FluWatch report: November 28 to December 4, 2021 (week 48)
Organization: Public Health Agency of Canada
Published: 2021-12-10
Related Topics
Weekly Highlights
- In week 48, influenza activity across Canada was low with 20% of regions reporting any influenza activity. In the past week, all influenza indicators remain at low interseasonal levels.
Virologic
- In week 48, a total of 61 influenza detections (33 influenza A and 28 influenza B) were reported.
- Among the 47 detections with detailed age information, 89% were in individuals under the age of 65 years.
Syndromic
- The percentage visits for influenza-like illness (ILI) was 1.2% in week 48 and is within expected levels.
- The percentage of FluWatchers reporting fever and cough was 0.52% in week 48; it remains below expected levels and is stable.
Outbreaks
- In week 48, one ILI outbreak was reported.
- From August 29 to December 4, 2021 (weeks 35 to 48), 14 ILI outbreaks and no laboratory-confirmed influenza outbreaks have been reported.
Severe Outcomes
- From August 29 to December 4, 2021 (weeks 35 to 48), less than five influenza-associated hospitalizations have been reported from participating provinces and territories.
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 Influenza Reports
Influenza/Influenza-like Illness Activity - Geographic Spread
In week 48, nine regions in five provinces (Alta., Ont., Que., N.B., and N.S.) reported sporadic influenza/ILI activity. All other surveillance regions reported no influenza/ILI activity (Figure 1).
Number of Regions Reporting in Week 48: 44 out of 53
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 Activity |
N.S. | Zone 2 - Northern | No Activity |
N.S. | Zone 3 - Eastern | No Activity |
N.S. | Zone 4 - Central | Sporadic |
N.B. | Region 1 | No Activity |
N.B. | Region 2 | No Activity |
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 | No Activity |
Que. | Centre-du-Québec | Sporadic |
Que. | Montréal et Laval | No Activity |
Que. | Ouest-du-Québec | No Activity |
Que. | Montérégie | No Activity |
Ont. | Central East | Sporadic |
Ont. | Central West | Sporadic |
Ont. | Eastern | No Activity |
Ont. | North East | No Activity |
Ont. | North West | No Activity |
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 | No Data |
Sask. | Central | No Data |
Sask. | South | No Data |
Alta. | North Zone | No Activity |
Alta. | Edmonton | Sporadic |
Alta. | Central Zone | No Activity |
Alta. | Calgary | No Activity |
Alta. | South Zone | No Activity |
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 Activity |
Nvt. | Kivalliq | No Activity |
Nvt. | Kitimeot | No Activity |
Laboratory-Confirmed Influenza Detections
In week 48, 61 laboratory detections of influenza were reported (33 influenza A and 28 influenza B).
Overall, the percentage of laboratory tests positive for influenza remains at exceptionally low levels, despite the elevated levels of testing. In week 48, 17,785 tests for influenza were performed at reporting laboratories and the percentage of tests positive for influenza was 0.34%. Compared to the past six pre-pandemic seasons (2014-2015 to 2019-2020), an average of 5,645 tests were performed for this time period, with an average of 10.6% of tests positive for influenza (Figure 3).
To date this season (August 28 to December 4, 2021), 212 influenza detections (127 influenza A and 85 influenza B) have been reported, which is lower than what we have seen historically in the past six pre-pandemic seasons, where an average of 2,170 influenza detections were reported at this point in the season. Among subtyped influenza A detections (43), influenza A(H3N2) accounted for 96% of detections.
Detailed information on age and type/subtype has been received for 175 laboratory-confirmed influenza detections (Figure 4). Among the 175 detections, 149 (85%) were in individuals under the age of 45.
Included in the cumulative detections this season are 11 co-infections of influenza A and B (total of 22 detections) that are suspected to be associated with recent live attenuated influenza vaccine (LAIV) receipt. Co-infections known or reported to be associated with recent LAIV have been removed by the submitting laboratory or by the Public Health Agency of Canada beginning in week 44 as they do not represent community transmission of seasonal influenza viruses.
