FluWatch report: October 4 to October 10, 2020 (week 41) 

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Organization: Public Health Agency of Canada

Date published: 2020-10-10

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Overall Summary

  • Testing for influenza continues at elevated levels; however, influenza activity remains below average for this time of year.
  • During week 41, one influenza-like-illness (ILI) outbreak was reported in a school or daycare. To date, 44 ILI outbreaks have been reported in these settings which is higher than typically reported in these settings for this time of year. These elevated levels are not unexpected and are a signal of public health effectively leveraging existing flu surveillance systems to monitor respiratory viral illness in schools.
  • Influenza surveillance indicators may be influenced by the COVID-19 pandemic, including changes in healthcare-seeking behaviour, impacts of public health measures and influenza testing capacity. Current data should be interpreted with consideration to this context. See the COVID-19 Epidemiology update for information on COVID-19 cases in Canada.
  • FluWatch has resumed weekly reporting. Weekly reporting of laboratory detections of respiratory viruses continues year-round via our Respiratory Virus Detections Surveillance System.

Influenza/Influenza-like Illness (ILI) Activity (geographic spread)

During week 41, one region reported sporadic influenza 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 2020-41

Number of Regions Reporting in Week 41: 50 out of 53

Figure 1. Text equivalent follows.

Figure 1 - Text equivalent
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 No Activity
Que. Ouest-du-Québec No Activity
Que. Montérégie No Activity
Ont. Central East No Activity
Ont. Central West Sporadic
Ont. Eastern No Activity
Ont. North East No Activity
Ont. North West No Activity
Ont. South West No Activity
Ont. Toronto No Activity
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 No Activity
Alta. Central Zone No Activity
Alta. Calgary No Activity
Alta. South Zone No Activity
B.C. Interior No Activity
B.C. Fraser No Activity
B.C. Vancouver Coastal No Activity
B.C. Vancouver Island No Activity
B.C. Northern No Activity
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 41, no laboratory detections of influenza were (Figure 2). Despite elevated levels of testing for influenza, the percentage of laboratory tests positive for influenza has remained at exceptionally low levels throughout the period of March to October. In week 41, 6,488 tests for influenza were performed at reporting laboratories, which is double the average for this week over the past 6 seasons. The percentage of tests positive for influenza in week 41 was 0%, compared to 1.7% during the past 6 seasons.

The 2019-20 influenza season in Canada ended abruptly in mid-March, concurrent with the implementation of public health measures to reduce the spread of COVID-19. 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 Figure 2 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, 2020-35 to 2020-41

Figure 2

Number of laboratories reporting in week 41: 31 out of 35

Figure 2 - Text equivalent
Surveillance Week A(Unsubtyped) A(H3N2) A(H1N1) Influenza B Percent Positive A Percent Positive B
35 0 0 0 1 0.0 0.0
36 0 0 0 2 0.0 0.0
37 0 0 0 2 0.0 0.0
38 1 0 0 5 0.0 0.1
39 0 0 0 0 0.0 0.0
40 0 0 0 0 0.0 0.0
41 0 0 0 0 0.0 0.0

Figure 3 - Distribution of positive influenza specimens by type/subtype and province/territoryFootnote *, Canada, weeks 2020-35 to 2020-41

There is insufficient data for weeks 35-41 to present influenza detections by type/subtype and province/territory.

Footnote *

Specimens from NWT, YT, and Nvt are sent to reference laboratories in other provinces.

Return to footnote * referrer

Syndromic / Influenza-like Illness Surveillance

Healthcare Professionals Sentinel Syndromic Surveillance

In week 41, 0.47% of visits to healthcare professionals were due to influenza-like illness (ILI) which is similar to previous weeks, and continues to be lower than average compared to recent seasons. To date this season the proportion of visits for ILI was the lowest observed for this period compared to the past six seasons (Figure 4). This trend should be interpreted with caution as there have been changes in healthcare seeking behavior of individuals and a smaller number of sentinels reporting in recent weeks compared to previous seasons.

