FluWatch report: March 6, 2022 to March 12, 2022 (week 10)

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Organization: Public Health Agency of Canada

Published: 2022-03-18

Weekly Highlights

  • Influenza activity across Canada remains low for this time of year. Low numbers of sporadic detections of influenza continue to be reported. There has been no evidence of community circulation of influenza in the 2021-2022 season to date.

Virologic

  • In week 10, a total of 17 influenza detections (17 influenza A and 0 influenza B) were reported.
  • Detections of influenza have increased in recent weeks; however, the overall number of weekly detections remain low.

Syndromic

  • The percentage visits for influenza-like illness (ILI) was 1.0 % in week 10; a slow increasing trend in recent weeks.
  • The percentage of FluWatchers reporting fever and cough was 0.7% in week 10; a slow increasing trend in recent weeks.
    • FluWatchers is fueled by Canadians. Become a FluWatcher today and help us track flu-like illnesses in your community!

Outbreaks

  • In week 10, no outbreaks were reported.
  • From August 29, 2021 to March 12, 2022 (weeks 35 to 10), 18 ILI outbreaks and no laboratory-confirmed influenza outbreaks have been reported.

Severe Outcomes

  • From August 29, 2021 to March 12, 2022 (weeks 35 to 10), less than five influenza-associated hospitalizations have been reported from participating provinces and territories.

Other Notes

  • The next FluWatch report (weeks 11-14) will be published April 22, 2022.
  • Weekly reporting of laboratory detections of influenza and other seasonal respiratory viruses will continue via our Respiratory Virus Detections Surveillance System. Reports are published on Thursdays.

On this page

Influenza/Influenza-like Illness Activity - Geographic Spread

In week 10, twelve regions in five provinces (B.C., Alta., Sask., Ont., Que.) reported sporadic influenza/ILI activity. All other surveillance regions reported no influenza/ILI activity (Figure 1).

Figure 1 - Map of influenza/ILI activity by province and territory, Canada, week 2022-10

Number of Regions Reporting in Week 10: 52 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 Activity
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 No Activity
N.B. Region 1 No Activity
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 No Activity
Que. Nord-est No Activity
Que. Québec et Chaudieres-Appalaches No Activity
Que. Centre-du-Québec No Activity
Que. Montréal et Laval Sporadic
Que. Ouest-du-Québec No Activity
Que. Montérégie Sporadic
Ont. Central East Sporadic
Ont. Central West No Activity
Ont. Eastern Sporadic
Ont. North East No Activity
Ont. North West No Activity
Ont. South West No Activity
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 No Activity
Sask. South No Activity
Alta. North Zone Sporadic
Alta. Edmonton Sporadic
Alta. Central Zone No Activity
Alta. Calgary Sporadic
Alta. South Zone Sporadic
B.C. Interior No Activity
B.C. Fraser Sporadic
B.C. Vancouver Coastal Sporadic
B.C. Vancouver Island No Activity
B.C. Northern No Activity
Y.T. Yukon No Data
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 10, seventeen laboratory detections (all influenza A) were reported.

Overall, the percentage of laboratory tests positive for influenza remains at exceptionally low levels, despite continued testing at levels similar to previous seasons. In week 10, 10,612 tests for influenza were performed at reporting laboratories and the percentage of tests positive for influenza was 0.13%. Compared to the past six pre-pandemic seasons (2014-2015 to 2019-2020), an average of 11,084 tests were performed for this time period, with an average of 23% of tests positive for influenza (Figure 3).

To date this season (August 29, 2021 to March 12, 2022), 551 influenza detections (435 influenza A and 116 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 38,193 influenza detections were reported at this point in the season. Among subtyped influenza A detections (126), influenza A(H3N2) accounted for 91% of detections.

Detailed information on age and type/subtype has been received for 434 laboratory-confirmed influenza detections (Figure 4). Among the 434 detections, 351 (81%) were in individuals under the age of 45.

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.

Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, week 2022-10

Number of Laboratories Reporting in Week 10: 32 out of 34

Figure 2. Text version below

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 11 7 0 28 0.2 0.2
49 29 6 0 9 0.2 0.1
50 19 12 1 4 0.3 0.0
51 25 12 1 6 0.2 0.0
52 10 12 1 2 0.1 0.0
1 10 11 1 1 0.1 0.0
2 16 2 2 3 0.1 0.0
3 4 2 0 2 0.0 0.0
4 4 2 0 0 0.1 0.0
5 4 0 0 1 0.0 0.0
6 2 1 0 1 0.0 0.0
7 1 1 0 0 0.0 0.0
8 6 1 1 2 0.1 0.0
9 10 5 2 0 0.2 0.0
10 8 5 0 0 0.2 0.0
Figure 3 - Number of influenza tests and percentage of tests positive in Canada compared to previous seasons, week 2022-10
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.

