FluWatch report: June 5 to June 11, 2022 (week 23)

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Organization: Public Health Agency of Canada

Published: 2022-06-17

Weekly Highlights

  • Influenza activity, now in the eighth week of Canada’s 2021/2022 late-onset seasonal epidemic, continues to decrease, but remains above the epidemic threshold. Influenza activity continues to be reported in most regions across the country.

Virologic

  • In week 22, 945 laboratory detections (926 influenza A and 19 influenza B) were reported.
  • Influenza A(H3N2) is the dominant subtype, representing 97% of sub-typed influenza A detections this season to date (August 29, 2021 to June 11, 2022).
  • From August 29, 2021 to June 11, 2022 (weeks 35 to 23), among detections with detailed age information, nearly half (49%) were in children and teenagers (ages 0 to 19 years).

Syndromic

  • The percentage of visits for influenza-like illness (ILI) was 1.1% in week 23. The percentage visits for ILI remains slightly above levels typical of this time of year.
  • The percentage of FluWatchers reporting fever and cough was 1.3% in week 23. The percentage of FluWatchers who reported cough and fever has remained steady in recent weeks.

Outbreaks

  • From August 29, 2021 to June 11, 2022 (weeks 35 to 23), 73 laboratory-confirmed influenza outbreaks have been reported. All laboratory-confirmed influenza outbreaks have occurred from week 11 (week of March 13 to 19, 2022) onwards.

Severe Outcomes

  • From August 29, 2021 to June 11, 2022 (weeks 35 to 22), 570 influenza-associated hospitalizations have been reported from participating provinces and territories.
  • The weekly number of influenza-associated pediatric hospitalizations reported by the IMPACT network has decreased in recent weeks, but remains above levels typical of this time of year.

Other Notes

  • The next scheduled FluWatch report (week 24) will be published June 24, 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 23, influenza activity was reported in almost all provinces and territories. Among the 41 regions reporting influenza activity, 78% reported sporadic activity and 22% reported localized activity (Figure 1).

Figure 1 – Map of influenza/ILI activity by province and territory, Canada, week 2022-23

Number of Regions Reporting in Week 23: 48 out of 53

Figure 1. Text version below.
Figure 1 - Text description
Province Influenza Surveillance Region Activity Level
N.L. Eastern Localized
N.L. Labrador-Grenfell Sporadic
N.L. Central Sporadic
N.L. Western Sporadic
P.E.I. Prince Edward Island Sporadic
N.S. Zone 1 - Western Sporadic
N.S. Zone 2 - Northern Sporadic
N.S. Zone 3 - Eastern Sporadic
N.S. Zone 4 - Central Sporadic
N.B. Region 1 Localized
N.B. Region 2 Localized
N.B. Region 3 Localized
N.B. Region 4 Localized
N.B. Region 5 No Activity
N.B. Region 6 Sporadic
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 Sporadic
Ont. Eastern Localized
Ont. North East Sporadic
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 Sporadic
Man. Southern Health No Activity
Sask. North Sporadic
Sask. Central Sporadic
Sask. South Sporadic
Alta. North Zone No Data
Alta. Edmonton No Data
Alta. Central Zone No Data
Alta. Calgary No Data
Alta. South Zone No Data
B.C. Interior Sporadic
B.C. Fraser Sporadic
B.C. Vancouver Coastal Sporadic
B.C. Vancouver Island Sporadic
B.C. Northern Sporadic
Y.T. Yukon Sporadic
N.W.T. North Sporadic
N.W.T. South Sporadic
Nvt. Qikiqtaaluk Sporadic
Nvt. Kivalliq Localized
Nvt. Kitimeot Localized

Laboratory-Confirmed Influenza Detections

In week 23, 945 laboratory detections (926 influenza A and 19 influenza B) were reported. The number of detections and the weekly percentage of tests positive for influenza continued to decrease this week, but remain above levels typically seen at this time of year and above the epidemic threshold.