Figure 4 – Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2020-35 to 2020-41

Number of participants reporting in week 41: 51

Figure 4

The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2020 - 2021

Figure 4 - Text equivalent
Surveillance Week 2019-2020 Average Min Max
35 0.1% 0.6% 0.4% 0.9%
36 0.3% 0.6% 0.4% 0.9%
37 0.4% 0.7% 0.5% 1.0%
38 0.4% 0.7% 0.6% 1.0%
39 0.4% 0.9% 0.5% 1.2%
40 0.3% 1.2% 0.8% 1.7%
41 0.5% 1.7% 0.8% 2.8%
42 #N/A 1.6% 1.2% 2.1%
43 #N/A 1.2% 0.8% 1.7%
44 #N/A 1.2% 0.7% 1.7%
45 #N/A 1.2% 0.9% 1.5%
46 #N/A 1.4% 1.2% 1.8%
47 #N/A 1.6% 1.1% 2.2%
48 #N/A 1.5% 1.1% 2.2%
49 #N/A 1.7% 1.0% 2.8%
50 #N/A 1.5% 1.1% 1.7%
51 #N/A 1.9% 1.4% 2.7%
52 #N/A 2.0% 1.0% 3.1%
1 #N/A 3.4% 1.9% 5.4%
2 #N/A 3.4% 1.8% 5.7%
3 #N/A 2.3% 1.3% 3.7%
4 #N/A 2.0% 1.1% 2.9%
5 #N/A 2.1% 1.4% 3.1%
6 #N/A 2.4% 1.4% 4.0%
7 #N/A 2.4% 0.9% 3.5%
8 #N/A 2.3% 0.8% 3.4%
9 #N/A 2.3% 0.9% 3.1%
10 #N/A 2.0% 1.0% 2.8%
11 #N/A 1.9% 1.1% 2.8%
12 #N/A 1.6% 0.6% 2.6%
13 #N/A 1.6% 1.1% 2.6%
14 #N/A 1.7% 1.1% 3.0%
15 #N/A 1.3% 0.9% 1.9%
16 #N/A 1.2% 0.8% 1.7%
17 #N/A 1.2% 0.7% 1.7%
18 #N/A 1.3% 0.5% 2.0%
19 #N/A 0.9% 0.6% 1.3%
20 #N/A 1.1% 0.6% 1.5%
21 #N/A 0.9% 0.5% 1.3%
22 #N/A 0.7% 0.3% 1.0%
23 #N/A 0.8% 0.6% 1.0%
24 #N/A 0.7% 0.6% 1.0%
25 #N/A 0.6% 0.4% 0.8%
26 #N/A 0.8% 0.5% 1.4%
27 #N/A 0.6% 0.5% 0.7%
28 #N/A 0.7% 0.5% 1.3%
29 #N/A 0.9% 0.6% 1.7%
30 #N/A 0.6% 0.2% 0.9%
31 #N/A 0.4% 0.2% 0.6%
32 #N/A 0.8% 0.3% 1.2%
33 #N/A 0.7% 0.4% 1.3%
34 #N/A 0.7% 0.4% 1.5%

FluWatchers

In week 41, 10,091 participants reported to FluWatchers. A total of 42 participants (0.42%) reported symptoms of cough and fever (Figure 5). The percentage of participants reporting cough and fever is at very low levels and may be a direct effect of individual and public health measures enacted to reduce the spread of COVID-19. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

If you are interested in becoming a FluWatcher, sign up today.

Figure 5 - Percentage of participants reporting fever and cough, Canada, weeks 2020-35 to 2020-41