Included in the cumulative detections this season are 11 co-infections of influenza A and B (total of 22 detections) that were suspected to be associated with live attenuated influenza vaccine (LAIV) receipt. Beginning in week 44 co-infections known or reported to be associated with recent LAIV were removed by the submitting laboratory or by the Public Health Agency of Canada as they do not represent community transmission of seasonal influenza viruses.

Figure 3 - Text description
a) Number of influenza tests, 2020-2021 compared to previous seasons
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 10372 6817 4339 2673 3240
42 12508 6755 4649 2648 3526
43 13341 8227 4996 3084 3862
44 15442 9615 4966 2994 4020
45 17547 10748 5912 3117 4508
46 16418 11955 5589 3176 4564
47 16923 13103 6541 3587 5018
48 18532 18762 7416 3569 5645
49 19974 19649 8559 3836 6377
50 22549 16189 9464 4017 7155
51 28471 14059 11142 3487 8822
52 29557 12290 11338 4272 9184
1 28420 11681 14932 5371 12552
2 23659 14097 16104 5315 13289
3 19585 17002 15001 5270 11820
4 16496 15391 15414 5873 11441
5 15977 16607 16595 6739 11456
6 13873 12949 16121 8324 11339
7 13127 20727 14443 8074 10842
8 12181 21290 14024 7606 10865
9 11284 21891 14520 7507 10956
10 10612 20896 17681 7005 11084
11 - 21220 12714 6435 9175
12 - 23087 10431 5976 8238
13 - 25811 9989 6063 7699
14 - 26303 8830 4773 7046
15 - 26284 7836 5090 6527
16 - 26792 6826 5000 5890
17 - 29154 6603 4440 5305
18 - 22152 5640 4143 4780
19 - 12725 5480 3680 4311
20 - 9738 5097 3046 3862
21 - 7442 4001 2577 3197
22 - 6765 3790 2424 2944
23 - 6341 3257 1969 2591
24 - 5942 3120 2034 2449
25 - 5774 2659 1731 2148
26 - 5972 2600 1573 1988
27 - 5213 2163 1554 1833
28 - 4900 2223 1451 1857
29 - 5122 2256 1436 1796
30 - 5275 1950 1463 1664
31 - 5398 2022 1386 1671
32 - 4692 1928 1269 1574
33 - 5616 2089 1251 1671
34 - 5851 2098 1374 1698
b) Percentage of tests positive for influenza, 2020-2021 compared to previous seasons
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 0.35 0.05 18.20 0.84 10.61
49 0.28 0.04 19.71 1.64 13.01
50 0.27 0.01 27.02 2.36 16.82
51 0.20 0.01 29.09 3.30 20.11
52 0.10 0.00 34.54 4.28 24.48
1 0.10 0.00 31.66 5.85 23.41
2 0.12 0.00 29.10 7.06 23.01
3 0.05 0.01 30.07 12.24 23.63
4 0.05 0.00 29.45 15.89 23.96
5 0.04 0.00 30.62 19.60 24.90
6 0.04 0.02 32.39 17.89 25.00
7 0.02 0.01 32.51 16.28 25.05
8 0.08 0.00 32.87 17.45 25.14
9 0.15 0.00 34.28 16.80 24.59
10 0.16 0.00 35.99 16.05 23.22
11 - 0.01 31.41 16.19 21.41
12 - 0.00 30.03 15.03 20.10
13 - 0.00 28.25 14.50 19.56
14 - 0.00 23.16 12.66 17.86
15 - 0.01 20.73 11.95 16.27
16 - 0.00 18.52 11.64 14.48
17 - 0.00 17.30 9.76 12.83
18 - 0.00 13.02 7.88 10.26
19 - 0.00 11.95 4.96 8.98
20 - 0.01 9.13 3.19 7.22
21 - 0.01 7.45 2.97 5.60
22 - 0.00 4.96 2.19 3.86
23 - 0.00 4.39 0.87 2.86
24 - 0.02 4.36 0.81 2.25
25 - 0.00 3.95 0.63 1.88
26 - 0.00 3.08 0.69 1.81
27 - 0.00 2.83 0.42 1.48
28 - 0.00 1.84 0.41 0.91
29 - 0.00 1.55 0.47 1.09
30 - 0.04 1.46 0.46 0.90
31 - 0.00 1.93 0.58 1.11
32 - 0.00 1.19 0.52 0.92
33 - 0.00 1.69 0.40 0.85
34 - 0.02 1.57 0.42 0.92
Figure 4 - Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada, weeks 2021-35 to 2022-10

Figure 4. Text version below.

