FluWatch report: November 5 to November 11, 2023 (week 45)
Organization: Public Health Agency of Canada
Published: 2023-11-17
Related topics
Weekly highlights
At the national level, influenza activity increased this week but overall activity remains below the seasonal threshold. Sporadic influenza activity continues to be reported in many regions across Canada and the number of regions reporting localized activity is increasing.
Virologic
- In week 45, the percentage of tests positive for influenza was 4.3% and a total of 1,071 laboratory detections (1,038 influenza A and 33 influenza B) were reported.
Syndromic
- The percentage of visits for influenza-like illness (ILI) was 1.3% in week 45. The percentage of visits for ILI is within levels typical of this time of year.
- The percentage of FluWatchers reporting cough and fever was 1.9% in week 45. The percentage of FluWatchers reporting cough and fever is within levels typical of this time of year.
Outbreaks
- From August 27, 2023 to November 11, 2023 (weeks 35 to 45), 32 laboratory-confirmed influenza outbreaks have been reported (7 laboratory-confirmed influenza outbreaks were reported in week 45).
Severe Outcomes
- From August 27, 2023 to November 11, 2023 (weeks 35 to 45), 184 influenza-associated hospitalizations were reported by participating provinces and territories. Adults aged 65 years of age and older accounted for 51% of reported hospitalizations.
Other notes
- Weekly reporting of laboratory detections of influenza, SARS-CoV-2, and other seasonal respiratory viruses will continue via our Respiratory Virus Detections Surveillance System.
- Weekly reporting of SARS-CoV-2 specific trends can be found on the COVID-19 epidemiology update page.
On this page
- Influenza/influenza-like illness activity - Geographic spread
- Laboratory-confirmed influenza detections
- Syndromic / influenza-like illness surveillance
- Influenza outbreak surveillance
- Influenza severe outcomes surveillance
- Influenza strain characterization
- Antiviral resistance
- Influenza vaccine monitoring
- Provincial and international surveillance links
Influenza/influenza-like illness activity - Geographic spread
In week 45, 24 regions across Canada reported sporadic influenza activity and 12 regions in six provinces reported localized influenza activity (N.L., N.S., Ont., Sask., Alta., and B.C.) (Figure 1). The number of regions reporting influenza activity and the intensity of reported activity is increasing. A total of 11 regions in Canada reported no activity this week.
Number of Regions Reporting in week 45: 47 out of 53
Figure 1 - Text description
Province | Influenza Surveillance Region | Activity Level |
---|---|---|
N.L. | Eastern | Localized |
N.L. | Labrador-Grenfell | No Activity |
N.L. | Central | Localized |
N.L. | Western | Sporadic |
P.E.I. | Prince Edward Island | No Data |
N.S. | Zone 1 - Western | Sporadic |
N.S. | Zone 2 - Northern | Localized |
N.S. | Zone 3 - Eastern | Sporadic |
N.S. | Zone 4 - Central | Sporadic |
N.B. | Region 1 | Sporadic |
N.B. | Region 2 | No Activity |
N.B. | Region 3 | No Activity |
N.B. | Region 4 | No Activity |
N.B. | Region 5 | No Activity |
N.B. | Region 6 | No Activity |
N.B. | Region 7 | Sporadic |
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 | Localized |
Ont. | North West | Sporadic |
Ont. | South West | Sporadic |
Ont. | Toronto | Localized |
Man. | Northern Regional | No Data |
Man. | Prairie Mountain | No Data |
Man. | Interlake-Eastern | No Data |
Man. | Winnipeg | No Data |
Man. | Southern Health | No Data |
Sask. | North | Sporadic |
Sask. | Central | Localized |
Sask. | South | Localized |
Alta. | North Zone | Sporadic |
Alta. | Edmonton | Sporadic |
Alta. | Central Zone | Sporadic |
Alta. | Calgary | Localized |
Alta. | South Zone | Sporadic |
B.C. | Interior | Sporadic |
B.C. | Fraser | Sporadic |
B.C. | Vancouver Coastal | Localized |
B.C. | Vancouver Island | Sporadic |
B.C. | Northern | Sporadic |
Y.T. | Yukon | No Activity |
N.W.T. | North | No Activity |
N.W.T. | South | Sporadic |
Nvt. | Qikiqtaaluk | No Activity |
Nvt. | Kivalliq | No Activity |
Nvt. | Kitimeot | No Activity |
Laboratory-confirmed influenza detections
The weekly percentage of tests positive for influenza (4.3% in week 45) continues to increase but is within expected levels for this time of year. Influenza activity remains below the seasonal threshold.
