FluWatch report: May 29 to June 4, 2022 (week 22)
Organization: Public Health Agency of Canada
Published: 2022-06-10
Related Topics
Weekly Highlights
- Influenza activity, now in the seventh 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 almost all regions of all provinces and territories.
Virologic
- In week 22, 1,329 laboratory detections (1,320 influenza A and 9 influenza B) were reported.
- Influenza A(H3N2) is the dominant strain among sub-typed infections, representing 98% of sub-typed influenza A infections this season to date.
- 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 22. The percentage visits for ILI slightly exceeds the pre-pandemic levels typical of this time of year.
- The percentage of FluWatchers reporting fever and cough was 1.1% in week 22.
Outbreaks
- From August 29, 2021 to June 4, 2022 (weeks 35 to 22), 70 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, at a relatively stable rate.
Severe Outcomes
- From August 29, 2021 to June 4, 2022 (weeks 35 to 22), 549 influenza-associated hospitalizations have been reported from participating provinces and territories.
- 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.
Other Notes
- The next scheduled FluWatch report (week 23) will be published June 17, 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
- 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 22, influenza activity was reported in almost all provinces and territories. Among the 45 regions reporting influenza activity, 78% reported sporadic activity and 22% reported localized activity (Figure 1).
Number of Regions Reporting in Week 22: 53 out of 53
Figure 1 - Text description
Province | Influenza Surveillance Region | Activity Level |
---|---|---|
N.L. | Eastern | Localized |
N.L. | Labrador-Grenfell | Localized |
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 | Sporadic |
N.B. | Region 4 | Localized |
N.B. | Region 5 | No Activity |
N.B. | Region 6 | No Activity |
N.B. | Region 7 | No Activity |
Que. | Nord-est | Sporadic |
Que. | Québec et Chaudieres-Appalaches | Sporadic |
Que. | Centre-du-Québec | Sporadic |
Que. | Montréal et Laval | Sporadic |
Que. | Ouest-du-Québec | Sporadic |
Que. | Montérégie | Sporadic |
Ont. | Central East | Localized |
Ont. | Central West | Localized |
Ont. | Eastern | Localized |
Ont. | North East | Sporadic |
Ont. | North West | Sporadic |
Ont. | South West | Sporadic |
Ont. | Toronto | Sporadic |
Man. | Northern Regional | Sporadic |
Man. | Prairie Mountain | No Activity |
Man. | Interlake-Eastern | No Activity |
Man. | Winnipeg | No Activity |
Man. | Southern Health | No Activity |
Sask. | North | Sporadic |
Sask. | Central | Sporadic |
Sask. | South | Sporadic |
Alta. | North Zone | Sporadic |
Alta. | Edmonton | Sporadic |
Alta. | Central Zone | Sporadic |
Alta. | Calgary | Sporadic |
Alta. | South Zone | Sporadic |
B.C. | Interior | Sporadic |
B.C. | Fraser | Sporadic |
B.C. | Vancouver Coastal | Sporadic |
B.C. | Vancouver Island | Sporadic |
B.C. | Northern | Sporadic |
Y.T. | Yukon | No Activity |
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 22, 1,329 laboratory detections (1,320 influenza A and 9 influenza B) were reported. After increasing sharply since the beginning of April, 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 22 (Figures 2 and 3):
- The weekly percentage of tests positive for influenza was 8.5% and is above expected pre-pandemic1 levels (2.2 to 5.0%).
- A total of 15,567 tests for influenza were performed. The number of weekly tests performed is above the weekly pre-pandemic1 average of weekly 2,944 tests.
- Among subtyped influenza A detections, 98% (189 out of 193) were influenza A(H3N2).
To date this season (August 29, 2021 to June 4, 2022), 13,681 influenza detections were reported:
- 99% (13,520), were influenza A.
- Among subtyped influenza A detections (2,842), influenza A(H3N2) accounted for 98% of detections.
- The total number of influenza detections are lower than what we have seen historically pre-pandemic1, where an average of 46,656 influenza detections were reported at this point in the season.
Detailed information on age and type/subtype has been received for 12,089 laboratory-confirmed influenza detections (Figure 4). Among the 12,089 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.