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 weeks or previous seasons.
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 48: 32 out of 34
For one province, only data from subtyped influenza A specimens are included in the weekly number of positive influenza tests in Figure 2. The number of positive tests reported in Figure 2 may not equal the total number of positive tests in the report body text.
Figure 2 - Text description
Surveillance Week | A(Unsubtyped) | A(H3N2) | A(H1N1) | Influenza B | Percent Positive A | Percent Positive B |
---|---|---|---|---|---|---|
35 | 3 | 0 | 0 | 0 | 0.0 | 0.0 |
36 | 1 | 0 | 0 | 0 | 0.0 | 0.0 |
37 | 1 | 3 | 0 | 0 | 0.0 | 0.0 |
38 | 0 | 0 | 0 | 0 | 0.0 | 0.0 |
39 | 0 | 0 | 1 | 0 | 0.0 | 0.0 |
40 | 0 | 0 | 0 | 2 | 0.0 | 0.0 |
41 | 2 | 1 | 0 | 3 | 0.0 | 0.0 |
42 | 0 | 1 | 1 | 2 | 0.0 | 0.0 |
43 | 2 | 1 | 0 | 3 | 0.0 | 0.0 |
44 | 1 | 2 | 0 | 16 | 0.1 | 0.1 |
45 | 2 | 9 | 0 | 10 | 0.1 | 0.1 |
46 | 3 | 8 | 0 | 9 | 0.1 | 0.1 |
47 | 4 | 11 | 0 | 12 | 0.2 | 0.1 |
48 | 8 | 7 | 0 | 28 | 0.2 | 0.2 |
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.
Figure 3 - Text description
Surveillance Week | Number of Tests, 2021-2022 | Number of Tests, 2020-2021 | Maximum Number of Tests | Minimum Number of Tests | Average Number of Tests |
---|---|---|---|---|---|
35 | 7140 | 4996 | 1979 | 1311 | 1705 |
36 | 8012 | 5192 | 2208 | 1323 | 1707 |
37 | 9317 | 5335 | 2631 | 1778 | 2135 |
38 | 9821 | 6024 | 3039 | 1987 | 2502 |
39 | 9691 | 6707 | 3356 | 2365 | 2859 |
40 | 10776 | 7127 | 4078 | 2443 | 3134 |
41 | 10369 | 6817 | 4339 | 2673 | 3240 |
42 | 12506 | 6755 | 4649 | 2648 | 3526 |
43 | 13339 | 8227 | 4996 | 3084 | 3862 |
44 | 15441 | 9615 | 4966 | 2994 | 4020 |
45 | 17547 | 10748 | 5912 | 3117 | 4508 |
46 | 16413 | 11955 | 5589 | 3176 | 4564 |
47 | 16651 | 13103 | 6541 | 3587 | 5018 |
48 | 17785 | 18762 | 7416 | 3569 | 5645 |
49 | N/A | 19649 | 8559 | 3836 | 6377 |
50 | N/A | 16189 | 9464 | 4017 | 7155 |
51 | N/A | 14059 | 11142 | 3487 | 8822 |
52 | N/A | 12290 | 11338 | 4272 | 9184 |
1 | N/A | 11681 | 14932 | 5371 | 12552 |
2 | N/A | 14097 | 16104 | 5315 | 13289 |
3 | N/A | 17002 | 15001 | 5270 | 11820 |
