FluWatch report: September 11 to September 24, 2016 (weeks 37-38)

  • Influenza activity is at interseasonal levels with the majority regions of Canada reporting low or no influenza activity.
  • In week 38, localized activity was reported in three regions across three provinces (BC, AB, and ON).
  • A total of 73 positive influenza detections were reported in weeks 37 and 38; influenza A(H3N2) was the most common subtype detected.
  • In week 38, 1% of visits to sentinel healthcare professionals were due to ILI.
  • The first laboratory-confirmed influenza outbreak this season was reported in week 37. A total of five outbreaks were reported in weeks 37 and 38.
  • Low numbers of hospitalizations were reported in weeks 37 and 38.
  • For more information on the flu, see our Flu(influenza) web page.

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Organization: Public Health Agency of Canada

Date published: 2016-09-30

In week 38, a total of forty of regions in Canada reported no influenza activity. Sporadic influenza activity was reported in nine regions. For the first time this season, localized activity was reported. A total of three regions across Ontario, Alberta and British Columbia reported localized activity in week 38.  For more details on a specific region, click on the map.

Figure 1 - Map of overall influenza/ILI activity level by province and territory, Canada, Week 38
Figure 1
Figure 1 Legend
Note: Influenza/ILI activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates and reported outbreaks. Please refer to detailed definitions at the end of the report. Maps from previous weeks, including any retrospective updates, are available in the mapping feature found in the Weekly Influenza Reports.
Figure 1 - Text Description

In week 38, a total of forty of regions in Canada reported no influenza activity. Sporadic influenza activity was reported in nine regions. For the first time this season, localized activity was reported. A total of three regions across Ontario, Alberta and British Columbia reported localized activity in week 38.

The percentage of tests positive for influenza remained at interseasonal levels, ranging from 1.2% in week 37 to 1.9% in week 38. For data on other respiratory virus detections, see the Respiratory Virus Detections in Canada Report on the Public Health Agency of Canada (PHAC) website.

Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, 2016-17
Figure 2
The shaded area indicates weeks where the positivity rate was at least 5% and a minimum of 15 positive tests were observed, signaling the start and end of seasonal influenza activity.
Figure 2 - Text Description
Figure 2 - Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, 2016-17
Report Week A(Unsubtyped) A(H3) A(H1)pdm09 Influenza B
35 0 <5 0 0
36 <5 5 <5 9
37 6 17 0 <5
38 20 23 <5 <5
39 0 0 0 0
40 0 0 0 0
41 0 0 0 0
42 0 0 0 0
43 0 0 0 0
44 0 0 0 0
45 0 0 0 0
46 0 0 0 0
47 0 0 0 0
48 0 0 0 0
49 0 0 0 0
50 0 0 0 0
51 0 0 0 0
52 0 0 0 0
1 0 0 0 0
2 0 0 0 0
3 0 0 0 0
4 0 0 0 0
5 0 0 0 0
6 0 0 0 0
7 0 0 0 0
8 0 0 0 0
9 0 0 0 0
10 0 0 0 0
11 0 0 0 0
12 0 0 0 0
13 0 0 0 0
14 0 0 0 0
15 0 0 0 0
16 0 0 0 0
17 0 0 0 0
18 0 0 0 0
19 0 0 0 0
20 0 0 0 0
21 0 0 0 0
22 0 0 0 0
23 0 0 0 0
24 0 0 0 0
25 0 0 0 0
26 0 0 0 0
27 0 0 0 0
28 0 0 0 0
29 0 0 0 0
30 0 0 0 0
31 0 0 0 0
32 0 0 0 0
33 0 0 0 0
34 0 0 0 0

Nationally in weeks 37-38, there were 73 positive influenza tests reported. Influenza A(H3N2) was the most common subtype detected in weeks 37 and 38. Many regions across Canada continue to report no influenza detections (SK, MB, NB, NS, PE, NT, NU). 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 3 - Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, 2016-17
Figure 3
Figure 3 - Text Description
Figure 3 - Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, 2016-17
Reporting
provincesTable Figure 3 - Footnote 1
Weekly (September 11, 2016 to September 24, 2016) Cumulative (August 28, 2016 to September 24, 2016)
Influenza A B Influenza A B A & B
Total
A
Total
A
(H1)pdm09
A
(H3)
ATable Figure 3 - Footnote UnS B
Total
A
Total
A
(H1)pdm09
A
(H3)
ATable Figure 3 - Footnote UnS B
Total
BC >25 <5 18 7 <5 >29 <5 22 7 <5 34
AB >11 0 11 <5 <5 >13 0 13 <5 5 22
SK 0 0 0 0 0 0 0 0 0 0 0
MB 0 0 0 0 0 0 0 0 0 0 0
ON 15 0 10 5 <5 17 0 11 6 7 24
QC 8 0 0 8 <5 9 0 0 9 <5 >9
NB 0 0 0 0 0 0 0 0 0 0 0
NS 0 0 0 0 0 0 0 0 0 0 0
PE 0 0 0 0 0 0 0 0 0 0 0
NL <5 0 <5 0 0 <5 0 <5 0 0 <5
YT <5 0 0 <5 0 <5 0 0 <5 0 <5
NT 0 0 0 0 0 0 0 0 0 0 0
NU 0 0 0 0 0 0 0 0 0 0 0
Canada 66 <5 >39 25 7 76 <5 >46 27 16 92

