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Canada FluWatch Weekly Reports 2018-2019 Season Week 20

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

[FONT=&quot]
pub-eng.jpg

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Organization: Public Health Agency of Canada
Date published: 2019-05-17

Related Topics[/FONT]

[FONT=&quot]Overall Summary[/FONT]
  • [FONT=&quot]Influenza activity continues to decline overall.[/FONT]
  • [FONT=&quot]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).[/FONT]
  • [FONT=&quot]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.[/FONT]
[FONT=&quot]On this page[/FONT]


[FONT=&quot]Influenza/Influenza-like Illness Activity (geographic spread)

During week 19, the following influenza activity levels were reported (Figure 1):[/FONT]
  • [FONT=&quot]7 regions reported localized activity: in Ont.(4), Que.(3).[/FONT]
  • [FONT=&quot]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)[/FONT]
  • [FONT=&quot]12 regions in 9 different provinces and territories reported no activity.[/FONT]
[FONT=&quot]Figure 1 ? Map of overall influenza/ILI activity by province and territory, Canada, week 2019-19

fig1-eng.jpg
Figure 1 - Text equivalentLaboratory-Confirmed Influenza Detections

In week 19, the following results were reported from sentinel laboratories across (Figures 2 and 3):[/FONT]
  • [FONT=&quot]The percentage of tests positive for influenza increased slightly from 11% to 12% in week 19.[/FONT]
  • [FONT=&quot]A total of 592 laboratory detections of influenza were reported, of which 76% were influenza A.[/FONT]
  • [FONT=&quot]Influenza A(H3N2) accounted for 83% of subtyped influenza A detections.[/FONT]
[FONT=&quot]To date this season, 47,143 laboratory-confirmed influenza detections have been reported:[/FONT]
  • [FONT=&quot]96% have been influenza A.[/FONT]
  • [FONT=&quot]Among the 15,938 influenza A viruses subtyped, 71% have been A(H1N1)pdm09.[/FONT]
  • [FONT=&quot]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.[/FONT]
[FONT=&quot]To date this season, detailed information on age and type/subtype has been received for 37,844 laboratory-confirmed influenza cases (Table 1):[/FONT]
  • [FONT=&quot]83% of all influenza A(H1N1)pdm09 detections have been reported in individuals younger than 65 years of age.[/FONT]
  • [FONT=&quot]58% of all influenza A(H3N2) detections have been reported in adults 65 years of age and older.[/FONT]
[FONT=&quot]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

fig2-eng.jpg
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

fig3-eng.jpg
Figure 3 - Text equivalent[/FONT] [TABLE="class: table table-striped table-bordered table-hover table-condensed, width: 1140"]
[TR]
[/TR]
[TR]
[/TR]
[TR]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]0-4[/FONT][/TD]
[TD][FONT=&quot]6707[/FONT][/TD]
[TD][FONT=&quot]1689[/FONT][/TD]
[TD][FONT=&quot]248[/FONT][/TD]
[TD][FONT=&quot]4770[/FONT][/TD]
[TD][FONT=&quot]286[/FONT][/TD]
[TD][FONT=&quot]6993[/FONT][/TD]
[TD][FONT=&quot]18%[/FONT][/TD]
[/TR]
[TR]
[TD][FONT=&quot]5-19[/FONT][/TD]
[TD][FONT=&quot]5127[/FONT][/TD]
[TD][FONT=&quot]1389[/FONT][/TD]
[TD][FONT=&quot]471[/FONT][/TD]
[TD][FONT=&quot]3267[/FONT][/TD]
[TD][FONT=&quot]482[/FONT][/TD]
[TD][FONT=&quot]5609[/FONT][/TD]
[TD][FONT=&quot]15%[/FONT][/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]20-44[/FONT][/TD]
[TD][FONT=&quot]6847[/FONT][/TD]
[TD][FONT=&quot]2012[/FONT][/TD]
[TD][FONT=&quot]596[/FONT][/TD]
[TD][FONT=&quot]4239[/FONT][/TD]
[TD][FONT=&quot]308[/FONT][/TD]
[TD][FONT=&quot]7155[/FONT][/TD]
[TD][FONT=&quot]19%[/FONT][/TD]
[/TR]
[TR]
[TD][FONT=&quot]45-64[/FONT][/TD]
[TD][FONT=&quot]6964[/FONT][/TD]
[TD][FONT=&quot]1963[/FONT][/TD]
[TD][FONT=&quot]632[/FONT][/TD]
[TD][FONT=&quot]4369[/FONT][/TD]
[TD][FONT=&quot]115[/FONT][/TD]
[TD][FONT=&quot]7079[/FONT][/TD]
[TD][FONT=&quot]19%[/FONT][/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]65+[/FONT][/TD]
[TD][FONT=&quot]10761[/FONT][/TD]
[TD][FONT=&quot]1480[/FONT][/TD]
[TD][FONT=&quot]2667[/FONT][/TD]
[TD][FONT=&quot]6614[/FONT][/TD]
[TD][FONT=&quot]247[/FONT][/TD]
[TD][FONT=&quot]11008[/FONT][/TD]
[TD][FONT=&quot]29%[/FONT][/TD]
[/TR]
[TR]
[TD][FONT=&quot]Total[/FONT][/TD]
[TD][FONT=&quot]36406[/FONT][/TD]
[TD][FONT=&quot]8533[/FONT][/TD]
[TD][FONT=&quot]4614[/FONT][/TD]
[TD][FONT=&quot]23259[/FONT][/TD]
[TD][FONT=&quot]1438[/FONT][/TD]
[TD][FONT=&quot]37844[/FONT][/TD]
[TD][FONT=&quot]100%[/FONT][/TD]
[/TR]
[TR]
[TD="colspan: 8"][FONT=&quot]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.[/FONT][/TD]
[/TR]
[/TABLE]
[FONT=&quot]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
fig4-eng.jpg
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
fig5-eng.jpg