The following results were reported from sentinel laboratories across Canada in week 23 (Figures 2 and 3):

To date this season (August 29, 2021 to June 11, 2022), 14,151 influenza detections were reported:

Detailed information on age and type/subtype has been received for 12,712 laboratory-confirmed influenza detections (Figure 4). Among the 12,712 detections, 5,954 (49%) were in individuals under 0-19 years old and 3,059 (25%) were in individuals 20-44 years old.

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, season 2021-2022

Number of Laboratories Reporting in Week 23: 31 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 3 0 0 0 0.0 0.0
36 1 0 0 0 0.0 0.0
37 0 4 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 1 9 0 10 0.1 0.1
46 3 8 0 9 0.1 0.1
47 4 11 0 12 0.1 0.1
48 10 7 0 28 0.2 0.2
49 28 6 0 9 0.2 0.1
50 19 12 1 4 0.2 0.0
51 25 12 1 6 0.2 0.0
52 10 12 1 2 0.1 0.0
1 9 12 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 1 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 5 2 1 2 0.1 0.0
9 8 6 2 0 0.1 0.0
10 7 10 1 0 0.2 0.0
11 16 9 0 1 0.3 0.0
12 46 36 3 0 0.9 0.0
13 121 106 1 0 1.5 0.0
14 217 152 0 1 2.5 0.0
15 346 199 0 2 3.8 0.0
16 845 263 4 2 7.0 0.0
17 1402 326 10 2 9.7 0.0
18 1677 421 2 2 11.3 0.0
19 1604 581 3 8 12.5 0.1
20 1106 555 6 12 10.3 0.1
21 1014 484 12 6 9.4 0.0
22 809 422 5 9 8.0 0.1
23 580 276 8 19 6.7 0.1
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0
#N/A 0 0 0 0 0.0 0.0

The shaded area indicates weeks where the positivity rate was at least 5% and a minimum of 15 positive tests were observed, signalling the period of seasonal influenza activity.

Figure 3: Comparison of the number of influenza tests and percentage of tests positive in Canada by week of report, 2021-2022 compared to previous seasons
Figure 3. Text version below.
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 7061 4996 1979 1311 1705
36 7939 5192 2208 1323 1707
37 9256 5335 2631 1778 2135
38 9725 6024 3039 1987 2502
39 9608 6707 3356 2365 2859
40 10699 7127 4078 2443 3134
41 10290 6817 4339 2673 3240
42 12383 6755 4649 2648 3526
43 13261 8227 4996 3084 3862
44 15353 9615 4966 2994 4020
45 17330 10748 5912 3117 4508
46 16221 11955 5589 3176 4564
47 16701 13103 6541 3587 5018
48 18356 18762 7416 3569 5645
49 19816 19649 8559 3836 6377
50 22397 16189 9464 4017 7155
51 28377 14059 11142 3487 8822
52 29528 12290 11338 4272 9184
1 28332 11681 14932 5371 12552
2 23595 14097 16104 5315 13289
3 19510 17002 15001 5270 11820
4 16409 15391 15414 5873 11441
5 15927 16607 16595 6739 11456
6 13843 12949 16121 8324 11339
7 13103 20727 14443 8074 10842
8 12142 21290 14024 7606 10865
9 11235 21891 14520 7507 10956
10 10704 20896 17681 7005 11084
11 10168 21220 12714 6435 9175
12 10754 23087 10431 5976 8238
13 11757 25811 9989 6063 7699
14 12637 26303 8830 4773 7046
15 13239 26284 7836 5090 6527
16 15435 26792 6826 5000 5890
17 17960 29154 6603 4440 5305
18 18525 22152 5640 4143 4780
19 17602 12725 5480 3680 4311
20 16473 9738 5097 3046 3862
21 15899 7442 4001 2577 3197
22 15489 6765 3790 2424 2944
23 13911 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
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 0.03 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 0.20 0.07 8.55 1.20 3.70
45 0.13 0.04 10.10 1.39 4.63
46 0.16 0.03 14.11 1.51 6.05
47 0.20 0.07 15.36 1.44 7.71
48 0.34 0.05 18.20 0.84 10.61
49 0.28 0.04 19.71 1.64 13.01
50 0.25 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 0.08 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 0.05 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 0.12 0.00 34.28 16.80 24.59
10 0.16 0.00 35.99 16.05 23.22
11 0.27 0.01 31.41 16.19 21.41
12 0.86 0.00 30.03 15.03 20.10
13 1.52 0.00 28.25 14.50 19.56
14 2.49 0.00 23.16 12.66 17.86
15 3.86 0.01 20.73 11.95 16.27
16 6.99 0.00 18.52 11.64 14.48
17 9.68 0.00 17.30 9.76 12.83
18 11.29 0.00 13.02 7.88 10.26
19 12.51 0.00 11.95 4.96 8.98
20 10.33 0.01 9.13 3.19 7.22
21 9.42 0.01 7.45 2.97 5.60
22 8.04 0.00 4.96 2.19 3.86
23 6.80 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

