FluWatch report: September 23, 2018 to October 6, 2018 (Weeks 39-40)

Overall Summary

  • Influenza activity remains at interseasonal levels across the country.
  • The majority of regions in Canada report no influenza activity.
  • All indicators of influenza activity are at low levels, as expected for this time of year.
  • Influenza A is the most common influenza virus circulating in Canada.
  • Influenza and other respiratory viruses are monitored weekly and results reported every Thursday in the Respiratory Virus Detections in Canada Report

Influenza/Influenza-like Illness Activity (geographic spread)

During week 40, the following influenza activity levels were reported (Figure 1):

  • Localized activity was reported in one region in Manitoba.
  • Sporadic activity was reported by 10 regions, in B.C(1), Alberta(5), Ontario(3), and Quebec(1).
  • No activity was reported by the majority of regions (36).
  • No data were reported by six regions.

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Organization: Public Health Agency of Canada

Date published: 2018-10-12

Figure 1 – Map of overall influenza/ILI activity by province and territory, Canada, week 2018-40

Figure 1
Figure 1 - Text Description
Influenza Surveillance Region Activity Level
Newfoundland - Central  No Activity
Newfoundland - Eastern  No Activity
Grenfell Labrador No Activity
Newfoundland - Western  No Activity
Prince Edward Island No Activity
Nova Scotia - Central (Zone 4) No Activity
Nova Scotia - Western (Zone 1) No Activity
Nova Scotia - Northern (Zone 2) No Activity
Nova Scotia - Eastern (Zone 3) No Activity
New Brunswick - Public Health Region 1 No Activity
New Brunswick - Public Health Region 2 No Activity
New Brunswick - Public Health Region 3 No Activity
New Brunswick - Public Health Region 4 No Activity
New Brunswick - Public Health Region 5 No Activity
New Brunswick - Public Health Region 6 No Activity
New Brunswick - Public Health Region 7 No Activity
Nord-est Québec Sporadic
Québec et Chaudieres-Appalaches No Activity
Centre-du-Québec No Activity
Montréal et Laval No Activity
Ouest-du-Québec No Activity
Montérégie  No Activity
Ontario - Central East Sporadic
Ontario - Central West Sporadic
Ontario - Eastern No Activity
Ontario - North East Sporadic
Ontario - North West  No Activity
Ontario - South West  No Activity
Ontario - Toronto No Activity
Manitoba - Interlake-Eastern  No Activity
Manitoba - Northern Regional No Activity
Manitoba - Prairie Mountain No Activity
Manitoba - South Localized
Manitoba - Winnipeg No Activity
Saskatchewan - North  No Data
Saskatchewan - Central No Data
Saskatchewan - South No Data
Alberta - North Zone Sporadic
Alberta - Edmonton Sporadic
Alberta - Central Zone  Sporadic
Alberta - Calgary Sporadic
Alberta - South Zone  Sporadic
British Columbia - Interior No Activity
British Columbia - Fraser  No Activity
British Columbia - Vancouver Coastal No Activity
British Columbia - Vancouver Island Sporadic
British Columbia - Northern No Activity
Yukon No Data
Northwest Territories - North No Data
Northwest Territories - South No Data
Nunavut - Baffin No Activity
Nunavut - Kivalliq No Activity
Nunavut - Kitimeot No Activity

Laboratory Confirmed Influenza Detections

In weeks 39 and 40, the following results were reported from sentinel laboratories across Canada (Figure 2 and Figure 3):

  • Overall, laboratory detections of influenza are at interseasonal levels.
  • A total of 73 laboratory detections of influenza were reported. Sixty-seven of these detections were influenza A.
  • The percentage of tests positive for influenza was 0.67% and  1.58% in weeks 39 and 40 respectively

To date this season, detailed information on age and type/subtype has been received for 83 laboratory-confirmed influenza cases (Table 1).

