FluWatch report: November 6 to November 12, 2022 (week 45)

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 45, three regions in one province (Alta.) reported widespread activity, eleven regions in four provinces (N.S., N.B., Ont., and Sask.) reported localized activity and 19 regions in nine provinces and territories reported sporadic influenza activity (N.L., P.E.I., N.S., N.B., Ont., Man., Sask., Alta., and N.W.T.) (Figure 1).

Number of Regions Reporting in Week 45: 40 out of 53

Figure 1 - Text description

Province	Influenza Surveillance Region	Activity Level
N.L.	Eastern	Sporadic
N.L.	Labrador-Grenfell	No Activity
N.L.	Central	Sporadic
N.L.	Western	No Activity
P.E.I.	Prince Edward Island	Sporadic
N.S.	Zone 1 - Western	Sporadic
N.S.	Zone 2 - Northern	Sporadic
N.S.	Zone 3 - Eastern	Localized
N.S.	Zone 4 - Central	Sporadic
N.B.	Region 1	Localized
N.B.	Region 2	Localized
N.B.	Region 3	Localized
N.B.	Region 4	Sporadic
N.B.	Region 5	Sporadic
N.B.	Region 6	No Activity
N.B.	Region 7	No Activity
Que.	Nord-est	No Data
Que.	Québec et Chaudieres-Appalaches	No Data
Que.	Centre-du-Québec	No Data
Que.	Montréal et Laval	No Data
Que.	Ouest-du-Québec	No Data
Que.	Montérégie	No Data
Ont.	Central East	Localized
Ont.	Central West	Localized
Ont.	Eastern	Localized
Ont.	North East	Sporadic
Ont.	North West	Sporadic
Ont.	South West	Localized
Ont.	Toronto	Localized
Man.	Northern Regional	Sporadic
Man.	Prairie Mountain	Sporadic
Man.	Interlake-Eastern	Sporadic
Man.	Winnipeg	Sporadic
Man.	Southern Health	Sporadic
Sask.	North	Sporadic
Sask.	Central	Localized
Sask.	South	Localized
Alta.	North Zone	Widespread
Alta.	Edmonton	Widespread
Alta.	Central Zone	Widespread
Alta.	Calgary	Sporadic
Alta.	South Zone	Sporadic
B.C.	Interior	No Data
B.C.	Fraser	No Data
B.C.	Vancouver Coastal	No Data
B.C.	Vancouver Island	No Data
B.C.	Northern	No Data
Y.T.	Yukon	No Activity
N.W.T.	North	No Activity
N.W.T.	South	Sporadic
Nvt.	Qikiqtaaluk	No Data
Nvt.	Kivalliq	No Data
Nvt.	Kitimeot	No Data

Laboratory-Confirmed Influenza Detections

In week 45, a total of 3,909 laboratory detections (3,897 influenza A and 12 influenza B) were reported as we progress through the 3rd week of the national influenza epidemic.

The following results were reported from sentinel laboratories across Canada in week 45 (Figures 2 and 3):

• The weekly percentage of tests positive for influenza increased from 10.9% in week 44 to 15.8% in week 45 and is above expected pre-pandemic levels.
• Among subtyped influenza A detections, 97% (1,785) were influenza A(H3N2) and 3% (56) were influenza A(H1N1).
• Among detections for which age information was reported (2,151), 1,215 (56%) of detections were in individuals aged 0-19 years old.

To date this season (August 28, 2022 to November 12, 2022):

• 8,273 influenza detections were reported, of which 99% (8,218) were influenza A and among subtyped influenza A detections (4,461), influenza A(H3N2) accounted for 95% of detections.
• 4,892 laboratory-confirmed influenza detections with age information were reported, of which 2,813 (58%) were in individuals aged 0-19 years old (Figure 4).