The following results were reported from sentinel laboratories across Canada in week 45 (Figures 2 and 3):
- A total of 1,071 laboratory detections (1,038 influenza A and 33 influenza B) were reported.
- Among subtyped influenza A detections (366), 89% (327) were influenza A(H1N1).
- Among detections for which age information was reported (985), 353 (36%) of detections were in individuals aged 0-19 years old. Across adult age groups, similar proportions are being observed: 24%: 20-44 years old, 19%: 45-64 years old , and 21%: 65+ years old.
To date this season (August 27, 2023 to November 11, 2023):
- 3,065 influenza detections were reported, of which 95% (2,897) were influenza A and among subtyped influenza A detections (1,270), influenza A(H1N1) accounted for 84% of detections.
- 2,580 laboratory-confirmed influenza detections with age information were reported, of which 830 (32%) were in individuals aged 0-19 years old and 697 (27%) were in individuals aged 65+ 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.
Number of Laboratories Reporting in week 45: 34 out of 35
Figure 2 - Text description
Surveillance Week | A(Unsubtyped) | A(H3N2) | A(H1N1) | Influenza B | Percent Positive A | Percent Positive B |
---|---|---|---|---|---|---|
35 | 19 | 26 | 51 | 9 | 0.7 | 0.1 |
36 | 12 | 11 | 50 | 9 | 0.4 | 0.1 |
37 | 28 | 14 | 46 | 6 | 0.5 | 0.0 |
38 | 28 | 15 | 57 | 4 | 0.5 | 0.0 |
39 | 18 | 10 | 75 | 20 | 0.5 | 0.1 |
40 | 41 | 20 | 79 | 13 | 0.7 | 0.1 |
41 | 43 | 11 | 53 | 7 | 0.5 | 0.0 |
42 | 60 | 15 | 95 | 19 | 0.7 | 0.1 |
43 | 109 | 28 | 129 | 23 | 1.2 | 0.1 |
44 | 305 | 54 | 308 | 25 | 2.7 | 0.1 |
45 | 606 | 39 | 327 | 33 | 4.2 | 0.1 |
46 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
47 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
48 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
49 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
50 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
51 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
52 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
1 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
2 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
3 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
4 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
5 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
6 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
7 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
8 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
9 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
10 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
11 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
12 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