4 | N/A | 15391 | 15414 | 5873 | 11441 |
5 | N/A | 16607 | 16595 | 6739 | 11456 |
6 | N/A | 12949 | 16121 | 8324 | 11339 |
7 | N/A | 20727 | 14443 | 8074 | 10842 |
8 | N/A | 21290 | 14024 | 7606 | 10865 |
9 | N/A | 21891 | 14520 | 7507 | 10956 |
10 | N/A | 20896 | 17681 | 7005 | 11084 |
11 | N/A | 21220 | 12714 | 6435 | 9175 |
12 | N/A | 23087 | 10431 | 5976 | 8238 |
13 | N/A | 25811 | 9989 | 6063 | 7699 |
14 | N/A | 26303 | 8830 | 4773 | 7046 |
15 | N/A | 26284 | 7836 | 5090 | 6527 |
16 | N/A | 26792 | 6826 | 5000 | 5890 |
17 | N/A | 29154 | 6603 | 4440 | 5305 |
18 | N/A | 22152 | 5640 | 4143 | 4780 |
19 | N/A | 12725 | 5480 | 3680 | 4311 |
20 | N/A | 9738 | 5097 | 3046 | 3862 |
21 | N/A | 7442 | 4001 | 2577 | 3197 |
22 | N/A | 6765 | 3790 | 2424 | 2944 |
23 | N/A | 6341 | 3257 | 1969 | 2591 |
24 | N/A | 5942 | 3120 | 2034 | 2449 |
25 | N/A | 5774 | 2659 | 1731 | 2148 |
26 | N/A | 5972 | 2600 | 1573 | 1988 |
27 | N/A | 5213 | 2163 | 1554 | 1833 |
28 | N/A | 4900 | 2223 | 1451 | 1857 |
29 | N/A | 5122 | 2256 | 1436 | 1796 |
30 | N/A | 5275 | 1950 | 1463 | 1664 |
31 | N/A | 5398 | 2022 | 1386 | 1671 |
32 | N/A | 4692 | 1928 | 1269 | 1574 |
33 | N/A | 5616 | 2089 | 1251 | 1671 |
34 | N/A | 5851 | 2098 | 1374 | 1698 |
Surveillance Week | 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 | 0.04 | 0.02 | 1.87 | 0.11 | 0.82 |
36 | 0.01 | 0.00 | 2.28 | 0.30 | 1.13 |
37 | 0.04 | 0.00 | 1.78 | 0.40 | 0.99 |
38 | 0.00 | 0.02 | 2.35 | 0.55 | 1.30 |
39 | 0.01 | 0.00 | 2.95 | 0.67 | 1.71 |
40 | 0.02 | 0.00 | 2.33 | 1.08 | 1.70 |
41 | 0.06 | 0.01 | 3.02 | 1.32 | 1.72 |
42 | 0.05 | 0.00 | 3.40 | 0.87 | 2.18 |
43 | 0.05 | 0.01 | 5.32 | 0.84 | 2.83 |
44 | 0.21 | 0.07 | 8.55 | 1.20 | 3.70 |
45 | 0.14 | 0.04 | 10.10 | 1.39 | 4.63 |
46 | 0.16 | 0.03 | 14.11 | 1.51 | 6.05 |
47 | 0.23 | 0.07 | 15.36 | 1.44 | 7.71 |
48 | 0.34 | 0.05 | 18.20 | 0.84 | 10.61 |
49 | N/A | 0.04 | 19.71 | 1.64 | 13.01 |
50 | N/A | 0.01 | 27.02 | 2.36 | 16.82 |
51 | N/A | 0.01 | 29.09 | 3.30 | 20.11 |
52 | N/A | 0.00 | 34.54 | 4.28 | 24.48 |
1 | N/A | 0.00 | 31.66 | 5.85 | 23.41 |
2 | N/A | 0.00 | 29.10 | 7.06 | 23.01 |
3 | N/A | 0.01 | 30.07 | 12.24 | 23.63 |
4 | N/A | 0.00 | 29.45 | 15.89 | 23.96 |