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 74.4% 25.6% 121
5 to 19 82.1% 17.9% 84
20 to 44 80.8% 19.2% 146
45 to 64 77.3% 22.7% 44
65+ 74.4% 25.6% 39
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 29.4% 70.6% 17
5 to 19 6.7% 93.3% 15
20 to 44 2.8% 97.2% 36
45 to 64 0.0% 100.0% 10
65+ 9.1% 90.9% 11

Syndromic / Influenza-like Illness Surveillance

Healthcare Practitioners Sentinel Surveillance

In week 10, 1% 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). 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 2021-35 to 2022-10

Number of Sentinels Reporting in Week 10: 45

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 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 1.1% 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 0.9% 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 1.0% 0.2% 2.0% 1.0% 2.8%
11 - 0.2% 1.9% 1.1% 2.8%
12 - 0.3% 1.6% 0.6% 2.6%
13 - 0.4% 1.6% 1.1% 2.6%
14 - 0.2% 1.7% 1.1% 3.0%
15 - 0.3% 1.3% 0.9% 1.9%
16 - 0.3% 1.2% 0.8% 1.7%
17 - 0.4% 1.2% 0.7% 1.7%
18 - 0.5% 1.3% 0.5% 2.0%
19 - 0.3% 0.9% 0.6% 1.3%
20 - 0.5% 1.1% 0.6% 1.5%
21 - 0.3% 0.9% 0.5% 1.3%
22 - 0.3% 0.7% 0.3% 1.0%
23 - 0.2% 0.8% 0.6% 1.0%
24 - 0.2% 0.7% 0.6% 1.0%
25 - 0.2% 0.6% 0.4% 0.8%
26 - 0.2% 0.8% 0.5% 1.4%
27 - 0.3% 0.6% 0.5% 0.7%
28 - 0.1% 0.7% 0.5% 1.3%
29 - 0.3% 0.9% 0.6% 1.7%
30 - 0.2% 0.6% 0.2% 0.9%
31 - 0.2% 0.4% 0.2% 0.6%
32 - 0.2% 0.8% 0.3% 1.2%
33 - 0.3% 0.7% 0.4% 1.3%
34 - 0.5% 0.7% 0.4% 1.5%

FluWatchers

In week 10, 11,678 participants reported to FluWatchers, of which 0.65% 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. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

Among the 77 participants who reported cough and fever:

The Northwest Territories had the highest participation rate this week (55 participants per 100,000 population) and the neighbourhood of K2J had the highest number of participants (146). 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 2022-10

Number of Participants Reporting in Week 10: 11,678

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 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 0.51% 0.26% 2.43% 1.67% 3.35%
49 0.40% 0.17% 2.56% 1.97% 3.16%
50 0.60% 0.15% 2.91% 2.12% 3.79%
51 1.03% 0.22% 3.18% 2.53% 3.95%
52 1.51% 0.10% 3.98% 2.81% 5.38%
1 1.08% 0.12% 3.84% 2.85% 4.76%
2 0.99% 0.21% 2.94% 1.90% 3.93%
3 0.77% 0.12% 3.25% 2.35% 4.84%
4 0.56% 0.12% 3.12% 2.13% 4.23%
5 0.64% 0.17% 3.19% 2.62% 3.59%
6 0.51% 0.11% 3.47% 2.76% 4.28%
7 0.43% 0.16% 3.18% 2.58% 3.79%
8 0.49% 0.06% 3.09% 2.54% 3.65%
9 0.45% 0.10% 2.81% 2.38% 3.53%
10 0.66% 0.18% 2.58% 2.12% 3.11%
11 - 0.16% 2.33% 1.89% 2.63%
12 - 0.17% 2.60% 2.46% 2.82%
13 - 0.17% 2.48% 1.99% 3.06%
14 - 0.19% 2.13% 1.35% 2.58%
15 - 0.21% 1.78% 1.60% 1.93%
16 - 0.14% 2.00% 1.47% 2.44%
17 - 0.22% 1.73% 1.40% 2.31%
18 - 0.15% 1.50% 1.19% 2.09%
19 - 0.14% N/A N/A N/A
20 - 0.15% N/A N/A N/A
21 - 0.09% N/A N/A N/A
22 - 0.10% N/A N/A N/A
23 - 0.08% N/A N/A N/A
24 - 0.13% N/A N/A N/A
25 - 0.12% N/A N/A N/A
26 - 0.16% N/A N/A N/A
27 - 0.11% N/A N/A N/A
28 - 0.20% N/A N/A N/A
29 - 0.20% N/A N/A N/A
30 - 0.22% N/A N/A N/A
31 - 0.21% N/A N/A N/A
32 - 0.25% N/A N/A N/A
33 - 0.31% N/A N/A N/A
34 - 0.50% N/A N/A N/A

Influenza Outbreak Surveillance

In week 10, no outbreaks were reported.