  • Adults 20-64 years of age represent the largest proportion of cases overall (61%)

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, 2018-35 to 2018-40

Figure 2

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

Figure 2 - Text Description
Report Week A(Unsubtyped) A(H3) A(H1)pdm09 Influenza B
35 3 2 7 0
36 4 7 4 0
37 3 2 3 1
38 6 3 2 3
39 11 5 1 3
40 17 7 26 3

Figure 3 – Cumulative numbers of positive influenza specimens by type/subtype and province/territory, Canada, weeks 2018-35 to 2018-40

Figure 3
Figure 3 - Text Description
Reporting
provincesTable Figure 3 - Footnote 1
Week (September 23, 2018 to October 6, 2018) Cumulative (August 26, 2018 to October 6, 2018)
Influenza A B Influenza A B A & B
Total
A
Total
A
(H1N1)pdm09
A
(H3N2)
A(UnS)Table Figure 3 - Footnote 3 B
Total
A
Total
A
(H1N1)pdm09
A
(H3N2)
A(UnS)Table Figure 3 - Footnote 3 B
Total
BC 9 2 3 4 1 25 6 8 11 1 26
AB 25 13 6 6 5 38 16 11 11 6 44
SK 0 0 0 0 0 7 0 2 5 0 7
MB 2 1 0 1 0 2 1 0 1 0 2
ON 1 0 0 1 0 17 9 5 3 3 20
QC 3 0 0 3 0 6 0 0 6 0 6
NB 1 0 0 1 0 1 0 0 1 0 1
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 0 0 0 0 0 0 0 0 0 0 0
YT 0 0 0 0 0 0 0 0 0 0 0
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 41 16 9 16 6 96 32 26 38 10 106
PercentageTable Figure 3 - Footnote 2 87% 39% 22% 39% 13% 91% 33% 27% 40% 9% 100%
Table Figure 3 - Footnote 1

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

Return to Table Figure 3 - Footnote 1 referrer

Table Figure 3 - Footnote 2

Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections.

Return to Table Figure 3 - Footnote 2 referrer

Table Figure 3 - Footnote UnS

Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available.

Return to first Table Figure 3 - Footnote 3 referrer

Discrepancies in values in Figures 2 and 3 may be attributable to differing data sources.

Cumulative data includes updates to previous weeks.

Table 1 - Cumulative numbers of positive influenza specimens by type, subtype and age-group reported through case-based laboratory reporting, Canada, weeks 2018-35 to 2018-40
Age groups (years) Cumulative (August 26, 2018 to October 6, 2018)
Influenza A B Influenza A and B
A Total A(H1) pdm09 A(H3) A (UnS)Footnote 1 Total # %
0-4 >10 5 <5 5 0 - -
5-19 7 <5 0 <5 <5 - -
20-44 >18 9 <5 9 <5 - -
45-64 25 10 6 9 <5 - -
65+ >6 <5 6 <5 <5 - -
Total 74 >24 >12 >23 9 - -
Tableau 1 - Note 1

UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available;

Return to Table 1 - Note 1

Syndromic/Influenza-like Illness Surveillance

Healthcare Professionals Sentinel Syndromic Surveillance

In week 40, 0.9% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 4). The percentage of visits for ILI is at interseasonal levels.

Figure 4 - Percentage of visits for ILI reported by sentinels by report week, Canada, weeks 2018-35 to 2018-40 Number of Sentinels Reporting in Week 40: 97

The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2012-13 to 2016-17

Figure 4
Figure 4 - Text Description
Report week 2018-19 Average Min Max
35 0,6% 0,8% 0,5% 1,2%
36 0,7% 0,8% 0,7% 1,0%
37 0,5% 0,9% 0,7% 1,0%
38 0,7% 1,1% 1,0% 1,4%
39 1,8% 1,1% 0,9% 1,4%
40 0,9% 1,3% 0,9% 1,6%

Participatory Syndromic Surveillance

In week 40, 1,758 participants reported to FluWatchers, of which 46 (3%) reported symptoms of cough and fever (Figure 5).

