FluWatch report: October 16 to October 29, 2022 (weeks 42-43)

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Organization: Public Health Agency of Canada

Published: 2022-11-04

Weekly Highlights

  • At the national level, influenza activity is increasing steeply and has crossed the seasonal threshold of 5% positivity; if percent positivity remains above this threshold next week, the start of an influenza epidemic will be declared.

Virologic

  • In weeks 42 to 43, a total of 1,508 laboratory detections (1,493 influenza A and 26 influenza B) were reported.
  • Influenza A(H3N2) is the dominant subtype, representing 90% of sub-typed influenza A detections this season (August 28, 2022 to October 29, 2022).
  • Among detections with detailed age information to date (August 28, 2022 to October 29, 2022), more than half (54%) were in children and teenagers (ages 0 to 19 years).

Syndromic

  • The percentage of visits for influenza-like illness (ILI) was 1.6% in week 43. The percentage visits for ILI is above the seasonal average.
  • The percentage of FluWatchers reporting fever and cough was 2.3% in week 43. The percentage of FluWatchers reporting cough and fever is above levels typical of this time of year.

Outbreaks

  • From August 28, 2022 to October 29, 2022 (weeks 35 to 43), 17 laboratory-confirmed influenza outbreaks have been reported.

Severe Outcomes

  • From August 28, 2022 to October 29, 2022 (weeks 35 to 43), 72 influenza-associated hospitalizations and 8 ICU admissions have been reported from participating provinces and territories.

Other Notes

  • The next scheduled report (week 44) will be published November 14, 2022.
  • Weekly reporting of laboratory detections of influenza and other seasonal respiratory viruses will continue via our Respiratory Virus Detections Surveillance System.

On this page

Influenza/Influenza-like Illness Activity - Geographic Spread

In week 43, 4 regions in Ontario and New Brunswick reported localized activity and 20 regions in five provinces reported sporadic influenza activity (N.B., Que., Ont., Sask. and Alta.) (Figure 1).

Figure 1 - Map of influenza/ILI activity by province and territory, Canada, week 2022-43

Number of Regions Reporting in Week 43: 40 out of 53

Figure 1. Text version below
Figure 1 - Text description
Province Influenza Surveillance Region Activity Level
N.L. Eastern No Activity
N.L. Labrador-Grenfell No Activity
N.L. Central No Activity
N.L. Western No Activity
P.E.I. Prince Edward Island No Data
N.S. Zone 1 - Western No Data
N.S. Zone 2 - Northern No Data
N.S. Zone 3 - Eastern No Data
N.S. Zone 4 - Central No Data
N.B. Region 1 Sporadic
N.B. Region 2 Localized
N.B. Region 3 Sporadic
N.B. Region 4 No Activity
N.B. Region 5 No Activity
N.B. Region 6 No Activity
N.B. Region 7 No Activity
Que. Nord-est Sporadic
Que. Québec et Chaudieres-Appalaches Sporadic
Que. Centre-du-Québec Sporadic
Que. Montréal et Laval Sporadic
Que. Ouest-du-Québec Sporadic
Que. Montérégie Sporadic
Ont. Central East Localized
Ont. Central West Localized
Ont. Eastern Localized
Ont. North East Sporadic
Ont. North West Sporadic
Ont. South West Sporadic
Ont. Toronto Sporadic
Man. Northern Regional No Activity
Man. Prairie Mountain No Activity
Man. Interlake-Eastern No Activity
Man. Winnipeg No Activity
Man. Southern Health No Activity
Sask. North Sporadic
Sask. Central Sporadic
Sask. South Sporadic
Alta. North Zone Sporadic
Alta. Edmonton Sporadic
Alta. Central Zone Sporadic
Alta. Calgary Sporadic
Alta. South Zone Sporadic
B.C. Interior No Data
B.C. Fraser No Data
B.C. Vancouver Coastal No Data
B.C. Vancouver Island No Data
B.C. Northern No Data
Y.T. Yukon No Activity
N.W.T. North No Activity
N.W.T. South No Activity
Nvt. Qikiqtaaluk No Data
Nvt. Kivalliq No Data
Nvt. Kitimeot No Data

Laboratory-Confirmed Influenza Detections

In week 43, a total of 1,040 laboratory detections (1,034 influenza A and 6 influenza B) were reported. Influenza activity crossed the seasonal threshold of 5% positivity; if percent positivity remains above this threshold next week, the start of an influenza epidemic will be declared at the national level.