5 | N/A | 0.00 | 30.62 | 19.60 | 24.90 |
6 | N/A | 0.02 | 32.39 | 17.89 | 25.00 |
7 | N/A | 0.01 | 32.51 | 16.28 | 25.05 |
8 | N/A | 0.00 | 32.87 | 17.45 | 25.14 |
9 | N/A | 0.00 | 34.28 | 16.80 | 24.59 |
10 | N/A | 0.00 | 35.99 | 16.05 | 23.22 |
11 | N/A | 0.01 | 31.41 | 16.19 | 21.41 |
12 | N/A | 0.00 | 30.03 | 15.03 | 20.10 |
13 | N/A | 0.00 | 28.25 | 14.50 | 19.56 |
14 | N/A | 0.00 | 23.16 | 12.66 | 17.86 |
15 | N/A | 0.01 | 20.73 | 11.95 | 16.27 |
16 | N/A | 0.00 | 18.52 | 11.64 | 14.48 |
17 | N/A | 0.00 | 17.30 | 9.76 | 12.83 |
18 | N/A | 0.00 | 13.02 | 7.88 | 10.26 |
19 | N/A | 0.00 | 11.95 | 4.96 | 8.98 |
20 | N/A | 0.01 | 9.13 | 3.19 | 7.22 |
21 | N/A | 0.01 | 7.45 | 2.97 | 5.60 |
22 | N/A | 0.00 | 4.96 | 2.19 | 3.86 |
23 | N/A | 0.00 | 4.39 | 0.87 | 2.86 |
24 | N/A | 0.02 | 4.36 | 0.81 | 2.25 |
25 | N/A | 0.00 | 3.95 | 0.63 | 1.88 |
26 | N/A | 0.00 | 3.08 | 0.69 | 1.81 |
27 | N/A | 0.00 | 2.83 | 0.42 | 1.48 |
28 | N/A | 0.00 | 1.84 | 0.41 | 0.91 |
29 | N/A | 0.00 | 1.55 | 0.47 | 1.09 |
30 | N/A | 0.04 | 1.46 | 0.46 | 0.90 |
31 | N/A | 0.00 | 1.93 | 0.58 | 1.11 |
32 | N/A | 0.00 | 1.19 | 0.52 | 0.92 |
33 | N/A | 0.00 | 1.69 | 0.40 | 0.85 |
34 | N/A | 0.02 | 1.57 | 0.42 | 0.92 |
Figure 4 - Text description
Age Group | Proportion of Influenza A | Proportion of Influenza B | Total Number Influenza Detections |
---|---|---|---|
0 to 4 | 57.6% | 42.4% | 59 |
5 to 19 | 60.0% | 40.0% | 35 |
20 to 44 | 61.8% | 38.2% | 55 |
45 to 64 | 47.1% | 52.9% | 17 |
65+ | 55.6% | 44.4% | 9 |
Age Group | Proportion of A(H1N1) | Proportion of A(H3N2) | Total Number of Subtyped Influenza Detections |
---|---|---|---|
0 to 4 | 22.2% | 77.8% | 9 |
5 to 19 | 0.0% | 100.0% | 8 |
20 to 44 | 0.0% | 100.0% | 13 |
45 to 64 | 0.0% | 100.0% | 4 |
65+ | 0.0% | 100.0% | 1 |
Syndromic / Influenza-like Illness Surveillance
Healthcare Practitioners Sentinel Surveillance
In week 48, 1.2% of visits to healthcare professionals were due to influenza-like illness (ILI). Since the beginning of the surveillance season, the percentage of visits for ILI has been within or near expected pre-pandemic levels (Figure 5).
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.