Among the 46 participants who reported fever and cough:

  • 11% consulted a healthcare professional
  • 54% reported days missed from work or school, resulting in a combined total of 81 missed days of work or school.

Figure 5 – Percentage of participants reporting cough and fever, Canada, week 2018-40

Number of Participants Reporting in Week 40: 1,758

Figure 5
Figure 5 - Text Description
Report week % cough and Fever
40 3%

Influenza Outbreak Surveillance

In weeks 39 and 40, no new influenza outbreaks were reported. One ILI outbreak was reported in week 39. To date this season, 14 ILI outbreaks have been reported. All outbreaks occurred in LTC facilities.

Severe Outcomes Influenza Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

To date this season, 8 influenza-associated hospitalizations were reported by participating provinces and territoriesFootnote 1.

Pediatric Influenza Hospitalizations and Deaths

Surveillance of laboratory-confirmed influenza associated pediatric (≤16 years of age) hospitalizations from the Immunization Monitoring Program Active (IMPACT) network has not yet begun for the 2018-19 season.

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 2018-19 season.

Influenza Strain Characterizations

Since September 1, 2018, the National Microbiology Laboratory (NML) has characterized  4 influenza viruses (2 A(H3N2) and 2 A(H1N1)) that were received from Canadian laboratories. 

Genetic Characterization of Influenza A (H3N2):

One influenza A(H3N2) virus did not grow to sufficient hemagglutination titer for antigenic characterization by hemagglutination inhibition (HI) assay. Therefore, NML has performed genetic characterization to determine the genetic group identity of this virus.

Sequence analysis of the HA gene of this virus showed that:

  • The A(H3N2) virus belonged to genetic group 3C.2a1

A/Singapore/INFIMH-16-0019/2016-like virus belongs to genetic group 3C.2a1 and is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.

Antigenic Characterization:

Influenza A(H3N2):

  • One influenza A(H3N2) virus was antigenically characterized as A/Singapore/INFIMH-16-0019/2016-like by HI testing using antiserum raised against egg-propagated A/Singapore/INFIMH-16-0019/2016.
  • A/Singapore/INFIMH-16-0019/2016 is the influenza A(H3N2) component of the 2018-19 Northern Hemisphere influenza vaccine.

Influenza A(H1N1):

Two A(H1N1) viruses characterized were antigenically similar to A/Michigan/45/2015, which is the influenza A(H1N1) component of the 2018-19 Northern Hemisphere influenza vaccine.

Antiviral Resistance

Antiviral Resistance – Amantadine:

Three influenza A (2 A(H3N2) and 1 A(H1N1)) viruses were tested for resistance to amantadine and it was found that:

  • The two A(H3N2) viruses tested were resistant to amantadine.
  • The one A(H1N1) virus was resistant to amantadine.

Antiviral Resistance – Oseltamivir:

Four influenza viruses (2 A(H3N2) and 2 A(H1N1))  were tested for resistance to oseltamivir and it was found that:

  • The two A(H3N2) viruses tested were sensitive to oseltamivir
  • The two A(H1N1) viruses tested were sensitive to oseltamivir

Antiviral Resistance – Zanamivir:

Four influenza viruses (2 A(H3N2) and 2 A(H1N1)) were tested for resistance to zanamivir and it was found that:

  • The two A(H3N2) viruses were sensitive to zanamivir.
  • The two A(H1N1) viruses were sensitive to zanamivir.

Notes: To learn more about definitions, descriptions and the FluWatch program in general, see the Overview of influenza monitoring in Canada page. For more information on the flu, see our Flu(influenza) web page.

This report is available on the Government of Canada Influenza webpage.
Ce rapport est disponible dans les deux langues officielles.

We would like to thank all the Fluwatch surveillance partners who are participating in this year's influenza surveillance program.

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