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 45: 32 out of 34

Figure 2 - Text description

Surveillance Week	A(Unsubtyped)	A(H3N2)	A(H1N1)	Influenza B	Percent Positive A	Percent Positive B
35	12	10	2	3	0.2	0.0
36	9	5	1	5	0.1	0.0
37	19	9	3	2	0.2	0.0
38	26	34	20	3	0.5	0.0
39	44	53	22	5	0.7	0.0
41	120	110	20	1	1.5	0.0
42	214	204	11	9	2.4	0.1
43	407	595	23	6	5.6	0.0
44	997	1342	51	5	10.8	0.0
45	1846	1807	56	12	15.6	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.

The epidemic threshold is 5% tests positive for influenza. When it is exceeded, and a minimum of 15 weekly influenza detections are reported, a seasonal influenza epidemic is declared.

Figure 3 - Text description

Surveillance Week	Percentage of tests positive, 2022-2023	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	0.2	0.0	0.0	1.9	0.1	0.8
36	0.2	0.0	0.0	2.3	0.3	1.1
37	0.3	0.0	0.0	1.8	0.4	1.0
38	0.5	0.0	0.0	2.4	0.5	1.3
39	0.7	0.0	0.0	2.9	0.7	1.7
40	1.0	0.0	0.0	2.3	1.1	1.7
41	1.5	0.1	0.0	3.0	1.3	1.7
42	2.5	0.1	0.0	3.4	0.9	2.2
43	5.6	0.1	0.0	5.3	0.8	2.8
44	10.8	0.2	0.1	8.5	1.2	3.7
45	15.7	0.1	0.0	10.1	1.4	4.6
46	N/A	0.2	0.0	14.1	1.5	6.1
47	N/A	0.2	0.1	15.4	1.4	7.7
48	N/A	0.3	0.1	18.2	0.8	10.6
49	N/A	0.3	0.0	19.7	1.6	13.0
50	N/A	0.3	0.0	27.0	2.4	16.8
51	N/A	0.2	0.0	29.1	3.3	20.1
52	N/A	0.1	0.0	34.5	4.3	24.5
1	N/A	0.1	0.0	31.7	5.8	23.4
2	N/A	0.1	0.0	29.1	7.1	23.0
3	N/A	0.1	0.0	30.1	12.2	23.6
4	N/A	0.1	0.0	29.5	15.9	24.0
5	N/A	0.0	0.0	30.6	19.6	24.9
6	N/A	0.1	0.0	32.4	17.9	25.0
7	N/A	0.0	0.0	32.5	16.3	25.1
8	N/A	0.1	0.0	32.9	17.5	25.1
9	N/A	0.1	0.0	34.3	16.8	24.6
10	N/A	0.2	0.0	36.0	16.0	23.2
11	N/A	0.3	0.0	31.4	16.2	21.4
12	N/A	0.9	0.0	30.0	15.0	20.1
13	N/A	1.5	0.0	28.3	14.5	19.6
14	N/A	2.5	0.0	23.2	12.7	17.9
15	N/A	3.9	0.0	20.7	11.9	16.3
16	N/A	7.0	0.0	18.5	11.6	14.5
17	N/A	9.7	0.0	17.3	9.8	12.8
18	N/A	11.3	0.0	13.0	7.9	10.3
19	N/A	12.6	0.0	11.9	5.0	9.0
20	N/A	10.4	0.0	9.1	3.2	7.2
21	N/A	9.8	0.0	7.4	3.0	5.6
22	N/A	8.4	0.0	5.0	2.2	3.9
23	N/A	7.0	0.0	4.4	0.9	2.9
24	N/A	5.0	0.0	4.4	0.8	2.2
25	N/A	3.0	0.0	3.9	0.6	1.9
26	N/A	2.3	0.0	3.1	0.7	1.8
27	N/A	1.2	0.0	2.8	0.4	1.5
28	N/A	0.8	0.0	1.8	0.4	0.9
29	N/A	0.7	0.0	1.6	0.5	1.1
30	N/A	0.4	0.0	1.5	0.5	0.9
31	N/A	0.3	0.0	1.9	0.6	1.1
32	N/A	0.2	0.0	1.2	0.5	0.9
33	N/A	0.2	0.0	1.7	0.4	0.9
34	N/A	0.2	0.0	1.6	0.4	0.9

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 seasons.