Number of Laboratories Reporting in Week 22: 32 out of 34
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 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 | 0.1 | 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 | 0.2 | 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 | 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 | 11 | 0 | 0 | 0.2 | 0.0 |
11 | 18 | 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 | 844 | 264 | 4 | 2 | 7.0 | 0.0 |
17 | 1403 | 325 | 10 | 2 | 9.6 | 0.0 |
18 | 1847 | 316 | 2 | 2 | 11.6 | 0.0 |
19 | 1905 | 386 | 2 | 8 | 13.0 | 0.1 |
20 | 1408 | 336 | 6 | 12 | 10.7 | 0.1 |
21 | 1286 | 346 | 11 | 6 | 10.1 | 0.0 |
22 | 1070 | 189 | 4 | 9 | 8.5 | 0.1 |
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 | 9316 | 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 | 17546 | 10748 | 5912 | 3117 | 4508 |
46 | 16418 | 11955 | 5589 | 3176 | 4564 |
47 | 16917 | 13103 | 6541 | 3587 | 5018 |
48 | 18531 | 18762 | 7416 | 3569 | 5645 |
49 | 19974 | 19649 | 8559 | 3836 | 6377 |
50 | 22543 | 16189 | 9464 | 4017 | 7155 |
51 | 28471 | 14059 | 11142 | 3487 | 8822 |
52 | 29555 | 12290 | 11338 | 4272 | 9184 |
1 | 28418 | 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 | 12180 | 21290 | 14024 | 7606 | 10865 |
9 | 11282 | 21891 | 14520 | 7507 | 10956 |
10 | 10752 | 20896 | 17681 | 7005 | 11084 |
11 | 10207 | 21220 | 12714 | 6435 | 9175 |
12 | 10808 | 23087 | 10431 | 5976 | 8238 |
13 | 11802 | 25811 | 9989 | 6063 | 7699 |
14 | 12698 | 26303 | 8830 | 4773 | 7046 |
15 | 13311 | 26284 | 7836 | 5090 | 6527 |
16 | 15505 | 26792 | 6826 | 5000 | 5890 |
17 | 18013 | 29154 | 6603 | 4440 | 5305 |
18 | 18650 | 22152 | 5640 | 4143 | 4780 |
19 | 17755 | 12725 | 5480 | 3680 | 4311 |
20 | 16630 | 9738 | 5097 | 3046 | 3862 |
21 | 16170 | 7442 | 4001 | 2577 | 3197 |
22 | 15567 | 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 |
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 | 0.15 | 0.03 | 14.11 | 1.51 | 6.05 |
47 | 0.19 | 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 | 0.28 | 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 | 2.47 | 0.00 | 23.16 | 12.66 | 17.86 |
15 | 3.84 | 0.01 | 20.73 | 11.95 | 16.27 |
16 | 6.96 | 0.00 | 18.52 | 11.64 | 14.48 |
17 | 9.65 | 0.00 | 17.30 | 9.76 | 12.83 |
18 | 11.56 | 0.00 | 13.02 | 7.88 | 10.26 |
19 | 13.00 | 0.00 | 11.95 | 4.96 | 8.98 |
20 | 10.73 | 0.01 | 9.13 | 3.19 | 7.22 |
21 | 10.09 | 0.01 | 7.45 | 2.97 | 5.60 |
22 | 8.54 | 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 |
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.
Figure 4 - Text description
Age Group | Proportion of Influenza A | Proportion of Influenza B | Total Number Influenza Detections |
---|---|---|---|
0 to 4 | 98.5% | 1.5% | 2447 |
5 to 19 | 99.4% | 0.6% | 3507 |
20 to 44 | 98.9% | 1.1% | 3059 |
45 to 64 | 98.6% | 1.4% | 1187 |
65+ | 98.5% | 1.5% | 1889 |
Age Group | Proportion of A(H1N1) | Proportion of A(H3N2) | Total Number of Subtyped Influenza Detections |
---|---|---|---|
0 to 4 | 4.0% | 96.0% | 327 |
5 to 19 | 3.6% | 96.4% | 498 |
20 to 44 | 2.0% | 98.0% | 508 |
45 to 64 | 1.2% | 98.8% | 167 |
65+ | 1.2% | 98.8% | 338 |
Syndromic / Influenza-like Illness Surveillance
Healthcare Practitioners Sentinel Surveillance
In week 22, 1.1% of visits to healthcare professionals were due to influenza-like illness (ILI). In recent weeks, the percentage of visits for ILI has decreased, but remains slightly above pre-pandemic 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.
Number of Sentinels Reporting in Week 22: 38
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 | 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 | 1.1% | 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 22, 11,165 participants reported to FluWatchers, of which 1.1% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who report cough and fever has decreased 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 127 participants who reported cough and fever:
- 20% consulted a healthcare professional;
- 72% reported days missed from work or school, resulting in a combined total of 334 missed days of work or school (average of 3.7 days);
If you are interested in becoming a FluWatcher, sign up today.