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):[/FONT]
  • [FONT=&quot]496 (59%) outbreaks were in LTCF, 30 were in schools and daycares, 120 in acute care facilities, and 192 were in other settings.[/FONT]
  • [FONT=&quot]Among the 752 outbreaks for which the influenza type was available, 98% (734) were associated with influenza A.[/FONT]
  • [FONT=&quot]Among the 323 outbreaks for which the influenza A subtype was available, 59% (192) were associated with influenza A(H3N2);[/FONT]
[FONT=&quot]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

fig6-eng.jpg
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):[/FONT]
  • [FONT=&quot]97.6% (3,018) were associated with influenza A[/FONT]
  • [FONT=&quot]Among the 1,704 cases for which the influenza subtype was available, 1,414 (83%) were associated with A(H1N1)pdm09.[/FONT]
  • [FONT=&quot]The highest estimated rate of hospitalization is among adults over 65 years of age.[/FONT]
[FONT=&quot]Intensive Care Unit (ICU) cases and deaths:[/FONT]
  • [FONT=&quot]To date this season 555 ICU admissions and 182 deaths have been reported.[/FONT]
    • [FONT=&quot]41% (227) of reported ICU admissions were in adults aged 45-64 years.[/FONT]
    • [FONT=&quot]All but eight ICU admissions were associated with influenza A.[/FONT]
    • [FONT=&quot]All but one of the deaths were associated with influenza A.[/FONT]
    [FONT=&quot] [/FONT]
[TABLE="class: table table-striped table-bordered table-hover table-condensed, width: 1140"]
[TR]
[/TR]
[TR]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]0-4[/FONT][/TD]
[TD][FONT=&quot]394[/FONT][/TD]
[TD][FONT=&quot]23[/FONT][/TD]
[TD][FONT=&quot]87.61[/FONT][/TD]
[/TR]
[TR]
[TD][FONT=&quot]5-19[/FONT][/TD]
[TD][FONT=&quot]235[/FONT][/TD]
[TD][FONT=&quot]20[/FONT][/TD]
[TD][FONT=&quot]18.38[/FONT][/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]20-44[/FONT][/TD]
[TD][FONT=&quot]354[/FONT][/TD]
[TD][FONT=&quot]10[/FONT][/TD]
[TD][FONT=&quot]12.79[/FONT][/TD]
[/TR]
[TR]
[TD][FONT=&quot]45-64[/FONT][/TD]
[TD][FONT=&quot]776[/FONT][/TD]
[TD][FONT=&quot]7[/FONT][/TD]
[TD][FONT=&quot]35.98[/FONT][/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]65+[/FONT][/TD]
[TD][FONT=&quot]1259[/FONT][/TD]
[TD][FONT=&quot]14[/FONT][/TD]
[TD][FONT=&quot]104.63[/FONT][/TD]
[/TR]
[TR]
[TD][FONT=&quot]Total[/FONT][/TD]
[TD][FONT=&quot]3018[/FONT][/TD]
[TD][FONT=&quot]74[/FONT][/TD]
[TD] [/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD][FONT=&quot]%[/FONT][/TD]
[TD][FONT=&quot]97.6%[/FONT][/TD]
[TD][FONT=&quot]2.4%[/FONT][/TD]
[TD] [/TD]
[/TR]
[TR]
[TD="colspan: 8"][FONT=&quot]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[/FONT][/TD]
[/TR]
[/TABLE]
[FONT=&quot]Pediatric Influenza Hospitalizations and Deaths