Due to different testing protocols of laboratories across Canada, some influenza A subtype detection counts may not be included in total influenza A detection counts and percent positivity calculations.

Figure 4 - Text description

a) Proportion of influenza A and B by age-group

Age Group	Proportion of Influenza A	Proportion of Influenza B	Total Number Influenza Detections
0 to 4	99.4%	0.6%	929
5 to 19	99.7%	0.3%	1884
20 to 44	98.8%	1.2%	805
45 to 64	99.8%	0.2%	447
65+	99.3%	0.7%	827

b) Proportion of subtyped influenza A(H1N1) and A(H3N2) by age-group

Age Group	Proportion of A(H1N1)	Proportion of A(H3N2)	Total Number of Subtyped Influenza Detections
0 to 4	3.4%	96.6%	700
5 to 19	3.2%	96.8%	1286
20 to 44	5.4%	94.6%	569
45 to 64	10.3%	89.7%	290
65+	5.1%	94.9%	566

Syndromic / Influenza-like Illness Surveillance

Healthcare Practitioners Sentinel Surveillance

In week 45, 2.6% of visits to healthcare professionals were due to influenza-like illness (ILI). The percentage of visits for ILI is well above expected levels for 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 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 45: 40

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	2022-2023	2021-2022	2020-2021	Average	Min	Max
35	0.6%	0.6%	0.1%	0.6%	0.4%	0.9%
36	0.9%	1.2%	0.2%	0.6%	0.4%	0.9%
37	0.7%	0.6%	0.4%	0.7%	0.5%	1.0%
38	0.8%	0.9%	0.3%	0.7%	0.6%	1.0%
39	1.0%	1.0%	0.4%	0.9%	0.5%	1.2%
40	0.7%	0.5%	0.2%	1.2%	0.8%	1.7%
41	1.9%	1.1%	0.4%	1.7%	0.8%	2.8%
42	1.4%	1.2%	0.5%	1.6%	1.2%	2.1%
43	1.6%	0.9%	0.3%	1.2%	0.8%	1.7%
44	1.5%	0.6%	0.3%	1.2%	0.7%	1.7%
45	2.6%	1.0%	0.4%	1.2%	0.9%	1.5%
46	N/A	0.9%	0.8%	1.4%	1.2%	1.8%
47	N/A	0.7%	0.3%	1.6%	1.1%	2.2%
48	N/A	1.1%	0.5%	1.5%	1.1%	2.2%
49	N/A	0.9%	0.5%	1.7%	1.0%	2.8%
50	N/A	1.1%	0.4%	1.5%	1.1%	1.7%
51	N/A	1.7%	0.5%	1.9%	1.4%	2.7%
52	N/A	1.5%	0.5%	2.0%	1.0%	3.1%
1	N/A	2.1%	0.7%	3.4%	1.9%	5.4%
2	N/A	1.6%	0.4%	3.4%	1.8%	5.7%
3	N/A	1.4%	0.2%	2.3%	1.3%	3.7%
4	N/A	0.9%	0.3%	2.0%	1.1%	2.9%
5	N/A	1.0%	0.2%	2.1%	1.4%	3.1%
6	N/A	0.7%	0.5%	2.4%	1.4%	4.0%
7	N/A	0.7%	0.3%	2.4%	0.9%	3.5%
8	N/A	0.8%	0.2%	2.3%	0.8%	3.4%
9	N/A	0.7%	0.2%	2.3%	0.9%	3.1%
10	N/A	0.9%	0.2%	2.0%	1.0%	2.8%
11	N/A	0.6%	0.2%	1.9%	1.1%	2.8%
12	N/A	0.8%	0.3%	1.6%	0.6%	2.6%
13	N/A	1.2%	0.4%	1.6%	1.1%	2.6%
14	N/A	1.1%	0.2%	1.7%	1.1%	3.0%
15	N/A	1.2%	0.3%	1.3%	0.9%	1.9%
16	N/A	1.5%	0.3%	1.2%	0.8%	1.7%
17	N/A	1.3%	0.4%	1.2%	0.7%	1.7%
18	N/A	1.8%	0.5%	1.3%	0.5%	2.0%
19	N/A	1.7%	0.3%	0.9%	0.6%	1.3%
20	N/A	1.5%	0.5%	1.1%	0.6%	1.5%
21	N/A	1.4%	0.3%	0.9%	0.5%	1.3%
22	N/A	1.0%	0.3%	0.7%	0.3%	1.0%
23	N/A	1.1%	0.2%	0.8%	0.6%	1.0%
24	N/A	1.3%	0.2%	0.7%	0.6%	1.0%
25	N/A	1.0%	0.2%	0.6%	0.4%	0.8%
26	N/A	0.8%	0.2%	0.8%	0.5%	1.4%
27	N/A	1.7%	0.3%	0.6%	0.5%	0.7%
28	N/A	1.0%	0.1%	0.7%	0.5%	1.3%
29	N/A	0.9%	0.3%	0.9%	0.6%	1.7%
30	N/A	1.3%	0.2%	0.6%	0.2%	0.9%
31	N/A	0.9%	0.2%	0.4%	0.2%	0.6%
32	N/A	0.9%	0.2%	0.8%	0.3%	1.2%
33	N/A	0.8%	0.3%	0.7%	0.4%	1.3%
34	N/A	1.0%	0.5%	0.7%	0.4%	1.5%