Number of Participants Reporting in Week 22: 11,165
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 | 0.64% | 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 | 1.14% | 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 22, the following outbreaks were reported in Canada:
- 2 laboratory-confirmed influenza outbreaks in long-term care facilities
- 2 ILI outbreaks in schools
To date this season (August 29, 2021 to June 4, 2022):
- 70 laboratory-confirmed influenza outbreaks have been reported
- 31 were in long-term care facilities
- 30 were in facilities categorized as‘other’
- 1 was in a school/day care
- 3 were in remote or isolated communities
- 5 were in acute care facilities
- All outbreaks were due to influenza A, of which 33 were due to influenza A(H3N2), 2 were due to influenza A(H1N1), and the remaining were influenza A unsubtyped
- 92 ILI outbreaks have been reported
- All but two 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, and even COVID-19. Many respiratory viruses in addition to the flu commonly circulate during the fall and winter, and can cause clusters of cases with respiratory illness which could be captured as ILI.
Number of provinces and territoriesFootnote 1 reporting in week 22: 13 out of 13
Influenza Severe Outcomes Surveillance
Provincial/Territorial Influenza Hospitalizations and Deaths
In week 22, 39 influenza-associated hospitalizations and 3 ICU admission were reported by participating provinces and territoriesFootnote 2.
To date this season (August 29, 2021 to June 4, 2022) among participating provinces and territories:
- 549 influenza-associated hospitalizations were reported
- All but three hospitalizations were due to influenza A.
- Of the hospitalizations for which subtype was reported (286), 99.9% were associated with influenza A(H3N2).
- The greatest proportion of hospitalizations (40%) were in adults 65 years of age and older.
- 50 influenza-associated ICU admissions and 15 influenza-associated deaths were reported.
Number of provinces and territories reporting in week 22: 9 out of 9
Pediatric Influenza Hospitalizations and Deaths
In week 22, 14 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.
To date this season (August 29, 2021 to June 4, 2022):
- 240 pediatric influenza-associated hospitalizations have been reported
- 144 (60%) were among children under the age of 5 years of age (Figure 8).
- 238 (99%) were associated with influenza A
- 19 pediatric influenza-associated intensive care unit (ICU) admissions have been reported.
Figure 7 - Text description
Surveillance week | 2020-2021 | Average | Min | Max |
---|---|---|---|---|
35 | #N/A | 0 | 0 | 1 |
36 | #N/A | 1 | 0 | 2 |
37 | #N/A | 1 | 0 | 2 |
38 | #N/A | 1 | 0 | 2 |
39 | #N/A | 1 | 0 | 3 |
40 | #N/A | 1 | 0 | 2 |
41 | #N/A | 2 | 0 | 3 |
42 | #N/A | 3 | 0 | 7 |
43 | #N/A | 4 | 1 | 11 |
44 | #N/A | 6 | 1 | 21 |
45 | #N/A | 9 | 2 | 36 |
46 | #N/A | 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 | 21 | 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 |
Figure 8 - Text description
Age Group | Total |
---|---|
0-5 mo | 31 |
6-23 mo | 47 |
2-4 yr | 66 |
5-9 yr | 53 |
10-16 yr | 43 |
Adult Influenza Hospitalizations and Deaths
In week 22, 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 4, 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 4, 2022), the National Microbiology Laboratory (NML) has characterized 156 influenza viruses (151 A(H3N2), 5 A(H1N1)) received from Canadian laboratories.
Influenza A(H3N2)
Genetic Characterization
Among the 132 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 151 A(H3N2) viruses characterized:
- 40 viruses were antigenically similar to A/Cambodia/e0826360/2020 (H3N2)-like virus
- 111 showed reduced titres with antisera raised against egg-grown A/Cambodia/e0826360/2020 (H3N2)-like virus.
Influenza A(H1N1)
Antigenic Characterization
Among the five A(H1N1) viruses characterized:
- Four 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
144 influenza viruses (139 A(H3N2) and 5 A(H1N1)) were tested for resistance to oseltamivir:
- All influenza viruses were sensitive to oseltamivir.
Zanamivir
144 influenza viruses (139 A(H3N2) and 5 A(H1N1)) 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 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:
- 30% among adults aged 18 to 64 years.
- 27% among adults aged 18-64 without chronic medical conditions.
- 38% among adults aged 18-64 with chronic medical conditions.
- 71% among seniors (aged 65 years and older).
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) |
|
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.
- 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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