FluWatch report: September 22 to October 5, 2019 (Weeks 39 and 40)

Influenza/Influenza-like Illness Activity (geographic spread)

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

• 2 regions (4%) reported localized activity, within BC and YT.
• 8 regions (17%) reported sporadic activity, within BC, SK, ON and QC.

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	Sporadic
Que.	Montréal et Laval	Sporadic
Que.	Ouest-du-Québec	No Activity
Que.	Montérégie	No Activity
Ont.	Central East	Sporadic
Ont.	Central West	No Activity
Ont.	Eastern	No Activity
Ont.	North East	No Activity
Ont.	North West	No Activity
Ont.	South West	Sporadic
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 Activity
Sask.	Central	Sporadic
Sask.	South	No Activity
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	No Activity
B.C.	Vancouver Island	Localized
B.C.	Northern	Sporadic
Y.T.	Yukon	Localized
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 weeks 39 and 40, the following results were reported from sentinel laboratories across Canada (Figures 2 and 3):

• A total of 82 laboratory detections of influenza were reported, of which 94% (77) were influenza A.
• The percentage of tests positive for influenza remains at interseasonal levels, at 1.1% in week 39 and 1.2% in week 40.
• Influenza A(H3N2) accounted for 94% (30 of 32) subtyped influenza A detections during this 2-week period.

To date this season (weeks 35 to 40), detailed information on age and type/subtype has been received for 126 laboratory-confirmed influenza cases: 113 (90%) influenza A and 13 (10%) influenza B. Among the 63 subtyped influenza A detections, 89% of cases were A(H3N2). The majority of cases reported to date were in adults; 41% of cases were 20-64 years of age, and 42% were over 65 years of age.

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 - Text equivalent

Surveillance Week	A(Unsubtyped)	A(H3N2)	A(H1N1)pdm09	Influenza B	Percent Positive A	Percent Positive B
35	10	16	0	2	1.3	0.1
36	11	13	2	2	1.1	0.1
37	5	17	2	5	0.9	0.2
38	11	15	3	6	1.0	0.2
39	11	21	2	3	1.0	0.1
40	30	9	0	2	1.2	0.1

Figure 3 - Text equivalent

ProvincesTable Figure 3 - Footnote 1	Cumulative (August 25, 2019 to October 5, 2019)
	A Total	A(H1N1)pdm09	A(H3N2)	A(UnS)3	B Total	A & B Total
BC	71	4	44	23	0	71
AB	40	3	26	11	5	45
SK	8	0	0	8	0	8
MB	1	0	0	1	1	2
ON	24	1	13	10	7	31
QC	24	0	0	24	6	30
NB	4	1	1	2	1	5
NS	0	0	0	0	0	0
PEI	0	0	0	0	0	0
NL	0	0	0	0	0	0
YT	8	0	7	1	0	8
N.W.T	0	0	0	0	0	0
NU	0	0	0	0	0	0
Canada	180	9	91	80	20	200
PercentageTable Figure 3 - Footnote 2	90%	5%	51%	44%	10%	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

Syndromic / Influenza-like Illness Surveillance

Healthcare Professionals Sentinel Syndromic Surveillance

In week 39, 0.8% and in week 40, 1.3%, of visits to healthcare professionals were due to influenza-like illness (ILI) which is similar to the average for this time of year (Figure 4).

The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2014-2015 to 2018-2019

Figure 4 - Text equivalent

Surveillance Week	2019-20	Average	Min	Max
35	0.6%	0.6%	0.4%	0.9%
36	0.4%	0.6%	0.4%	0.9%
37	0.8%	0.7%	0.5%	1.0%
38	1.3%	0.7%	0.6%	1.0%
39	0.8%	0.9%	0.5%	1.2%
40	1.3%	1.2%	0.8%	1.7%
41	#N/A	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

FluWatchers reporting for the 2019-20 season began on October 7th, 2019. In week 40, 2,768 participants reported to FluWatchers, of which 59 (2.1%) reported symptoms of cough and fever (Figure 5).

Among the 59 participants who reported cough and fever:

• 14% consulted a healthcare professional;
• 73% reported days missed from work or school, resulting in a combined total of 97 missed days of work or school.

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

Figure 5 - Text equivalent

Surveillance Week	% cough and fever
40	2.1%

Online Figure – Geographic distribution of FluWatchers participants reporting cough and fever, Canada, week 2019-40

Click on the map to access the link

Influenza Outbreak Surveillance

In weeks 39 and 40, 3 laboratory-confirmed influenza outbreaks were reported in long-term care facilities. All outbreaks were due to influenza A. No ILI outbreaks were reported.

To date this season, a total of 3 laboratory-confirmed influenza outbreaks in long-term care facilities and two ILI outbreaks in schools and daycares have been reported.

Number of provinces and territories reporting in weeks 39 and 40: 12 out of 13

Severe Outcomes Influenza Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In weeks 39 and 40 less than five influenza-associated hospitalizations were reported by participating provinces and territories^{Footnote 1}.