FluWatchers

In week 45, 10,940 participants reported to FluWatchers, of which 2.9% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever has increased in recent weeks and remains well above expected levels typical of this time of year.

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 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 320 participants who reported cough and fever:

• 16% consulted a healthcare professional;
• 80% reported days missed from work or school, resulting in an average of 2.8 missed days from work or school among those 254 participants.

The Northwest Territories had the highest participation rate this week (62 participants per 100,000 population) and the neighbourhood with postal code, K0A had the highest number of participants (153). See what is happening in your neighbourhood! Downloadable datasets are also available on Open Maps.

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

Number of Participants Reporting in Week 45: 10,940

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	2022-2023	2021-2022	2020-2021	Average	Min	Max
35	1.3%	0.2%	0.2%	N/A	N/A	N/A
36	1.2%	0.3%	0.2%	N/A	N/A	N/A
37	1.6%	0.5%	0.4%	N/A	N/A	N/A
38	1.8%	0.5%	0.3%	N/A	N/A	N/A
39	2.3%	0.5%	0.4%	N/A	N/A	N/A
40	2.4%	0.6%	0.5%	2.5%	2.2%	2.7%
41	2.0%	0.5%	0.4%	2.2%	1.8%	2.6%
42	2.0%	0.4%	0.3%	1.8%	1.6%	2.0%
43	2.3%	0.5%	0.2%	1.9%	1.5%	2.2%
44	2.6%	0.5%	0.3%	1.6%	1.4%	1.8%
45	2.9%	0.5%	0.3%	1.8%	1.4%	2.3%
46	N/A	0.4%	0.3%	1.8%	1.2%	2.2%
47	N/A	0.6%	0.3%	1.9%	1.4%	2.4%
48	N/A	0.5%	0.3%	2.4%	1.7%	3.4%
49	N/A	0.4%	0.2%	2.6%	2.0%	3.2%
50	N/A	0.6%	0.1%	2.9%	2.1%	3.8%
51	N/A	1.0%	0.2%	3.2%	2.5%	3.9%
52	N/A	1.5%	0.1%	4.0%	2.8%	5.4%
1	N/A	1.1%	0.1%	3.8%	2.9%	4.8%
2	N/A	1.0%	0.2%	2.9%	1.9%	3.9%
3	N/A	0.8%	0.1%	3.3%	2.3%	4.8%
4	N/A	0.6%	0.1%	3.1%	2.1%	4.2%
5	N/A	0.6%	0.2%	3.2%	2.6%	3.6%
6	N/A	0.5%	0.1%	3.5%	2.8%	4.3%
7	N/A	0.4%	0.2%	3.2%	2.6%	3.8%
8	N/A	0.5%	0.1%	3.1%	2.5%	3.6%
9	N/A	0.5%	0.1%	2.8%	2.4%	3.5%
10	N/A	0.6%	0.2%	2.6%	2.1%	3.1%
11	N/A	0.9%	0.2%	2.3%	1.9%	2.6%
12	N/A	1.2%	0.2%	2.6%	2.5%	2.8%
13	N/A	1.8%	0.2%	2.5%	2.0%	3.1%
14	N/A	2.3%	0.2%	2.1%	1.3%	2.6%
15	N/A	1.9%	0.2%	1.8%	1.6%	1.9%
16	N/A	1.9%	0.1%	2.0%	1.5%	2.4%
17	N/A	1.6%	0.2%	1.7%	1.4%	2.3%
18	N/A	1.4%	0.2%	1.5%	1.2%	2.1%
19	N/A	1.3%	0.1%	N/A	N/A	N/A
20	N/A	1.2%	0.2%	N/A	N/A	N/A