The following results were reported from sentinel laboratories across Canada in week 43 (Figures 2 and 3):

To date this season (August 28, 2022 to October 29, 2022):

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 2022-43

Number of Laboratories Reporting in Week 43: 32 out of 34

Figure 2. Text version below
Figure 2 - Text description
Surveillance Week A(Unsubtyped) A(H3N2) A(H1N1) Influenza B Percent Positive A Percent Positive B
35 12 10 2 3 0.2 0.0
36 9 5 1 5 0.1 0.0
37 19 9 3 2 0.2 0.0
38 26 34 20 3 0.5 0.0
39 44 53 22 5 0.7 0.0
40 63 66 16 4 1.0 0.0
41 129 109 20 1 1.5 0.0
42 246 202 11 9 2.7 0.1
43 495 524 15 6 6.4 0.0
Figure 3 - Percentage of tests positive in Canada compared to previous seasons, week 2022-35 to 2022-43
Figure 3. Text version below.

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 description
Surveillance Week Percentage of tests positive, 2022-2023 Percentage of tests positive, 2021-2022 Percentage of tests positive, 2020-2021 Maximum Percentage of Tests Positive Minimum Percentage of Tests Positive Average Percentage of Tests Positive
35 0.2 0.0 0.0 1.9 0.1 0.8
36 0.2 0.0 0.0 2.3 0.3 1.1
37 0.3 0.0 0.0 1.8 0.4 1.0
38 0.5 0.0 0.0 2.4 0.5 1.3
39 0.7 0.0 0.0 2.9 0.7 1.7
40 1.0 0.0 0.0 2.3 1.1 1.7
41 1.5 0.1 0.0 3.0 1.3 1.7
42 2.7 0.1 0.0 3.4 0.9 2.2
43 6.5 0.1 0.0 5.3 0.8 2.8
44 N/A 0.2 0.1 8.5 1.2 3.7
45 N/A 0.1 0.0 10.1 1.4 4.6
46 N/A 0.2 0.0 14.1 1.5 6.1
47 N/A 0.2 0.1 15.4 1.4 7.7
48 N/A 0.3 0.1 18.2 0.8 10.6
49 N/A 0.3 0.0 19.7 1.6 13.0
50 N/A 0.3 0.0 27.0 2.4 16.8
51 N/A 0.2 0.0 29.1 3.3 20.1
52 N/A 0.1 0.0 34.5 4.3 24.5
1 N/A 0.1 0.0 31.7 5.8 23.4
2 N/A 0.1 0.0 29.1 7.1 23.0
3 N/A 0.1 0.0 30.1 12.2 23.6
4 N/A 0.1 0.0 29.5 15.9 24.0
5 N/A 0.0 0.0 30.6 19.6 24.9
6 N/A 0.1 0.0 32.4 17.9 25.0
7 N/A 0.0 0.0 32.5 16.3 25.1
8 N/A 0.1 0.0 32.9 17.5 25.1
9 N/A 0.1 0.0 34.3 16.8 24.6
10 N/A 0.2 0.0 36.0 16.0 23.2
11 N/A 0.3 0.0 31.4 16.2 21.4
12 N/A 0.9 0.0 30.0 15.0 20.1
13 N/A 1.5 0.0 28.3 14.5 19.6
14 N/A 2.5 0.0 23.2 12.7 17.9
15 N/A 3.9 0.0 20.7 11.9 16.3
16 N/A 7.0 0.0 18.5 11.6 14.5
17 N/A 9.7 0.0 17.3 9.8 12.8
18 N/A 11.3 0.0 13.0 7.9 10.3
19 N/A 12.6 0.0 11.9 5.0 9.0
20 N/A 10.4 0.0 9.1 3.2 7.2
21 N/A 9.8 0.0 7.4 3.0 5.6
22 N/A 8.4 0.0 5.0 2.2 3.9
23 N/A 7.0 0.0 4.4 0.9 2.9
24 N/A 5.0 0.0 4.4 0.8 2.2
25 N/A 3.0 0.0 3.9 0.6 1.9
26 N/A 2.3 0.0 3.1 0.7 1.8
27 N/A 1.2 0.0 2.8 0.4 1.5
28 N/A 0.8 0.0 1.8 0.4 0.9
29 N/A 0.7 0.0 1.6 0.5 1.1
30 N/A 0.4 0.0 1.5 0.5 0.9
31 N/A 0.3 0.0 1.9 0.6 1.1
32 N/A 0.2 0.0 1.2 0.5 0.9
33 N/A 0.2 0.0 1.7 0.4 0.9
34 N/A 0.2 0.0 1.6 0.4 0.9

