.
          • A/Wisconsin/588/2019 is the influenza A/H1N1 component of the 2022-23 Northern Hemisphere influenza vaccine.
        Antiviral Resistance


        The NML also tests influenza viruses received from Canadian laboratories for antiviral resistance.
        Oseltamivir


        175 influenza viruses (160 A(H3N2) and 15 A(H1N1)) were tested for resistance to oseltamivir and it was found that:
        • All influenza viruses were sensitive to oseltamivir.
        Zanamivir


        175 influenza viruses (160 A(H3N2) and 15 A(H1N1)) were tested for resistance to zanamivir and it was found that:
        • All influenza viruses were sensitive to zanamivir.
        ...

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

        Comment

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