To date this season, 7 influenza-associated hospitalizations were reported by participating provinces and territories^{Footnote 1}. All case except one were associated with influenza A. Less than five ICU admissions and no deaths have been reported.

Number of provinces and territories reporting in weeks 39 and 40: 8 out of 9

Pediatric Influenza Hospitalizations and Deaths

In weeks 39 and 40, no new pediatric (≤16 years of age) laboratory-confirmed influenza-associated hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network.

To date this season, fewer than five pediatric hospitalizations have been reported by the 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 2019-20 season.

Influenza Strain Characterizations

From September 1 to October 10, 2019, the National Microbiology Laboratory (NML) has characterized 5 influenza viruses (3 A(H3N2), 1 A(H1N1) and 1 influenza B) that were received from Canadian laboratories.

Influenza A(H3N2)

Over recent years, circulating strains of A(H3N2) have evolved, and are increasingly difficult to characterize by hemagglutination inhibition (HI) assay. Genetic characterization is established by sequencing the hemagglutinin (HA) gene of the influenza viruses to compare their genetic properties.

Antigenic Characterization:

• Two influenza A(H3N2) viruses were antigenically characterized as A/Kansas/14/2017-like by HI assay using antiserum raised against cell culture-propagated A Kansas/14/2017.

Genetic Characterization:

All three A(H3N2) viruses this season have been genetically characterized, based on sequence analysis of the HA gene.

• One A(H3N2) virus did not grow to sufficient hemagglutination titer for antigenic characterization by HI assay.
  • This virus belonged to genetic subclade 3C.2a1b.
• Two A(H3N2) viruses were antigenically characterized as A/Kansas/14/2017-like by HI testing.
  • These two viruses belonged to genetic group 3C.2a1b.

A/Kansas/14/2017 belongs to genetic group 3C.3a and is the influenza A(H3N2) component of the 2019-20 Northern Hemisphere influenza vaccine.

Influenza A(H1N1)

• One A(H1N1) virus characterized was antigenically similar to A/Brisbane/02/2018 by HI testing using antiserum raised against egg-propagated A/Brisbane/02/2018.

A/Brisbane/02/2018 is the influenza A(H1N1) component of the 2019-20 Northern Hemisphere influenza vaccine.

Influenza B

• One influenza B virus showed reduced titer with ferret antisera raised against cell culture-propagated B/Colorado/06/2017.
• Sequence analysis showed that the virus had a three amino acid deletion (162-164) in the HA gene.

The recommended influenza B components for the 2019-20 Northern Hemisphere influenza vaccine are B/Colorado/06/2017 (Victoria lineage) and B/Phuket/3073/2013 (Yamagata lineage). B/Phuket/3073/2013 is included in the quadrivalent influenza vaccine.

Antiviral Resistance

The National Microbiology Laboratory (NML) also tests influenza viruses received from Canadian laboratories for antiviral resistance.

Antiviral Resistance - Oseltamivir:

Seven influenza viruses (4 H3N2, 1 H1N1 and 2 B) were tested for resistance to oseltamivir and it was found that:

• All 7 influenza viruses were sensitive to oseltamivir.

Antiviral Resistance – Zanamivir:

Seven influenza viruses (4 H3N2, 1 H1N1 and 2 B) were tested for resistance to zanamivir and it was found that:

• All 7 influenza viruses were sensitive to zanamivir.

Antiviral Resistance – Amantadine:

High levels of resistance to amantadine persist among influenza A(H1N1) and influenza A(H3N2) viruses, therefore amantadine resistance results are not presented.

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 2019-20 season are anticipated to be available in February or March 2020.

Vaccine Effectiveness

Influenza vaccine effectiveness estimates for the 2019-20 season are anticipated to be available in February or March 2020.

Provincial and International Surveillance Links

• British Columbia – Influenza Surveillance; Vaccine Effectiveness Monitoring
• Alberta – Influenza surveillance
• Saskatchewan – Influenza Reports
• Manitoba – Seasonal Influenza Reports
• Ontario – Ontario Respiratory Pathogen Bulletin
• Québec – Système de surveillance de la grippe (available in French only)
• New Brunswick – Influenza Surveillance Reports
• Prince Edward Island – Influenza Summary
• Nova Scotia – Respiratory Watch Report
• Newfoundland and Labrador – Surveillance and Disease Reports
• Yukon – Information on Pandemic, Influenza, Seasonal Flu, Avian Flu and H1N1
• Northwest Territories – Influenza/ Flu Information
• Nunavut – Influenza Information
• World Health Organization – FluNet (Global Influenza Surveillance Network)
• Pan American Health Organization – Influenza situation report
• U.S. Centers for Disease Prevention & Control (CDC) - Weekly Influenza Summary Update
• ECDC – Surveillance reports and disease data on seasonal influenza
• United Kingdom – Weekly Influenza Activity Reports
• Hong Kong Centre for Health Protection - Flu Express
• Australia – Influenza Surveillance Report and Activity Updates
• New Zealand – Influenza Weekly Update

Notes

The data in the FluWatch report represent surveillance data available at the time of writing. All data are preliminary and may change as more reports 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.