To date this season (August 29, 2021 to March 12, 2022), 18 ILI outbreaks and no laboratory-confirmed influenza outbreaks have been reported. All ILI outbreaks have been reported in schools and/or daycares. The most recent laboratory-confirmed influenza outbreak occurred in week 24 (week ending June 13, 2020) of the 2019-2020 season.

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 10: 12 out of 13

Influenza Severe Outcomes Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In week 10, no influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote 2.

To date this season (August 29, 2021 to March 12, 2022), less than five influenza-associated hospitalizations were reported by participating provinces and territories with the most recent influenza-associated hospitalization reported in week 52 (week ending January 1, 2022).

Number of provinces and territories reporting in week 10: 8 out of 9

Pediatric Influenza Hospitalizations and Deaths

In week 10, no influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network.

To date this season (August 29, 2021 to March 12, 2022), eight 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 10, 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 29, 2021 to March 12, 2022), less than five influenza-associated adult (≥16 years of age) hospitalizations have been reported by the CIRN SOS network.

Influenza Strain Characterization

To date this season (August 29, 2021 to March 12, 2022), the National Microbiology Laboratory (NML) has characterized 41 influenza viruses (39 A(H3N2), 2 A(H1N1)) received from Canadian laboratories.

Influenza A(H3N2)

Genetic Characterization

Among the 39 influenza A(H3N2) viruses genetically characterized, sequence analysis of the HA gene of these viruses showed that they all belonged to genetic group 3C.2a1b.2a2.

A/Cambodia/e0826360/2020 (H3N2)-like virus is the influenza A(H3N2) component of the 2021-2022 Northern Hemisphere seasonal influenza vaccine and belongs to genetic group 3C.2a1b.2a1.

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

Antigenic Characterization

Among the 39 A(H3N2) viruses characterized:

Influenza A(H1N1)

Antigenic Characterization

Among the two A(H1N1) viruses characterized:

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

41 influenza viruses (39 A(H3N2) and 2 A(H1N1)) were tested for resistance to oseltamivir:

Zanamivir

41 influenza viruses (39 A(H3N2) and 2 A(H1N1)) were tested for resistance to zanamivir:

Influenza Vaccine Monitoring

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

Vaccine Coverage

The Seasonal Influenza Immunization Coverage Survey is an annual telephone survey conducted between January and February that collects information from Canadians on whether they received the annual seasonal influenza vaccine that season. Vaccine coverage is measured as the percentage of people who reported receiving the influenza vaccine in a specific influenza season.

In the 2021-22 influenza season, coverage was similar to the 2020-21 season at:

Table 1 – Influenza vaccine coverage among adults (n=3,502)Footnote * by risk groupFootnote and genderFootnote , Seasonal Influenza Vaccination Coverage Survey, Canada, September 2021 – February 2022
Age group (years) All Male Female
N Vaccine Coverage %
(95% CI)
N Vaccine Coverage %
(95% CI)
N Vaccine Coverage %
(95% CI)
All adults (≥18) 3487 38.7 (36.9-40.6) 1548 33.4 (30.8-36.0) 1914 43.9 (41.3-46.5)
18-64 2389 30.1 (28.0-32.2) 1079 24.9 (22.1-27.8) 1286 35.0 (31.9-38.1)
with chronic medical conditions 713 37.6 (33.6-41.7) 298 37.0 (31.0-43.1) 407 38.3 (32.9-43.8)
without chronic medical conditions 1658 26.8 (24.4-29.2) 769 19.9 (16.9-23.0) 873 33.7 (29.9-37.4)
≥65 1098 71.0 (68.1-74.0) 469 67.0 (62.2-71.8) 628 74.6 (70.9-78.3)
Table 1 Note *

18 people did not recall whether they had received the influenza vaccine and were excluded from coverage estimates.

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Table 1 Note †

11 people who were 18-64 years old did not disclose whether they had any chronic medical conditions (CMC) and were excluded from stratified analysis.

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Table 1 Note ‡

11 people did not disclose their gender and 9 people did not identify as male or female. They were excluded from stratified analysis.

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Vaccine Effectiveness

Within season influenza vaccine effectiveness (VE) estimates are typically available in February or March of each year. Given the low influenza circulation this season to date, VE estimates for Canada will not be available for the 2021-2022 season.

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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