13 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
14 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
15 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
16 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
17 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
18 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
19 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
20 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
21 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
22 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
23 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
24 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
25 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
26 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
27 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
28 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
29 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
30 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
31 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
32 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
33 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
34 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
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, 2023-2024 | Percentage of tests positive, 2022-2023 | Percentage of tests positive, 2021-2022 | Maximum Percentage of Tests Positive | Minimum Percentage of Tests Positive | Average Percentage of Tests Positive |
---|---|---|---|---|---|---|
35 | 0.8 | 0.2 | 0.0 | 1.9 | 0.1 | 0.8 |
36 | 0.5 | 0.2 | 0.0 | 2.3 | 0.3 | 1.1 |
37 | 0.5 | 0.3 | 0.0 | 1.8 | 0.4 | 1.0 |
38 | 0.5 | 0.5 | 0.0 | 2.4 | 0.6 | 1.3 |
39 | 0.6 | 0.7 | 0.0 | 3.0 | 0.6 | 1.7 |
40 | 0.7 | 1.0 | 0.0 | 2.3 | 1.1 | 1.7 |
41 | 0.5 | 1.4 | 0.1 | 3.0 | 1.3 | 1.7 |
42 | 0.8 | 2.4 | 0.1 | 3.4 | 0.9 | 2.2 |
43 | 1.3 | 5.5 | 0.1 | 5.3 | 0.8 | 2.8 |
44 | 2.8 | 10.8 | 0.2 | 8.4 | 1.2 | 3.7 |
45 | 4.3 | 16.2 | 0.1 | 10.1 | 1.4 | 4.6 |
46 | - | 20.3 | 0.2 | 14.1 | 1.5 | 6.0 |
47 | - | 24.3 | 0.2 | 15.4 | 1.4 | 7.7 |
48 | - | 24.1 | 0.3 | 18.2 | 0.8 | 10.6 |
49 | - | 21.2 | 0.3 | 19.3 | 1.6 | 12.9 |
50 | - | 17.4 | 0.3 | 27.0 | 2.4 | 16.4 |
51 | - | 12.5 | 0.2 | 29.1 | 3.3 | 20.0 |
52 | - | 8.0 | 0.1 | 34.5 | 4.3 | 24.4 |
1 | - | 4.6 | 0.1 | 31.7 | 5.9 | 23.5 |
2 | - | 2.3 | 0.1 | 29.1 | 7.1 | 23.0 |
3 | - | 1.5 | 0.1 | 30.1 | 12.2 | 23.7 |
4 | - | 1.1 | 0.1 | 29.5 | 15.9 | 24.0 |
5 | - | 1.0 | 0.0 | 30.6 | 19.6 | 24.9 |
6 | - | 1.0 | 0.0 | 32.4 | 17.9 | 25.0 |
7 | - | 0.9 | 0.0 | 32.5 | 16.3 | 25.1 |
8 | - | 1.1 | 0.1 | 32.9 | 17.6 | 25.2 |
9 | - | 1.3 | 0.1 | 34.3 | 16.8 | 24.4 |
10 | - | 1.4 | 0.2 | 36.0 | 16.1 | 23.3 |