To date this season, 1,280 pediatric hospitalizations have been reported (Figure 7 & 8):[/FONT]
  • [FONT=&quot]66% of cases were in children under 5 years of age.[/FONT]
  • [FONT=&quot]93% (1,192) of cases have been associated with influenza A.[/FONT]
  • [FONT=&quot]Among the 375 cases for which the influenza subtype was available, 305 (81%) were associated with A(H1N1)pdm09.[/FONT]
[FONT=&quot]To date this season, 246 ICU admissions, and 10 deaths have been reported.[/FONT]
  • [FONT=&quot]58% (142) of ICU admissions were in children under 5 years of age.[/FONT]
  • [FONT=&quot]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.[/FONT]
  • [FONT=&quot]80% (8) of deaths occurred in children 2 to 4 years of age.[/FONT]
  • [FONT=&quot]All deaths have been associated with influenza A.[/FONT]
[FONT=&quot]Figure 7 ? Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2019-19

fig7-eng.jpg
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

fig8-eng.jpg
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):[/FONT]
  • [FONT=&quot]873 (93%) hospitalizations were associated with influenza A.[/FONT]
  • [FONT=&quot]A greater proportion of hospitalizations have been reported among adults ≥65 years of age (60%) compared to adults <65 years of age (40%).[/FONT]
  • [FONT=&quot]Among the 204 cases for which the influenza subtype was available, 107 (52%) were associated with A(H1N1)pdm09.[/FONT]
  • [FONT=&quot]86% of hospitalized cases reported more than one type of comorbid condition.[/FONT]
  • [FONT=&quot]The most commonly reported comorbidity was endocrine disorders, which were reported in 87% of hospitalized cases.[/FONT]
[FONT=&quot]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

fig9-eng.jpg
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:[/FONT]
  • [FONT=&quot]20 viruses belonged to genetic group 3C.2a.[/FONT]
  • [FONT=&quot]168 viruses belonged to subclade 3C.2a1.[/FONT]
  • [FONT=&quot]Four viruses belonged to 3C.3a.[/FONT]
  • [FONT=&quot]One isolate could not be sequenced.[/FONT]
[FONT=&quot]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):[/FONT]
  • [FONT=&quot]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.[/FONT]
  • [FONT=&quot]99 viruses showed reduced titer with ferret antisera raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.[/FONT]
  • [FONT=&quot]A/Singapore/INFIMH-16-0019/2016-like virus is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.[/FONT]
  • [FONT=&quot]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.[/FONT]
[FONT=&quot]Influenza A(H1N1):[/FONT]
  • [FONT=&quot]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.[/FONT]
  • [FONT=&quot]43 viruses showed reduced titer with ferret antisera raised against cell culture-propagated A/Michigan/45/2015[/FONT]
[FONT=&quot]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).[/FONT]
  • [FONT=&quot]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.[/FONT]
  • [FONT=&quot]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.[/FONT]
  • [FONT=&quot]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.[/FONT]
  • [FONT=&quot]...[/FONT]
https://www.canada.ca/en/public-hea...watch/2018-2019/week19-may-5-may-11-2019.html
 
[h=1]FluWatch report: May 12 to May 18, 2019 (Week 20)[/h] [FONT=&quot]
pub-eng.jpg

Download the alternative format
(PDF format, 919 KB, 10 pages)
Organization: Public Health Agency of Canada
Date published: 2019-05-24

[h=3]Related Topics[/h]


[h=2]Overall Summary[/h]
  • 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.