Number of participants reporting in week 41: 10,091

Figure 5. Text equivalent follows.
Figure 5 - Text equivalent
Surveillance Week 2020-2021 Average  Min Max
35 0.22% N/A N/A N/A
36 0.21% N/A N/A N/A
37 0.38% N/A N/A N/A
38 0.29% N/A N/A N/A
39 0.45% N/A N/A N/A
40 0.49% 2.51% 2.18% 2.71%
41 0.42% 2.18% 1.81% 2.57%
42 0.00% 1.80% 1.61% 2.03%
43 0.00% 1.87% 1.49% 2.18%
44 0.00% 1.57% 1.39% 1.78%
45 0.00% 1.83% 1.42% 2.32%
46 0.00% 1.83% 1.22% 2.15%
47 0.00% 1.93% 1.44% 2.39%
48 0.00% 2.43% 1.67% 3.35%
49 0.00% 2.56% 1.97% 3.16%
50 0.00% 2.91% 2.12% 3.79%
51 0.00% 3.18% 2.53% 3.95%
52 0.00% 3.98% 2.81% 5.38%
1 0.00% 3.84% 2.85% 4.76%
2 0.00% 2.94% 1.90% 3.93%
3 0.00% 3.25% 2.35% 4.84%
4 0.00% 3.12% 2.13% 4.23%
5 0.00% 3.19% 2.62% 3.59%
6 0.00% 3.47% 2.76% 4.28%
7 0.00% 3.18% 2.58% 3.79%
8 0.00% 3.09% 2.54% 3.65%
9 0.00% 2.81% 2.38% 3.53%
10 0.00% 2.58% 2.12% 3.11%
11 0.00% 2.33% 1.89% 2.63%
12 0.00% 2.60% 2.46% 2.82%
13 0.00% 2.48% 1.99% 3.06%
14 0.00% 2.13% 1.35% 2.58%
15 0.00% 1.78% 1.60% 1.93%
16 0.00% 2.00% 1.47% 2.44%
17 0.00% 1.73% 1.40% 2.31%
18 0.00% 1.50% 1.19% 2.09%
19 0.00% N/A N/A N/A
20 0.00% N/A N/A N/A
21 0.00% N/A N/A N/A
22 0.00% N/A N/A N/A
23 0.00% N/A N/A N/A
24 0.00% N/A N/A N/A
25 0.00% N/A N/A N/A
26 0.00% N/A N/A N/A
27 0.00% N/A N/A N/A
28 0.00% N/A N/A N/A
29 0.00% N/A N/A N/A
30 0.00% N/A N/A N/A
31 0.00% N/A N/A N/A
32 0.00% N/A N/A N/A
33 0.00% N/A N/A N/A
34 0.00% N/A N/A N/A
Online Figure - Geographic distribution of FluWatchers participants reporting cough and fever, Canada, week 2020-41

Click on the map to access the link

map

Influenza Outbreak Surveillance

In week 41, one influenza-like-illness (ILI) outbreak was reported in a school or daycare setting. No other influenza or ILI outbreaks were reported in any other settings.

To date this season, 44 influenza-like-illness (ILI) outbreaks have been reported. All outbreaks have been in schools and/or daycares and most were reported in weeks 39 and 40. No influenza or ILI outbreaks have been reported in any other settings. Outbreaks of ILI in schools and daycares are identified based on whether greater than 10% absenteeism due to ILI has been reported in these settings. Although the number of ILI outbreaks in schools and daycares reported is higher compared to the same time period in the previous two seasons, this is not unexpected given changes to outbreak surveillance, specifically increased vigilance in schools to monitor and report abseentism 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 rhinovirus and even COVID-19. Rhinovirus commonly circulates during the fall, 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 Report.

Number of provinces and territories reporting in week 41Footnote 1: 11 out of 13

Footnote 1

All Provinces and Territories (PTs) participate in FluWatch’s outbreak surveillance system. This outbreak system monitors influenza and ILI outbreaks in long-term care facilities, 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.

Return to footnote 1 referrer

Severe Outcomes Influenza Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In week 41, no influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote 1. To date no influenza-associated hospitalizations were reported by participating provinces and territories.

Number of provinces and territories reporting in week 41: 8 out of 9

Footnote 1

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.

Return to footnote 1 referrer

Pediatric Influenza Hospitalizations and Deaths

In week 41, no influenza-associated hospitalizations were reported. To date this season, less than five pediatric (≤16 years of age) hospitalizations with influenza were reported by the Immunization Monitoring Program Active (IMPACT) network.

Adult Influenza Hospitalizations and Deaths

Surveillance of laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network has not yet begun for the 2020-21 season.

Influenza Strain Characterizations

Due to the very low influenza circulation to date this season, the National Microbiology Laboratory has not yet received influenza viruses which were collected during the 2020-21 season for strain characterization.

Antiviral Resistance

Due to the very low influenza circulation to date this season, the National Microbiology Laboratory has not yet received influenza viruses which were collected during the 2020-21 season for antiviral resistance testing.

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 2020-21 season are anticipated to be available in February or March 2021.

Vaccine Effectiveness

Influenza vaccine effectiveness estimates are typically available in February or March of each year; this may be delayed for the 2020-21 season if low influenza circulation continues.

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