11 | - | 1.7 | 0.3 | 31.4 | 16.2 | 21.4 |
12 | - | 1.9 | 0.9 | 30.0 | 15.0 | 20.1 |
13 | - | 2.4 | 1.5 | 28.3 | 14.5 | 19.6 |
14 | - | 2.2 | 2.5 | 26.2 | 12.7 | 19.1 |
15 | - | 2.5 | 3.9 | 20.7 | 12.0 | 16.3 |
16 | - | 2.4 | 7.0 | 18.5 | 11.6 | 14.5 |
17 | - | 2.4 | 9.7 | 17.3 | 9.8 | 12.8 |
18 | - | 2.3 | 11.3 | 13.0 | 7.9 | 10.3 |
19 | - | 2.1 | 12.6 | 12.0 | 5.0 | 9.0 |
20 | - | 2.1 | 10.4 | 9.1 | 3.2 | 7.2 |
21 | - | 1.6 | 9.8 | 7.5 | 3.0 | 5.6 |
22 | - | 1.6 | 8.4 | 4.9 | 2.2 | 3.9 |
23 | - | 1.3 | 7.0 | 4.4 | 0.9 | 2.9 |
24 | - | 1.1 | 5.0 | 4.4 | 0.8 | 2.3 |
25 | - | 1.0 | 3.0 | 4.0 | 0.6 | 1.9 |
26 | - | 0.7 | 2.3 | 3.0 | 0.7 | 1.8 |
27 | - | 0.6 | 1.2 | 2.8 | 0.4 | 1.4 |
28 | - | 0.8 | 0.8 | 1.8 | 0.4 | 0.9 |
29 | - | 0.5 | 0.7 | 1.5 | 0.5 | 1.1 |
30 | - | 0.5 | 0.4 | 1.5 | 0.5 | 0.9 |
31 | - | 0.5 | 0.3 | 1.9 | 0.6 | 1.1 |
32 | - | 0.7 | 0.2 | 1.2 | 0.5 | 0.9 |
33 | - | 0.7 | 0.2 | 1.7 | 0.4 | 0.9 |
34 | - | 0.6 | 0.2 | 1.6 | 0.4 | 0.9 |
Laboratory data notes:
Testing for influenza and other respiratory viruses has been influenced by the 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
Age Group | Proportion of Influenza A | Proportion of Influenza A | Total Number Influenza Detections |
---|---|---|---|
0 to 4 | 95.0% | 5.0% | 358 |
5 to 19 | 91.5% | 8.5% | 472 |
20 to 44 | 92.6% | 7.4% | 530 |
45 to 64 | 98.1% | 1.9% | 523 |
65+ | 97.4% | 2.6% | 697 |
Age Group | Proportion of Influenza A | Proportion of Influenza A | Total Number Influenza Detections |
---|---|---|---|
0 to 4 | 87.7% | 12.3% | 146 |
5 to 19 | 92.4% | 7.6% | 211 |
20 to 44 | 80.7% | 19.3% | 233 |
45 to 64 | 90.4% | 9.6% | 219 |
65+ | 79.3% | 20.7% | 319 |
Syndromic / influenza-like illness surveillance
Healthcare practitioners sentinel surveillance
In week 45, 1.3% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 5). The percentage of visits for ILI has increased but is within 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 a smaller number of sentinels reporting compared to previous seasons.
Number of Sentinels Reporting in week 45: 36
The shaded area represents the maximum and minimum percentage of visits for ILI 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.
Figure 5 - Text description
Surveillance Week | 2023-2024 | 2022-2023 | 2021-2022 | Average | Min | Max |
---|---|---|---|---|---|---|
35 | 0.5% | 0.6% | 0.1% | 0.6% | 0.4% | 0.9% |
36 | 0.4% | 1.2% | 0.2% | 0.6% | 0.4% | 0.9% |
37 | 0.8% | 0.6% | 0.4% | 0.7% | 0.5% | 1.0% |
38 | 0.8% | 0.9% | 0.3% | 0.7% | 0.6% | 1.0% |
39 | 0.9% | 1.0% | 0.4% | 0.9% | 0.5% | 1.2% |
40 | 0.6% | 0.5% | 0.2% | 1.2% | 0.8% | 1.7% |
41 | 1.6% | 1.1% | 0.4% | 1.7% | 0.8% | 2.8% |
42 | 1.0% | 1.2% | 0.5% | 1.6% | 1.2% | 2.1% |