Number of Sentinels Reporting in Week 48: 46
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 | 2021-2022 | 2020-2021 | Average | Min | Max |
---|---|---|---|---|---|
35 | 0.6% | 0.1% | 0.6% | 0.4% | 0.9% |
36 | 1.2% | 0.2% | 0.6% | 0.4% | 0.9% |
37 | 0.6% | 0.4% | 0.7% | 0.5% | 1.0% |
38 | 0.9% | 0.3% | 0.7% | 0.6% | 1.0% |
39 | 1.0% | 0.4% | 0.9% | 0.5% | 1.2% |
40 | 0.5% | 0.2% | 1.2% | 0.8% | 1.7% |
41 | 1.1% | 0.4% | 1.7% | 0.8% | 2.8% |
42 | 1.2% | 0.5% | 1.6% | 1.2% | 2.1% |
43 | 0.9% | 0.3% | 1.2% | 0.8% | 1.7% |
44 | 0.6% | 0.3% | 1.2% | 0.7% | 1.7% |
45 | 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 | 1.2% | 0.5% | 1.5% | 1.1% | 2.2% |
49 | N/A | 0.5% | 1.7% | 1.0% | 2.8% |
50 | N/A | 0.4% | 1.5% | 1.1% | 1.7% |
51 | N/A | 0.5% | 1.9% | 1.4% | 2.7% |
52 | N/A | 0.5% | 2.0% | 1.0% | 3.1% |
1 | N/A | 0.7% | 3.4% | 1.9% | 5.4% |
2 | N/A | 0.4% | 3.4% | 1.8% | 5.7% |
3 | N/A | 0.2% | 2.3% | 1.3% | 3.7% |
4 | N/A | 0.3% | 2.0% | 1.1% | 2.9% |
5 | N/A | 0.2% | 2.1% | 1.4% | 3.1% |
6 | N/A | 0.5% | 2.4% | 1.4% | 4.0% |
7 | N/A | 0.3% | 2.4% | 0.9% | 3.5% |
8 | N/A | 0.2% | 2.3% | 0.8% | 3.4% |
9 | N/A | 0.2% | 2.3% | 0.9% | 3.1% |
10 | N/A | 0.2% | 2.0% | 1.0% | 2.8% |
11 | N/A | 0.2% | 1.9% | 1.1% | 2.8% |
12 | N/A | 0.3% | 1.6% | 0.6% | 2.6% |
13 | N/A | 0.4% | 1.6% | 1.1% | 2.6% |
14 | N/A | 0.2% | 1.7% | 1.1% | 3.0% |
15 | N/A | 0.3% | 1.3% | 0.9% | 1.9% |
16 | N/A | 0.3% | 1.2% | 0.8% | 1.7% |
17 | N/A | 0.4% | 1.2% | 0.7% | 1.7% |
18 | N/A | 0.5% | 1.3% | 0.5% | 2.0% |
19 | N/A | 0.3% | 0.9% | 0.6% | 1.3% |
20 | N/A | 0.5% | 1.1% | 0.6% | 1.5% |
21 | N/A | 0.3% | 0.9% | 0.5% | 1.3% |
22 | N/A | 0.3% | 0.7% | 0.3% | 1.0% |
23 | N/A | 0.2% | 0.8% | 0.6% | 1.0% |
24 | N/A | 0.2% | 0.7% | 0.6% | 1.0% |
25 | N/A | 0.2% | 0.6% | 0.4% | 0.8% |
26 | N/A | 0.2% | 0.8% | 0.5% | 1.4% |
27 | N/A | 0.3% | 0.6% | 0.5% | 0.7% |
28 | N/A | 0.1% | 0.7% | 0.5% | 1.3% |
29 | N/A | 0.3% | 0.9% | 0.6% | 1.7% |
30 | N/A | 0.2% | 0.6% | 0.2% | 0.9% |
31 | N/A | 0.2% | 0.4% | 0.2% | 0.6% |
32 | N/A | 0.2% | 0.8% | 0.3% | 1.2% |
33 | N/A | 0.3% | 0.7% | 0.4% | 1.3% |
34 | N/A | 0.5% | 0.7% | 0.4% | 1.5% |
FluWatchers
In week 48, 12,807 participants reported to FluWatchers, of which 0.52% reported symptoms of cough and fever (Figure 6). 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.
The percentage of participants reporting cough and fever has been stable this season, and remains at lower than expected levels. This may be a direct effect of individual and public health measures taken to reduce the spread of COVID-19. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.