Figure 4 - Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada, week 2022-35 to 2022-43

Figure 4. Text version below.

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 description
a) Proportion of influenza A and B by age-group
Age Group Proportion of Influenza A Proportion of Influenza B Total Number Influenza Detections
0 to 4 97.5% 2.5% 203
5 to 19 99.0% 1.0% 412
20 to 44 96.0% 4.0% 200
45 to 64 100.0% 0.0% 105
65+ 99.1% 0.9% 222
b) Proportion of subtyped influenza A(H1N1) and A(H3N2) by age-group
Age Group Proportion of A(H1N1) Proportion of A(H3N2) Total Number of Subtyped Influenza Detections
0 to 4 7.4% 92.6% 148
5 to 19 7.7% 92.3% 299
20 to 44 9.4% 90.6% 138
45 to 64 15.4% 84.6% 65
65+ 8.6% 91.4% 162

Syndromic / Influenza-like Illness Surveillance

Healthcare Practitioners Sentinel Surveillance

In week 43, 1.6% 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 2022-43

Number of Sentinels Reporting in Week 43: 51

Figure 5. Text version below.

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 description
Surveillance Week 2022-2023 2021-2022 2020-2021 Average Min Max
35 0.6% 0.6% 0.1% 0.6% 0.4% 0.9%
36 0.9% 1.2% 0.2% 0.6% 0.4% 0.9%
37 0.7% 0.6% 0.4% 0.7% 0.5% 1.0%
38 0.8% 0.9% 0.3% 0.7% 0.6% 1.0%
39 1.0% 1.0% 0.4% 0.9% 0.5% 1.2%
40 0.7% 0.5% 0.2% 1.2% 0.8% 1.7%
41 1.9% 1.1% 0.4% 1.7% 0.8% 2.8%
42 1.4% 1.2% 0.5% 1.6% 1.2% 2.1%
43 1.6% 0.9% 0.3% 1.2% 0.8% 1.7%
44 N/A 0.6% 0.3% 1.2% 0.7% 1.7%
45 N/A 1.0% 0.4% 1.2% 0.9% 1.5%
46 N/A 0.9% 0.8% 1.4% 1.2% 1.8%
47 N/A 0.7% 0.3% 1.6% 1.1% 2.2%
48 N/A 1.1% 0.5% 1.5% 1.1% 2.2%
49 N/A 0.9% 0.5% 1.7% 1.0% 2.8%
50 N/A 1.1% 0.4% 1.5% 1.1% 1.7%