[h=2]On this page[/h]



[h=2]Influenza/Influenza-like Illness Activity (geographic spread)[/h] 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.
[h=3]Figure 1 ? Map of overall influenza/ILI activity by province and territory, Canada, week 2019-20[/h]
fig1-eng.jpg
Figure 1 - Text equivalent [h=2]Laboratory-Confirmed Influenza Detections[/h] 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.
[h=3]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[/h]
fig2-eng.jpg
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 [h=3]Figure 3 ? Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2019-20[/h]
fig3-eng.jpg
Figure 3 - Text equivalent [TABLE="class: table table-striped table-bordered table-hover table-condensed, width: 1140"]
Table 1 ? Cumulative numbers of positive influenza specimens by type, subtype and age-group reported through case-based laboratory reporting, Canada, weeks 2018-35 to 2019-20 [TR]
Age groups (years) Cumulative (August 26, 2018 to May 18, 2019) [/TR]
[TR]
Influenza A B Influenza A and B [/TR]
[TR]
A Total A(H1N1) pdm09 A(H3N2) A (UnS)Table 1 ? Note1 Total # % [/TR]
[TR="bgcolor: #F5F5F5"]
[TD]0-4[/TD]
[TD]6739[/TD]
[TD]1691[/TD]
[TD]257[/TD]
[TD]4791[/TD]
[TD]306[/TD]
[TD]7045[/TD]
[TD]18%[/TD]
[/TR]
[TR]
[TD]5-19[/TD]
[TD]5154[/TD]
[TD]1392[/TD]
[TD]484[/TD]
[TD]3278[/TD]
[TD]524[/TD]
[TD]5678[/TD]
[TD]15%[/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD]20-44[/TD]
[TD]6885[/TD]
[TD]2019[/TD]
[TD]613[/TD]
[TD]4253[/TD]
[TD]337[/TD]
[TD]7222[/TD]
[TD]19%[/TD]
[/TR]
[TR]
[TD]45-64[/TD]
[TD]7025[/TD]
[TD]1973[/TD]
[TD]668[/TD]
[TD]4384[/TD]
[TD]123[/TD]
[TD]7148[/TD]
[TD]19%[/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD]65+[/TD]
[TD]10902[/TD]
[TD]1485[/TD]
[TD]2749[/TD]
[TD]6668[/TD]
[TD]254[/TD]
[TD]11156[/TD]
[TD]29%[/TD]
[/TR]
[TR]
[TD]Total[/TD]
[TD]36705[/TD]
[TD]8560[/TD]
[TD]4771[/TD]
[TD]23374[/TD]
[TD]1544[/TD]
[TD]38249[/TD]
[TD]100%[/TD]
[/TR]
[TR]
[TD="colspan: 8"] 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.
[/TD]
[/TR]
[/TABLE]
[h=2]Syndromic / Influenza-like Illness Surveillance[/h] [h=3]Healthcare Professionals Sentinel Syndromic Surveillance[/h] In week 20, 0.8% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4).
[h=3]Figure 4 ? Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2019-20[/h] Number of Sentinels Reporting in Week 20: 74
fig4-eng.jpg
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 [h=2]Participatory Syndromic Surveillance[/h] 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.
[h=3]Figure 5 - Percentage of participants reporting cough and fever, Canada, weeks 2018-40 to 2019-18[/h] Number of Participants Reporting in Week 18: 1,951
fig5-eng.jpg
Figure 5 - Text equivalent [h=2]Influenza Outbreak Surveillance[/h] 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.
[h=3]Figure 6 ? Number of new outbreaks of laboratory-confirmed influenza by report week, Canada, weeks 2018-35 to 2019-20[/h]
fig6-eng.jpg
Figure 6 - Text equivalent [h=2]Severe Outcomes Influenza Surveillance[/h] 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.
[TABLE="class: table table-striped table-bordered table-hover table-condensed, width: 1140"]
Table 2 ? Cumulative number and estimated rate of hospitalizations by age-group reported by participating provinces and territoriesFootnote1, Canada, weeks 2018-35 to 2019-20 [TR]
Age Groups (years) Cumulative (August 26, 2018 to May 18, 2019) [/TR]
[TR]
Influenza A Influenza B Rate per 100,000 population [/TR]
[TR="bgcolor: #F5F5F5"]
[TD]0-4[/TD]
[TD]395[/TD]
[TD]23[/TD]