To date this season, detailed information on age and type/subtype has been received for 81 cases. Adults aged 65+ accounted for the greatest proportion of influenza cases (Table 1).

Table 1 - Weekly and cumulative numbers of positive influenza specimens by type, subtype and age-group reported through case-based laboratory reporting Table 1 - Footnote 1, Canada, 2016-17
Age groups (years) Weekly (September 11, 2016 to September 24, 2016) Cumulative (August 28, 2016 to September 24, 2016)
Influenza A B Influenza A B Influenza A and B
A Total A(H1) pdm09 A(H3) ATable 1 - Footnote UnS Total A Total A(H1) pdm09 A(H3) ATable 1 - Footnote UnS Total # %
<5 6 0 0 6 0 6 0 0 6 0    
5-19 <5 0 <5 0 0 <5 0 <5 0 <5    
20-44 7 0 <5 <5 <5 >6 0 6 <5 6    
45-64 11 0 7 <5 <5 14 0 9 5 <5    
65+ 34 <5 21 12 <5 36 <5 23 12 <5    
Total >58 <5 33 26 5 69 <5 >38 >23 12    

Healthcare Professionals Sentinel Syndromic Surveillance

In week 38, 1% of visits to healthcare professionals were due to ILI. The ILI rate has remained constant since week 35.

Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, 2016-17
Number of Sentinels Reporting Week 38: 84
Figure 4
Delays in the reporting of data may cause data to change retrospectively. In BC, AB, and SK, data are compiled by a provincial sentinel surveillance program for reporting to FluWatch. Not all sentinel physicians report every week.
Figure 4 - Text Description
Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, 2016-17
Report week % Visits for ILI
35 0.99%
36 0.98%
37 0.99%
38 0.98%
39 0.00%
40 0.00%
41 0.00%
42 0.00%
43 0.00%
44 0.00%
45 0.00%
46 0.00%
47 0.00%
48 0.00%
49 0.00%
50 0.00%
51 0.00%
52 0.00%
1 0.00%
2 0.00%
3 0.00%
4 0.00%
5 0.00%
6 0.00%
7 0.00%
8 0.00%
9 0.00%
10 0.00%
11 0.00%
12 0.00%
13 0.00%
14 0.00%
15 0.00%
16 0.00%
17 0.00%
18 0.00%
19 0.00%
20 0.00%
21 0.00%
22 0.00%
23 0.00%
24 0.00%
25 0.00%
26 0.00%
27 0.00%
28 0.00%
29 0.00%
30 0.00%
31 0.00%
32 0.00%
33 0.00%
34 0.00%

Are you a primary healthcare practitioner (General Practitioner, Nurse Practitioner or Registered Nurse) interested in becoming a FluWatch sentinel?
Please visit our Influenza Sentinel page for more details.

In weeks 37-38, four laboratory confirmed influenza outbreaks were reported. The first outbreak this season was reported in a long term care facility (LTCF) in week 37. Of the three outbreaks with known types or subtypes, one outbreak was due to influenza A (H3N2) and two were due to influenza A (unsubtyped).

Figure 5 - Overall number of new laboratory-confirmed influenza outbreaksFigure 5 - Footnote 1 by report week, Canada, 2016-17
Figure 5
Figure 5 - Text Description
Figure 5 - Overall number of new laboratory-confirmed influenza outbreaks by report week, Canada, 2016-17
Report week Hospitals Long Term Care Facilities Other
35 0 0 0
36 0 0 0
37 0 2 0
38 1 1 1
39 0 0 0
40 0 0 0
41 0 0 0
42 0 0 0
43 0 0 0
44 0 0 0
45 0 0 0
46 0 0 0
47 0 0 0
48 0 0 0
49 0 0 0
50 0 0 0
51 0 0 0
52 0 0 0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
6 0 0 0
7 0 0 0
8 0 0 0
9 0 0 0
10 0 0 0
11 0 0 0
12 0 0 0
13 0 0 0
14 0 0 0
15 0 0 0
16 0 0 0
17 0 0 0
18 0 0 0
19 0 0 0
20 0 0 0
21 0 0 0
22 0 0 0
23 0 0 0
24 0 0 0
25 0 0 0
26 0 0 0
27 0 0 0
28 0 0 0
29 0 0 0
30 0 0 0
31 0 0 0
32 0 0 0
33 0 0 0
34 0 0 0

In weeks 37-38, less than five influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote *. To date this season, no ICU admissions or deaths have been reported.