Among the 67 participants who reported cough and fever:
- 64% consulted a healthcare professional;
- 81% reported days missed from work or school, resulting in a combined total of 154 missed days of work or school (average of 2.3 days).
Manitoba had the highest participation rate this week (47 participants per 100,000 population) and the neighbourhood of K0A had the highest number of participants (151). 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 48: 12,807
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 | 2021-2022 | 2020-2021 | Average | Min | Max |
---|---|---|---|---|---|
35 | 0.23% | 0.22% | N/A | N/A | N/A |
36 | 0.28% | 0.21% | N/A | N/A | N/A |
37 | 0.49% | 0.38% | N/A | N/A | N/A |
38 | 0.54% | 0.29% | N/A | N/A | N/A |
39 | 0.54% | 0.45% | N/A | N/A | N/A |
40 | 0.58% | 0.49% | 2.51% | 2.18% | 2.71% |
41 | 0.46% | 0.44% | 2.18% | 1.81% | 2.57% |
42 | 0.38% | 0.33% | 1.80% | 1.61% | 2.03% |
43 | 0.53% | 0.17% | 1.87% | 1.49% | 2.18% |
44 | 0.51% | 0.26% | 1.57% | 1.39% | 1.78% |
45 | 0.54% | 0.29% | 1.83% | 1.42% | 2.32% |
46 | 0.41% | 0.28% | 1.83% | 1.22% | 2.15% |
47 | 0.57% | 0.31% | 1.93% | 1.44% | 2.39% |
48 | 0.52% | 0.26% | 2.43% | 1.67% | 3.35% |
49 | 0.00% | 0.17% | 2.56% | 1.97% | 3.16% |
50 | 0.00% | 0.15% | 2.91% | 2.12% | 3.79% |
51 | 0.00% | 0.22% | 3.18% | 2.53% | 3.95% |
52 | 0.00% | 0.10% | 3.98% | 2.81% | 5.38% |
1 | 0.00% | 0.12% | 3.84% | 2.85% | 4.76% |
2 | 0.00% | 0.21% | 2.94% | 1.90% | 3.93% |
3 | 0.00% | 0.12% | 3.25% | 2.35% | 4.84% |
4 | 0.00% | 0.12% | 3.12% | 2.13% | 4.23% |
5 | 0.00% | 0.17% | 3.19% | 2.62% | 3.59% |
6 | 0.00% | 0.11% | 3.47% | 2.76% | 4.28% |
7 | 0.00% | 0.16% | 3.18% | 2.58% | 3.79% |
8 | 0.00% | 0.06% | 3.09% | 2.54% | 3.65% |
9 | 0.00% | 0.10% | 2.81% | 2.38% | 3.53% |
10 | 0.00% | 0.18% | 2.58% | 2.12% | 3.11% |
11 | 0.00% | 0.16% | 2.33% | 1.89% | 2.63% |
12 | 0.00% | 0.17% | 2.60% | 2.46% | 2.82% |
13 | 0.00% | 0.17% | 2.48% | 1.99% | 3.06% |
14 | 0.00% | 0.19% | 2.13% | 1.35% | 2.58% |
15 | 0.00% | 0.21% | 1.78% | 1.60% | 1.93% |
16 | 0.00% | 0.14% | 2.00% | 1.47% | 2.44% |
17 | 0.00% | 0.22% | 1.73% | 1.40% | 2.31% |
18 | 0.00% | 0.15% | 1.50% | 1.19% | 2.09% |
19 | 0.00% | 0.14% | N/A | N/A | N/A |
20 | 0.00% | 0.15% | N/A | N/A | N/A |
21 | 0.00% | 0.09% | N/A | N/A | N/A |
22 | 0.00% | 0.10% | N/A | N/A | N/A |
23 | 0.00% | 0.08% | N/A | N/A | N/A |
24 | 0.00% | 0.13% | N/A | N/A | N/A |
25 | 0.00% | 0.12% | N/A | N/A | N/A |
26 | 0.00% | 0.16% | N/A | N/A | N/A |
27 | 0.00% | 0.11% | N/A | N/A | N/A |
28 | 0.00% | 0.20% | N/A | N/A | N/A |
29 | 0.00% | 0.20% | N/A | N/A | N/A |
30 | 0.00% | 0.22% | N/A | N/A | N/A |
31 | 0.00% | 0.21% | N/A | N/A | N/A |
32 | 0.00% | 0.25% | N/A | N/A | N/A |
33 | 0.00% | 0.31% | N/A | N/A | N/A |
34 | 0.00% | 0.50% | N/A | N/A | N/A |
Influenza Outbreak Surveillance
In week 48, one ILI outbreak in a school/daycare was reported.