43 | 0.8% | 0.9% | 0.3% | 1.2% | 0.8% | 1.7% |
44 | 1.3% | 0.6% | 0.3% | 1.2% | 0.7% | 1.7% |
45 | 1.3% | 1.0% | 0.4% | 1.2% | 0.9% | 1.5% |
46 | - | 0.9% | 0.8% | 1.4% | 1.2% | 1.8% |
47 | - | 0.7% | 0.3% | 1.6% | 1.1% | 2.2% |
48 | - | 1.1% | 0.5% | 1.5% | 1.1% | 2.2% |
49 | - | 0.9% | 0.5% | 1.7% | 1.0% | 2.8% |
50 | - | 1.1% | 0.4% | 1.5% | 1.1% | 1.7% |
51 | - | 1.7% | 0.5% | 1.9% | 1.4% | 2.7% |
52 | - | 1.5% | 0.5% | 2.0% | 1.0% | 3.1% |
1 | - | 2.1% | 0.7% | 3.4% | 1.9% | 5.4% |
2 | - | 1.6% | 0.4% | 3.4% | 1.8% | 5.7% |
3 | - | 1.4% | 0.2% | 2.3% | 1.3% | 3.7% |
4 | - | 0.9% | 0.3% | 2.0% | 1.1% | 2.9% |
5 | - | 1.0% | 0.2% | 2.1% | 1.4% | 3.1% |
6 | - | 0.7% | 0.5% | 2.4% | 1.4% | 4.0% |
7 | - | 0.7% | 0.3% | 2.4% | 0.9% | 3.5% |
8 | - | 0.8% | 0.2% | 2.3% | 0.8% | 3.4% |
9 | - | 0.7% | 0.2% | 2.3% | 0.9% | 3.1% |
10 | - | 0.9% | 0.2% | 2.0% | 1.0% | 2.8% |
11 | - | 0.6% | 0.2% | 1.9% | 1.1% | 2.8% |
12 | - | 0.8% | 0.3% | 1.6% | 0.6% | 2.6% |
13 | - | 1.2% | 0.4% | 1.6% | 1.1% | 2.6% |
14 | - | 1.1% | 0.2% | 1.7% | 1.1% | 3.0% |
15 | - | 1.2% | 0.3% | 1.3% | 0.9% | 1.9% |
16 | - | 1.5% | 0.3% | 1.2% | 0.8% | 1.7% |
17 | - | 1.3% | 0.4% | 1.2% | 0.7% | 1.7% |
18 | - | 1.8% | 0.5% | 1.3% | 0.5% | 2.0% |
19 | - | 1.7% | 0.3% | 0.9% | 0.6% | 1.3% |
20 | - | 1.5% | 0.5% | 1.1% | 0.6% | 1.5% |
21 | - | 1.4% | 0.3% | 0.9% | 0.5% | 1.3% |
22 | - | 1.0% | 0.3% | 0.7% | 0.3% | 1.0% |
23 | - | 1.1% | 0.2% | 0.8% | 0.6% | 1.0% |
24 | - | 1.3% | 0.2% | 0.7% | 0.6% | 1.0% |
25 | - | 1.0% | 0.2% | 0.6% | 0.4% | 0.8% |
26 | - | 0.8% | 0.2% | 0.8% | 0.5% | 1.4% |
27 | - | 1.7% | 0.3% | 0.6% | 0.5% | 0.7% |
28 | - | 1.0% | 0.1% | 0.7% | 0.5% | 1.3% |
29 | - | 0.9% | 0.3% | 0.9% | 0.6% | 1.7% |
30 | - | 1.3% | 0.2% | 0.6% | 0.2% | 0.9% |
31 | - | 0.9% | 0.2% | 0.4% | 0.2% | 0.6% |
32 | - | 0.9% | 0.2% | 0.8% | 0.3% | 1.2% |
33 | - | 0.8% | 0.3% | 0.7% | 0.4% | 1.3% |
34 | - | 1.0% | 0.5% | 0.7% | 0.4% | 1.5% |
FluWatchers
In week 45, 9,210 participants reported to FluWatchers, of which 1.9% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers reporting cough and fever has increased but is within expected levels for 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. 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 174 participants who reported cough and fever:
- 21% consulted a healthcare professional.
- 79% reported days missed from work or school, resulting in an average of 2.9 missed days from work or school among those 137 participants.
The Northwest Territories had the highest participation rate this week (54 participants per 100,000 population) and the neighbourhood with postal code, K0A had the highest number of participants (122). 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.