51 N/A 1.7% 0.5% 1.9% 1.4% 2.7%
52 N/A 1.5% 0.5% 2.0% 1.0% 3.1%
1 N/A 2.1% 0.7% 3.4% 1.9% 5.4%
2 N/A 1.6% 0.4% 3.4% 1.8% 5.7%
3 N/A 1.4% 0.2% 2.3% 1.3% 3.7%
4 N/A 0.9% 0.3% 2.0% 1.1% 2.9%
5 N/A 1.0% 0.2% 2.1% 1.4% 3.1%
6 N/A 0.7% 0.5% 2.4% 1.4% 4.0%
7 N/A 0.7% 0.3% 2.4% 0.9% 3.5%
8 N/A 0.8% 0.2% 2.3% 0.8% 3.4%
9 N/A 0.7% 0.2% 2.3% 0.9% 3.1%
10 N/A 0.9% 0.2% 2.0% 1.0% 2.8%
11 N/A 0.6% 0.2% 1.9% 1.1% 2.8%
12 N/A 0.8% 0.3% 1.6% 0.6% 2.6%
13 N/A 1.2% 0.4% 1.6% 1.1% 2.6%
14 N/A 1.1% 0.2% 1.7% 1.1% 3.0%
15 N/A 1.2% 0.3% 1.3% 0.9% 1.9%
16 N/A 1.5% 0.3% 1.2% 0.8% 1.7%
17 N/A 1.3% 0.4% 1.2% 0.7% 1.7%
18 N/A 1.8% 0.5% 1.3% 0.5% 2.0%
19 N/A 1.7% 0.3% 0.9% 0.6% 1.3%
20 N/A 1.5% 0.5% 1.1% 0.6% 1.5%
21 N/A 1.4% 0.3% 0.9% 0.5% 1.3%
22 N/A 1.0% 0.3% 0.7% 0.3% 1.0%
23 N/A 1.1% 0.2% 0.8% 0.6% 1.0%
24 N/A 1.3% 0.2% 0.7% 0.6% 1.0%
25 N/A 1.0% 0.2% 0.6% 0.4% 0.8%
26 N/A 0.8% 0.2% 0.8% 0.5% 1.4%
27 N/A 1.7% 0.3% 0.6% 0.5% 0.7%
28 N/A 1.0% 0.1% 0.7% 0.5% 1.3%
29 N/A 0.9% 0.3% 0.9% 0.6% 1.7%
30 N/A 1.3% 0.2% 0.6% 0.2% 0.9%
31 N/A 0.9% 0.2% 0.4% 0.2% 0.6%
32 N/A 0.9% 0.2% 0.8% 0.3% 1.2%
33 N/A 0.8% 0.3% 0.7% 0.4% 1.3%
34 N/A 1.0% 0.5% 0.7% 0.4% 1.5%

FluWatchers

In week 43, 10,701 participants reported to FluWatchers, of which 2.3% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever has slightly increased since week 41 and is above 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 244 participants who reported cough and fever:

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 (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 2022-43

Number of Participants Reporting in Week 43: 10,701

Figure 5. Text version below.