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 4 – Proportion of positive influenza specimens by type or subtype and age-group reported through case-based laboratory reporting, Canada
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 98.6% 1.4% 2579
5 to 19 99.4% 0.6% 3699
20 to 44 98.8% 1.2% 3187
45 to 64 98.5% 1.5% 1254
65+ 98.1% 1.9% 1993
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 4.1% 95.9% 367
5 to 19 3.8% 96.2% 547
20 to 44 2.4% 97.6% 540
45 to 64 1.1% 98.9% 181
65+ 1.1% 98.9% 348

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 weeks or previous seasons.

Due to different testing protocols of laboratories across Canada, influenza A subtype detection counts may not be included in total influenza A detection counts, as some subtype detections are not available through routine testing but are subsequently reported if further subtype testing is conducted. In these instances, subtype counts do not reflect influenza A detections intended to be captured by routine surveillance, and are excluded from total detections and percent positivity.

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.

Syndromic / Influenza-like Illness Surveillance

Healthcare Practitioners Sentinel Surveillance

In week 23, 1.1% of visits to healthcare professionals were due to influenza-like illness (ILI). The percentage of visits for ILI remains slightly above 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, 2021-2022

Number of Sentinels Reporting in Week 23: 44

Figure 5. Text version below.
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 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 #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%

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.

FluWatchers

In week 23, 11,035 participants reported to FluWatchers, of which 1.3% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who report cough and fever has remained steady in recent weeks.

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 138 participants who reported cough and fever:

The Northwest Territories had the highest participation rate this week (53 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 participants reporting fever and cough, Canada, 2021-2022

Number of Participants Reporting in Week 23: 11,035

Figure 6. Text version below.
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 0.64% 0.18% 2.58% 2.12% 3.11%
11 0.88% 0.16% 2.33% 1.89% 2.63%
12 1.16% 0.17% 2.60% 2.46% 2.82%
13 1.79% 0.17% 2.48% 1.99% 3.06%
14 2.26% 0.19% 2.13% 1.35% 2.58%
15 1.95% 0.21% 1.78% 1.60% 1.93%
16 1.90% 0.14% 2.00% 1.47% 2.44%
17 1.60% 0.22% 1.73% 1.40% 2.31%
18 1.39% 0.15% 1.50% 1.19% 2.09%
19 1.34% 0.14% N/A N/A N/A
20 1.18% 0.15% N/A N/A N/A
21 1.23% 0.09% N/A N/A N/A
22 1.16% 0.10% N/A N/A N/A
23 1.25% 0.08% N/A N/A N/A
24 #N/A 0.13% N/A N/A N/A
25 #N/A 0.12% N/A N/A N/A
26 #N/A 0.16% N/A N/A N/A
27 #N/A 0.11% N/A N/A N/A
28 #N/A 0.20% N/A N/A N/A
29 #N/A 0.20% N/A N/A N/A
30 #N/A 0.22% N/A N/A N/A
31 #N/A 0.21% N/A N/A N/A
32 #N/A 0.25% N/A N/A N/A
33 #N/A 0.31% N/A N/A N/A
34 #N/A 0.50% N/A N/A N/A

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

Influenza Outbreak Surveillance

In week 23, the following outbreaks were reported in Canada:

To date this season (August 29, 2021 to June 11, 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 territories1 reporting in week 23: 12 out of 13

1All 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.