Number of Participants Reporting in week 45: 9,210
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 | 2023-2024 | 2022-2023 | 2021-2022 | Average | Min | Max |
---|---|---|---|---|---|---|
35 | 1.1% | 1.3% | 0.2% | - | - | - |
36 | 1.2% | 1.2% | 0.3% | - | - | - |
37 | 1.5% | 1.6% | 0.5% | - | - | - |
38 | 2.0% | 1.8% | 0.5% | - | - | - |
39 | 2.3% | 2.3% | 0.5% | - | - | - |
40 | 1.8% | 2.4% | 0.6% | 2.5% | 2.2% | 2.7% |
41 | 1.6% | 2.0% | 0.5% | 2.2% | 1.8% | 2.6% |
42 | 1.7% | 2.0% | 0.4% | 1.8% | 1.6% | 2.0% |
43 | 1.7% | 2.3% | 0.5% | 1.9% | 1.5% | 2.2% |
44 | 1.9% | 2.6% | 0.5% | 1.6% | 1.4% | 1.8% |
45 | 1.9% | 3.0% | 0.5% | 1.8% | 1.4% | 2.3% |
46 | - | 2.9% | 0.4% | 1.8% | 1.2% | 2.2% |
47 | - | 3.1% | 0.6% | 1.9% | 1.4% | 2.4% |
48 | - | 3.1% | 0.5% | 2.4% | 1.7% | 3.4% |
49 | - | 2.7% | 0.4% | 2.6% | 2.0% | 3.2% |
50 | - | 2.1% | 0.6% | 2.9% | 2.1% | 3.8% |
51 | - | 2.4% | 1.0% | 3.2% | 2.5% | 3.9% |
52 | - | 2.1% | 1.5% | 4.0% | 2.8% | 5.4% |
1 | - | 1.7% | 1.1% | 3.8% | 2.9% | 4.8% |
2 | - | 1.3% | 1.0% | 2.9% | 1.9% | 3.9% |
3 | - | 1.3% | 0.8% | 3.3% | 2.3% | 4.8% |
4 | - | 1.2% | 0.6% | 3.1% | 2.1% | 4.2% |
5 | - | 1.1% | 0.6% | 3.2% | 2.6% | 3.6% |
6 | - | 1.4% | 0.5% | 3.5% | 2.8% | 4.3% |
7 | - | 1.3% | 0.4% | 3.2% | 2.6% | 3.8% |
8 | - | 1.3% | 0.5% | 3.1% | 2.5% | 3.6% |
9 | - | 1.4% | 0.5% | 2.8% | 2.4% | 3.5% |
10 | - | 1.5% | 0.6% | 2.6% | 2.1% | 3.1% |
11 | - | 1.5% | 0.9% | 2.3% | 1.9% | 2.6% |
12 | - | 1.3% | 1.2% | 2.6% | 2.5% | 2.8% |
13 | - | 1.5% | 1.8% | 2.5% | 2.0% | 3.1% |
14 | - | 1.3% | 2.3% | 2.1% | 1.3% | 2.6% |
15 | - | 1.4% | 1.9% | 1.8% | 1.6% | 1.9% |
16 | - | 1.2% | 1.9% | 2.0% | 1.5% | 2.4% |
17 | - | 1.2% | 1.6% | 1.7% | 1.4% | 2.3% |
18 | - | 1.1% | 1.4% | 1.5% | 1.2% | 2.1% |
19 | - | 0.9% | 1.3% | - | - | - |
20 | - | 1.0% | 1.2% | - | - | - |
21 | - | 0.9% | 1.2% | - | - | - |
22 | - | 0.7% | 1.2% | - | - | - |
23 | - | 0.9% | 1.2% | - | - | - |
24 | - | 0.9% | 1.3% | - | - | - |
25 | - | 0.7% | 1.3% | - | - | - |
26 | - | 0.9% | 1.8% | - | - | - |
27 | - | 0.8% | 2.0% | - | - | - |
28 | - | 0.6% | 1.9% | - | - | - |
29 | - | 0.6% | 1.8% | - | - | - |
30 | - | 0.7% | 1.6% | - | - | - |
31 | - | 1.0% | 1.3% | - | - | - |
32 | - | 0.9% | 1.2% | - | - | - |
33 | - | 0.9% | 1.4% | - | - | - |
34 | - | 1.2% | 1.3% | - | - | - |
Influenza outbreak surveillance
In week 45, seven laboratory-confirmed influenza outbreaks were reported.
To date this season (August 27, 2023 to November 11, 2023):
- 32 laboratory-confirmed influenza outbreaks have been reported
- 21 were in LTC facilities (66%)
- 8 were in a facility categorized as ‘other’ (25%)
- 3 were in acute care facilities (9%)
- All outbreaks were due to influenza A and among those with subtyping information (15), 80% were due to influenza A(H1N1)
- 8 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.