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 description
Surveillance Week 2022-2023 2021-2022 2020-2021 Average Min Max
35 1.3% 0.2% 0.2% N/A N/A N/A
36 1.2% 0.3% 0.2% N/A N/A N/A
37 1.6% 0.5% 0.4% N/A N/A N/A
38 1.8% 0.5% 0.3% N/A N/A N/A
39 2.3% 0.5% 0.4% N/A N/A N/A
40 2.4% 0.6% 0.5% 2.5% 2.2% 2.7%
41 2.0% 0.5% 0.4% 2.2% 1.8% 2.6%
42 2.0% 0.4% 0.3% 1.8% 1.6% 2.0%
43 2.3% 0.5% 0.2% 1.9% 1.5% 2.2%
44 N/A 0.5% 0.3% 1.6% 1.4% 1.8%
45 N/A 0.5% 0.3% 1.8% 1.4% 2.3%
46 N/A 0.4% 0.3% 1.8% 1.2% 2.2%
47 N/A 0.6% 0.3% 1.9% 1.4% 2.4%
48 N/A 0.5% 0.3% 2.4% 1.7% 3.4%
49 N/A 0.4% 0.2% 2.6% 2.0% 3.2%
50 N/A 0.6% 0.1% 2.9% 2.1% 3.8%
51 N/A 1.0% 0.2% 3.2% 2.5% 3.9%
52 N/A 1.5% 0.1% 4.0% 2.8% 5.4%
1 N/A 1.1% 0.1% 3.8% 2.9% 4.8%
2 N/A 1.0% 0.2% 2.9% 1.9% 3.9%
3 N/A 0.8% 0.1% 3.3% 2.3% 4.8%
4 N/A 0.6% 0.1% 3.1% 2.1% 4.2%
5 N/A 0.6% 0.2% 3.2% 2.6% 3.6%
6 N/A 0.5% 0.1% 3.5% 2.8% 4.3%
7 N/A 0.4% 0.2% 3.2% 2.6% 3.8%
8 N/A 0.5% 0.1% 3.1% 2.5% 3.6%
9 N/A 0.5% 0.1% 2.8% 2.4% 3.5%
10 N/A 0.6% 0.2% 2.6% 2.1% 3.1%
11 N/A 0.9% 0.2% 2.3% 1.9% 2.6%
12 N/A 1.2% 0.2% 2.6% 2.5% 2.8%
13 N/A 1.8% 0.2% 2.5% 2.0% 3.1%
14 N/A 2.3% 0.2% 2.1% 1.3% 2.6%
15 N/A 1.9% 0.2% 1.8% 1.6% 1.9%
16 N/A 1.9% 0.1% 2.0% 1.5% 2.4%
17 N/A 1.6% 0.2% 1.7% 1.4% 2.3%
18 N/A 1.4% 0.2% 1.5% 1.2% 2.1%
19 N/A 1.3% 0.1% N/A N/A N/A
20 N/A 1.2% 0.2% N/A N/A N/A
21 N/A 1.2% 0.1% N/A N/A N/A
22 N/A 1.2% 0.1% N/A N/A N/A
23 N/A 1.2% 0.1% N/A N/A N/A
24 N/A 1.3% 0.1% N/A N/A N/A
25 N/A 1.3% 0.1% N/A N/A N/A
26 N/A 1.8% 0.2% N/A N/A N/A
27 N/A 2.0% 0.1% N/A N/A N/A
28 N/A 1.9% 0.2% N/A N/A N/A
29 N/A 1.8% 0.2% N/A N/A N/A
30 N/A 1.6% 0.2% N/A N/A N/A
31 N/A 1.3% 0.2% N/A N/A N/A
32 N/A 1.2% 0.3% N/A N/A N/A
33 N/A 1.4% 0.3% N/A N/A N/A
34 N/A 1.3% 0.5% N/A N/A N/A

Influenza Outbreak Surveillance

In week 43, 5 laboratory-confirmed influenza outbreaks were reported in Canada (2 in long-term care facilities, 1 in a school/daycare, and 2 in facilities categorized as ‘other’). All outbreaks were due to influenza A (unsubtyped).
To date this season (August 28, 2022 to October 29, 2022):

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 territoriesFootnote 1 reporting in week 43: 9 out of 13

Influenza Severe Outcomes Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In week 43, 38 influenza-associated hospitalizations and less than five ICU admissions were reported by participating provinces and territoriesFootnote 2. Less than five influenza-associated deaths were reported.

To date this season (August 28, 2022 to October 29, 2022) among participating provinces and territories:

Number of provinces and territories reporting in week 43: 7 out of 9

Pediatric Influenza Hospitalizations and Deaths

In week 43, 39 influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, well above levels typical of this time of year (Figure 7).

To date this season (August 28, 2022 to October 29, 2022), 53 pediatric influenza-associated hospitalizations and less than 5 ICU admissions have been reported.

Figure 7 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, weeks 2022-35 to 2022-43

Figure 7. Text version below.