Table 2 - Cumulative number of hospitalizations, ICU admissions and deaths by age and influenza type reported by participating provinces and territories, Canada 2016-17
Age Groups (years) Cumulative (August 28, 2016 to September 24, 2016)
Hospitalizations ICU Admissions Deaths
Influenza A Total Influenza B Total Total [# (%)] Influenza A and B Total % Influenza A and B Total %
0-4 0 0 0 (0%) 0 0% 0 0%
5-19 <5 0 <5 (50%) 0 0% 0 0%
20-44 0 0 0 (0%) 0 0% 0 0%
45-64 0 <5 0 (0%) 0 0% 0 0%
65+ <5 <5 <5 (50%) 0 0% 0 0%
Total <5 <5 <5 (100%) 0 0% 0 0%

Pediatric Influenza Hospitalizations and Deaths

To date this season, less than five laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network.

During the 2016-17 influenza season, the National Microbiology Laboratory (NML) has characterized two influenza viruses, both influenza B.

Table 3 - Influenza strain characterizations, Canada, 2016-17
Strain Characterization ResultsTable 3 - Footnote 1 Count Description
Influenza B
B/Brisbane/60/2008-like
(Victoria lineage)
2 Viruses antigenically similar to B/Brisbane/60/2008, the influenza B component of the 2016-17 Northern Hemisphere’s trivalent and quadrivalent influenza vaccine

During the 2016-17 season, the National Microbiology Laboratory (NML) has tested two influenza viruses for resistance to oseltamivir and zanamivir. Both viruses were sensitive to oseltamivir and zanamivir (Table 4).

Table 4 - Antiviral resistance by influenza virus type and subtype, Canada, 2016-17
Virus type and subtype Oseltamivir Zanamivir Amantadine
# tested # resistant (%) # tested # resistant (%) # tested # resistant (%)
A (H3N2) 0 0 (0%) 0 0 (0%) 0 0 (0%)
A (H1N1) 0 0 (0%) 0 0 (0%) 0 0 (0%)
B 2 0 (0%) 2 0 (0%) N/ATable 4 - Footnote * N/ATable 4 - Footnote *
TOTAL 2 0 (0%) 2 0 (0%) 0 0 (0%)

Abbreviations: Newfoundland/Labrador (NL), Prince Edward Island (PE), New Brunswick (NB), Nova Scotia (NS), Quebec (QC), Ontario (ON), Manitoba (MB), Saskatchewan (SK), Alberta (AB), British Columbia (BC), Yukon (YT), Northwest Territories (NT), Nunavut (NU).

Influenza-like-illness (ILI): Acute onset of respiratory illness with fever and cough and with one or more of the following - sore throat, arthralgia, myalgia, or prostration which is likely due to influenza. In children under 5, gastrointestinal symptoms may also be present. In patients under 5 or 65 and older, fever may not be prominent.

ILI/Influenza outbreaks

Schools:
Greater than 10% absenteeism (or absenteeism that is higher (e.g. >5-10%) than expected level as determined by school or public health authority) which is likely due to ILI.
Note: it is recommended that ILI school outbreaks be laboratory confirmed at the beginning of influenza season as it may be the first indication of community transmission in an area.
Hospitals and residential institutions:
two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case. Institutional outbreaks should be reported within 24 hours of identification. Residential institutions include but not limited to long-term care facilities (LTCF) and prisons.
Workplace:
Greater than 10% absenteeism on any day which is most likely due to ILI.
Other settings:
two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case; i.e. closed communities.

Note that reporting of outbreaks of influenza/ILI from different types of facilities differs between jurisdictions.

Influenza/ILI activity level

1 = No activity: no laboratory-confirmed influenza detections in the reporting week, however, sporadically occurring ILI may be reported

2 = Sporadic: sporadically occurring ILI and lab confirmed influenza detection(s) with no outbreaks detected within the influenza surveillance region Footnote

3 = Localized:

  1. evidence of increased ILIFootnote * and
  2. lab confirmed influenza detection(s) together with
  3. outbreaks in schools, hospitals, residential institutions and/or other types of facilities occurring in less than 50% of the influenza surveillance regionFootnote

4 = Widespread:

  1. evidence of increased ILIFootnote * and
  2. lab confirmed influenza detection(s) together with
  3. outbreaks in schools, hospitals, residential institutions and/or other types of facilities occurring in greater than or equal to 50% of the influenza surveillance regionFootnote

Note: ILI data may be reported through sentinel physicians, emergency room visits or health line telephone calls.

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