Number of provinces and territoriesFootnote 1 reporting in week 45: 11 out of 13
Figure 7 - Text description
Surveillance Week | Acute Care Facilities | Long Term Care Facilities | Other | Schools and Daycares | Remote and/or Isolated Communities |
---|---|---|---|---|---|
35 | 0 | 1 | 1 | 0 | 0 |
36 | 0 | 0 | 0 | 0 | 0 |
37 | 0 | 2 | 0 | 0 | 0 |
38 | 0 | 2 | 0 | 0 | 0 |
39 | 0 | 1 | 0 | 0 | 0 |
40 | 0 | 2 | 0 | 0 | 0 |
41 | 0 | 1 | 0 | 0 | 0 |
42 | 0 | 2 | 0 | 0 | 0 |
43 | 0 | 2 | 1 | 0 | 0 |
44 | 2 | 6 | 2 | 0 | 0 |
45 | 1 | 2 | 4 | 0 | 0 |
46 | 0 | 0 | 0 | 0 | 0 |
47 | 0 | 0 | 0 | 0 | 0 |
48 | 0 | 0 | 0 | 0 | 0 |
49 | 0 | 0 | 0 | 0 | 0 |
50 | 0 | 0 | 0 | 0 | 0 |
51 | 0 | 0 | 0 | 0 | 0 |
52 | 0 | 0 | 0 | 0 | 0 |
1 | 0 | 0 | 0 | 0 | 0 |
2 | 0 | 0 | 0 | 0 | 0 |
3 | 0 | 0 | 0 | 0 | 0 |
4 | 0 | 0 | 0 | 0 | 0 |
5 | 0 | 0 | 0 | 0 | 0 |
6 | 0 | 0 | 0 | 0 | 0 |
7 | 0 | 0 | 0 | 0 | 0 |
8 | 0 | 0 | 0 | 0 | 0 |
9 | 0 | 0 | 0 | 0 | 0 |
10 | 0 | 0 | 0 | 0 | 0 |
11 | 0 | 0 | 0 | 0 | 0 |
12 | 0 | 0 | 0 | 0 | 0 |
13 | 0 | 0 | 0 | 0 | 0 |
14 | 0 | 0 | 0 | 0 | 0 |
15 | 0 | 0 | 0 | 0 | 0 |
16 | 0 | 0 | 0 | 0 | 0 |
17 | 0 | 0 | 0 | 0 | 0 |
18 | 0 | 0 | 0 | 0 | 0 |
19 | 0 | 0 | 0 | 0 | 0 |
20 | 0 | 0 | 0 | 0 | 0 |
21 | 0 | 0 | 0 | 0 | 0 |
22 | 0 | 0 | 0 | 0 | 0 |
23 | 0 | 0 | 0 | 0 | 0 |
24 | 0 | 0 | 0 | 0 | 0 |
25 | 0 | 0 | 0 | 0 | 0 |
26 | 0 | 0 | 0 | 0 | 0 |
27 | 0 | 0 | 0 | 0 | 0 |
28 | 0 | 0 | 0 | 0 | 0 |
29 | 0 | 0 | 0 | 0 | 0 |
30 | 0 | 0 | 0 | 0 | 0 |
31 | 0 | 0 | 0 | 0 | 0 |
32 | 0 | 0 | 0 | 0 | 0 |
33 | 0 | 0 | 0 | 0 | 0 |
34 | 0 | 0 | 0 | 0 | 0 |
Influenza severe outcomes surveillance
Provincial/territorial influenza hospitalizations and deaths
In week 45, 42 influenza-associated hospitalizations, 8 ICU admissions, and less than 5 influenza-associated deaths were reported by participating provinces and territoriesFootnote 2.
To date this season (August 27, 2023 to November 11, 2023), 184 influenza-associated hospitalizations were reported by participating provinces and territories:
- 97% of the hospitalizations were associated with influenza A.
- Of the cases with subtype information (149), 85% were associated with influenza A(H1N1)
- Adults aged 65 years of age and older accounted for 51% of reported hospitalizations.