Figure 7 - Text description
Surveillance week 2022-2023 2021-2022 Average Min Max
35 0 0 0 0 1
36 1 0 1 0 2
37 0 0 1 0 2
38 1 0 1 0 2
39 1 0 1 0 3
40 1 0 1 0 2
41 4 0 2 0 3
42 6 0 3 0 7
43 39 0 4 1 11
44 #N/A 0 6 1 21
45 #N/A 0 9 2 36
46 #N/A 0 12 1 37
47 #N/A 1 11 1 35
48 #N/A 1 20 2 46
49 #N/A 1 21 3 41
50 #N/A 0 31 4 54
51 #N/A 2 44 5 82
52 #N/A 1 63 14 103
1 #N/A 1 62 21 107
2 #N/A 0 50 12 100
3 #N/A 0 51 27 80
4 #N/A 0 58 34 90
5 #N/A 0 59 25 120
6 #N/A 0 60 15 115
7 #N/A 0 59 17 118
8 #N/A 1 65 25 134
9 #N/A 1 57 12 151
10 #N/A 0 54 17 135
11 #N/A 0 51 16 118
12 #N/A 0 39 13 87
13 #N/A 8 32 15 66
14 #N/A 7 28 12 56
15 #N/A 18 25 11 56
16 #N/A 19 23 11 41
17 #N/A 23 19 9 37
18 #N/A 48 16 8 28
19 #N/A 36 11 5 19
20 #N/A 29 10 0 18
21 #N/A 32 6 4 9
22 #N/A 14 6 1 9
23 #N/A 16 3 1 7
24 #N/A 12 3 1 6
25 #N/A 9 2 0 5
26 #N/A 6 1 0 3
27 #N/A 3 1 0 2
28 #N/A 7 1 0 2
29 #N/A 2 1 0 3
30 #N/A 3 1 0 1
31 #N/A 1 0 0 0
32 #N/A 0 0 0 0
33 #N/A 1 0 0 2
34 #N/A 0 1 0 2

Influenza Strain Characterization

Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 9 influenza viruses (8 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)

Influenza A(H1N1)

Antiviral Resistance

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

Oseltamivir

8 influenza viruses (7 A(H3N2) and 1 A(H1N1)) were tested for resistance to oseltamivir and it was found that:

Zanamivir

8 influenza viruses (7 A(H3N2) and 1 A(H1N1)) were tested for resistance to zanamivir and it was found that:

Influenza Vaccine Monitoring

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

Vaccine Coverage

Influenza vaccine coverage estimates for the 2022-2023 season are anticipated to be available in February or March 2023.

Vaccine Effectiveness

Influenza vaccine effectiveness estimates for the 2022-2023 season are anticipated to be available in February or March 2023.

Provincial and International Surveillance Links

See Influenza surveillance resources

Notes

The data in the FluWatch report represent surveillance data available at the time of writing. All data are preliminary and may change as updates are received.

To learn more about the FluWatch program, see the Overview of influenza monitoring in Canada page.

For more information on the flu, see our Flu (influenza) web page.

We would like to thank all the FluWatch surveillance partners participating in this year's influenza surveillance program.

This report is available on the Government of Canada Influenza webpage.

Ce rapport est disponible dans les deux langues officielles.

Footnote 1

All Provinces and Territories (PTs) participate in the FluWatch outbreak surveillance system. This outbreak system monitors influenza and ILI outbreaks in long-term care facilities(LTCF), acute care facilities, schools and daycares, remote and/or isolated communities, and facilities categorized as ‘other’. Not all reporting PTs report outbreaks in all these settings. All PTs report laboratory confirmed outbreaks in LTCF. Four PTs (NB, NL, NS and YK) report ILI outbreaks in schools and/or daycares and other facilities.

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Footnote 2

Influenza-associated hospitalizations are reported by Alberta, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Prince Edward Island and Yukon. Only hospitalizations that require intensive medical are reported by Saskatchewan.

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