[TD]87.82[/TD]
[/TR]
[TR]
[TD]5-19[/TD]
[TD]235[/TD]
[TD]20[/TD]
[TD]18.38[/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD]20-44[/TD]
[TD]355[/TD]
[TD]10[/TD]
[TD]12.83[/TD]
[/TR]
[TR]
[TD]45-64[/TD]
[TD]777[/TD]
[TD]7[/TD]
[TD]36.03[/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD]65+[/TD]
[TD]1261[/TD]
[TD]14[/TD]
[TD]104.79[/TD]
[/TR]
[TR]
[TD]Total[/TD]
[TD]3023[/TD]
[TD]74[/TD]
[TD] [/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD]%[/TD]
[TD]97.6%[/TD]
[TD]2.4%[/TD]
[TD] [/TD]
[/TR]
[TR]
[TD="colspan: 8"] 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
[/TD]
[/TR]
[/TABLE]
[h=3]Pediatric Influenza Hospitalizations and Deaths[/h] 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.
[h=3]Figure 7 ? Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2018-35 to 2019-20[/h]
fig7-eng.jpg
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 [h=3]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[/h]
fig8-eng.jpg
Figure 8 - Text equivalent [h=3]Adult Influenza Hospitalizations and Deaths[/h] 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.
[h=3]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[/h]
fig9-eng.jpg
Figure 9 - Text equivalent [h=2]Influenza Strain Characterizations[/h] 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.
[h=3]Genetic Characterization of Influenza A(H3N2):[/h] 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.
[h=3]Antigenic Characterization:[/h] 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.
[h=2]Antiviral Resistance[/h] [h=3]Antiviral Resistance ? Amantadine:[/h] 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.
[h=3]Antiviral Resistance ? Oseltamivir:[/h] 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.
[h=3]Antiviral Resistance ? Zanamivir:[/h] 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.
[h=2]Vaccine Monitoring[/h] Vaccine monitoring refers to activities related to the monitoring of influenza vaccine coverage and effectiveness.
[h=3]Vaccine Coverage[/h] 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).
[TABLE="class: table table-striped table-bordered table-hover table-condensed, width: 1140"]
Table 3 ? Influenza vaccine coverage among adults (≥ 18 years of age) by age group, gender and chronic diseaseTable 3 ? Note1, Seasonal Influenza Vaccination Coverage Survey, Canada, October 2018-February 2019 [TR]
Age group (years) Male Female Combined [/TR]
[TR]
Total Vaccine Coverage (%) Total Vaccine Coverage (%) Total Vaccine Coverage (%) [/TR]
[TR="bgcolor: #F5F5F5"]
[TD="class: text-left"]All adults (≥18)[/TD]
[TD]1568[/TD]
[TD]36.6[/TD]
[TD]2150[/TD]
[TD]46.8[/TD]
[TD]3726[/TD]
[TD]41.8[/TD]
[/TR]
[TR]
[TD="class: text-left"]18-64[/TD]
[TD]1252[/TD]
[TD]28.6[/TD]
[TD]1640[/TD]
[TD]39.9[/TD]
[TD]2898[/TD]
[TD]34.3[/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD="class: text-right"]without chronic diseases[/TD]
[TD]948[/TD]
[TD]25.8[/TD]
[TD]1171[/TD]
[TD]36.1[/TD]
[TD]2124[/TD]
[TD]30.8[/TD]
[/TR]
[TR]
[TD="class: text-right"]with chronic diseases[/TD]
[TD]304[/TD]
[TD]36.3[/TD]
[TD]465[/TD]
[TD]48.5[/TD]
[TD]770[/TD]
[TD]42.8[/TD]
[/TR]
[TR="bgcolor: #F5F5F5"]
[TD="class: text-left"]≥65[/TD]
[TD]316[/TD]
[TD]69.0[/TD]
[TD]510[/TD]
[TD]70.9[/TD]
[TD]828[/TD]
[TD]69.9[/TD]
[/TR]
[TR]
[TD="colspan: 8"] 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.
[/TD]
[/TR]
[/TABLE]
[h=3]Vaccine Effectiveness[/h] 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-hea...atch/2018-2019/week20-may-12-may-18-2019.html

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