Influenza Severe Outcomes Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In week 23, 9 influenza-associated hospitalizations were reported by participating provinces and territories2.

To date this season (August 29, 2021 to June 11, 2022) among participating provinces and territories:

Number of provinces and territories reporting in week 23: 8 out of 9

Pediatric Influenza Hospitalizations and Deaths

In week 23, 13 influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network (Figure 7). Following a sharp increase in week 18 (week ending May 7, 2022), the number of influenza-associated pediatric hospitalizations reported by the IMPACT network has decreased, but remains above levels typical of this time of year.

Figure 7 – Number of pediatric (≤16 years of age) hospitalizations reported by the IMPACT network, by week, Canada, 2021-2022
Figure 7. Text version below.
Figure 7 - Text description
Surveillance week 2021-2022 Average  Min Max
35 0 0 0 1
36 0 1 0 2
37 0 1 0 2
38 0 1 0 2
39 0 1 0 3
40 0 1 0 2
41 0 2 0 3
42 0 3 0 7
43 0 4 1 11
44 0 6 1 21
45 0 9 2 36
46 0 12 1 37
47 1 11 1 35
48 1 20 2 46
49 1 21 3 41
50 0 31 4 54
51 2 44 5 82
52 1 63 14 103
1 1 62 21 107
2 0 50 12 100
3 0 51 27 80
4 0 58 34 90
5 0 59 25 120
6 0 60 15 115
7 0 59 17 118
8 1 65 25 134
9 1 57 12 151
10 0 54 17 135
11 0 51 16 118
12 0 39 13 87
13 6 32 15 66
14 7 28 12 56
15 18 25 11 56
16 17 23 11 41
17 20 19 9 37
18 49 16 8 28
19 36 11 5 19
20 30 10 0 18
21 33 6 4 9
22 14 6 1 9
23 13 3 1 7
24 #N/A 3 1 6
25 #N/A 2 0 5
26 #N/A 1 0 3
27 #N/A 1 0 2
28 #N/A 1 0 2
29 #N/A 1 0 3
30 #N/A 1 0 1
31 #N/A 0 0 0
32 #N/A 0 0 0
33 #N/A 0 0 2
34 #N/A 1 0 2
Figure 8 - Cumulative numbers of pediatric hospitalizations (≤16 years of age) with influenza by age-group reported by the IMPACT network, Canada, 2021-2022
Figure #. Text version below.
Figure 8 - Text description
Age Group Total
0-5 mo 31
6-23 mo 50
2-4 yr 69
5-9 yr 55
10-16 yr 47

Adult Influenza Hospitalizations and Deaths

In week 23, 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 June 11, 2022), 27 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 June 11, 2022), the National Microbiology Laboratory (NML) has characterized 171 influenza viruses (166 A(H3N2), 5 A(H1N1)) received from Canadian laboratories.

Influenza A(H3N2)

Genetic Characterization

Among the 166 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 161 A(H3N2) viruses characterized:

Influenza A(H1N1)

Antigenic Characterization

Among the five 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

158 influenza viruses (153 A(H3N2) and 5 A(H1N1)) were tested for resistance to oseltamivir:

Zanamivir

158 influenza viruses (153 A(H3N2) and 5 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)* by risk group† and gender‡, 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)
Footnote *

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

Return to footnote * referrer

Footnote †

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.

Return to footnote referrer

Footnote ‡

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

Return to footnote referrer

Vaccine Effectiveness

Within season influenza vaccine effectiveness (VE) estimates are typically available in February or March of each year. Given the low and late onset of community circulation of influenza this season, 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.

Return to footnote 1 referrer

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.

Return to footnote 2 referrer

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