To date this season (August 28 to December 4, 2021), 14 ILI outbreaks and no laboratory-confirmed influenza outbreaks have been reported. The most recent laboratory-confirmed influenza outbreak occurred in week 24 (week ending June 13, 2020) of the 2019-2020 season.
All ILI outbreaks have been reported in schools and/or daycares. The number of ILI outbreaks reported to date this season is lower than the 2020-2021 season but higher than in pre-pandemic seasons. This is not unexpected given changes to outbreak surveillance, specifically increased vigilance in schools to monitor and report absenteeism due to ILI, and the increased restrictions on attendance for children with symptoms of viral respiratory illness.
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. For more information on the respiratory viruses currently circulating in Canada, please refer to the Respiratory Virus Detections in Canada.
Number of provinces and territoriesFootnote 1 reporting in week 48: 11 out of 13
Influenza Severe Outcomes Surveillance
Provincial/Territorial Influenza Hospitalizations and Deaths
In week 48, less than five influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote 2.
To date this season (August 28 to December 4, 2021), less than five influenza-associated hospitalizations were reported by participating provinces and territories.
Number of provinces and territories reporting in week 48: 8 out of 9
Pediatric Influenza Hospitalizations and Deaths
In week 48, less than five pediatric (≤16 years of age) influenza-associated hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network.
To date this season (August 28 to December 4, 2021), less than five pediatric influenza-associated hospitalizations and less than five intensive care unit (ICU) admissions were reported by the IMPACT network.
Adult Influenza Hospitalizations and Deaths
In week 48, no influenza-associated adult (≥16 years of age) hospitalizations were reported by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network.
To date this season (August 28 to December 4), less than five influenza-associated adult (≥16 years of age) hospitalizations have been reported by the CIRN SOS network, with the most recent influenza-associated hospitalization reported in week 46 (week ending November 20, 2021).
Influenza Strain Characterization
To date this season (August 28 to December 4), the National Microbiology Laboratory (NML) has characterized two influenza viruses (2 influenza A(H1N1)) received from Canadian laboratories.
- One H1N1 virus characterized was antigenically similar to A/Wisconsin/588/2019.
- One H1N1 showed reduced titer with ferret antisera raised against cell culture-propagated A/Wisconsin/588/2019
A/Wisconsin/588/2019 is the influenza A(H1N1) component of the 2021-2022 Northern Hemisphere seasonal influenza vaccine.
Antiviral Resistance
The NML also tests influenza viruses received from Canadian laboratories for antiviral resistance.
Oseltamivir
Two influenza viruses (2 H1N1) were tested for resistance to oseltamivir:
- All influenza viruses were sensitive to oseltamivir.
Zanamivir
Two influenza viruses (2 H1N1) was 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 vaccine coverage and effectiveness.
Vaccine Coverage
Influenza vaccine coverage estimates for the 2021-2022 season are anticipated to be available in February or March 2022.
Vaccine Effectiveness
Influenza vaccine effectiveness estimates for the 2021-2022 season are anticipated to be available in February or March 2022, pending the resumption of community transmission of seasonal influenza.
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.
- 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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