To date this season (August 27, 2023 to November 11, 2023), 21 ICU admissions and 6 influenza-associated deaths were reported.
Number of provinces and territories reporting in week 45: 7 out of 9
Pediatric influenza hospitalizations and deaths
Data for laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were not available for weeks 45.
Influenza strain characterization
Since September 1, 2023, the National Microbiology Laboratory Branch (NMLB) has characterized 79 influenza viruses (63 A(H1N1), 9 A(H3N2), and 7 influenza B) received from Canadian laboratories.
Antigenic Characterization
Changes in circulating influenza viruses are monitored by antigenic characterization. Antigenic characterization results show how similar the circulating viruses are to reference viruses. Reference viruses represent strains included in the current seasonal influenza vaccine.
Influenza A(H1N1)
A/Wisconsin/67/2022 is the influenza A(H1N1) component of the 2023-2024 Northern Hemisphere influenza vaccine.
- 63 H1N1 viruses were characterized as antigenically similar to A/Wisconsin/67/2022-like with antisera produced against cell-grown A/Wisconsin/67/2022.
Influenza A(H3N2)
A/Darwin/6/2021 (H3N2)-like virus is the influenza A(H3N2) component of the 2023-2024 Northern Hemisphere influenza vaccine.
- 8 influenza A(H3N2) were antigenically similar to A/Darwin/6/2021 (H3N2)-like virus using antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus.
- 1 influenza A(H3N2) showed reduced titer with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus.
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 2023-2024 Northern Hemisphere influenza vaccine are B/Austria/1359417/2021 (Victoria lineage) and B/Phuket/3073/2013 (Yamagata lineage)
- 7 viruses characterized were antigenically similar to B/Austria/1359417/2021.
Genetic Characterization
Genetic characterization is used to determine how similar gene sequences of circulating influenza viruses are to the sequences of the vaccine components used in the current seasonal influenza vaccine.
Since September 1, 2023, NMLB has genetically characterized 70 influenza viruses.
Virus Subtype or Lineage | HA Clade | Number of Viruses Characterized | HA Subclade | Number of viruses Characterized | HA genetic clades and subclades of the 2023-2024 Northern Hemisphere influenza vaccine components |
---|---|---|---|---|---|
A(H1N1) | 6B.1A.5a | 57 | 2a | 14 | The A(H1N1) component belongs to genetic clade 6B.1A.5a.2a.1 |
2a.1 | 43 | ||||
A(H3N2) | 3C.2a1b.2a | 9 | 2a.3a.1 | 9 | The A(H3N2) component belongs to genetic clade 3C.2a1b.2a.2a |
B/Victoria | V1A | 4 | 3a.2 | 4 | The B/Victoria component belongs to genetic clade V1A.3 |
B/Yamagata | Y3 | 0 | Y3 | 0 | The B/Yamagata component belongs to genetic clade Y3 |
Antiviral resistance
The National Microbiology Laboratory Branch also tests influenza viruses received from Canadian laboratories for antiviral resistance.
Oseltamivir
70 influenza viruses (9 H3N2, 57 H1N1 and 4 influenza B) were tested for resistance to oseltamivir.
- All influenza viruses were sensitive to oseltamivir.
Zanamivir
70 influenza viruses (9 H3N2, 57 H1N1 and 4 influenza B) were tested for resistance to zanamivir.
- All influenza viruses were sensitive to zanamivir.
Influenza vaccine monitoring
Vaccine monitoring refers to activities related to the monitoring of influenza vaccination coverage and vaccine effectiveness.
Vaccination coverage
Influenza vaccine coverage estimates for the 2023-2024 season are anticipated to be available in February or March 2024.
Vaccine effectiveness
Influenza vaccine effectiveness estimates for the 2023-2024 season are anticipated to be available in February or March 2024.
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. Six PTs (AB, SK, NB, NS, PEI, and NL) report ILI outbreaks in schools and/or daycares and other facilities.
- 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 care are reported by Saskatchewan.
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