21	N/A	1.2%	0.1%	N/A	N/A	N/A
22	N/A	1.2%	0.1%	N/A	N/A	N/A
23	N/A	1.2%	0.1%	N/A	N/A	N/A
24	N/A	1.3%	0.1%	N/A	N/A	N/A
25	N/A	1.3%	0.1%	N/A	N/A	N/A
26	N/A	1.8%	0.2%	N/A	N/A	N/A
27	N/A	2.0%	0.1%	N/A	N/A	N/A
28	N/A	1.9%	0.2%	N/A	N/A	N/A
29	N/A	1.8%	0.2%	N/A	N/A	N/A
30	N/A	1.6%	0.2%	N/A	N/A	N/A
31	N/A	1.3%	0.2%	N/A	N/A	N/A
32	N/A	1.2%	0.3%	N/A	N/A	N/A
33	N/A	1.4%	0.3%	N/A	N/A	N/A
34	N/A	1.3%	0.5%	N/A	N/A	N/A

Influenza Outbreak Surveillance

In week 45, 17 laboratory-confirmed influenza outbreaks were reported in Canada (11 in acute care facilities, 5 in long-term care facilities (LTC), and 1 in a facility categorized as 'other'). All outbreaks were due to influenza A. An additional 4 ILI outbreaks were reported in schools/daycares.

To date this season (August 28, 2022 to November 12, 2022):

• 59 laboratory-confirmed influenza outbreaks have been reported
• 23 were in LTC facilities (39%)
• 17 were in facilities categorized as 'other' (29%)
• 15 were in acute care facilities (25%)
• 4 were in schools/daycares (7%)
• All but one outbreak were due to influenza A
• 15 ILI outbreaks have been reported
• All 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, COVID-19, or a mixture of viruses. 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 territories^{Footnote 1} reporting in week 45: 10 out of 13

Figure 7 - Text description

Surveillance Week	Acute Care Facilities	Long Term Care Facilities	Other	Schools and Daycares	Remote and/or Isolated Communities
35	0	0	1	0	0
36	0	1	0	0	0
37	0	0	0	0	0
38	0	0	0	0	0
39	0	1	0	0	0
40	0	2	2	0	0
41	1	0	1	0	0
42	3	0	1	0	0
43	0	3	5	3	0
44	0	11	6	1	0
45	11	5	1	0	0

Influenza Severe Outcomes Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In week 45, 186 influenza-associated hospitalizations and 14 ICU admissions were reported by participating provinces and territories^{Footnote 2}.

To date this season 394 influenza-associated hospitalizations were reported (August 28, 2022 to November 12, 2022) by participating provinces and territories

• 99% of the hospitalizations were associated with influenza A.
• Of the cases with subtype information (302), 92% were associated with influenza A(H3N2)
• The highest cumulative hospitalization rates up to week 45 were among children under 5 years of age (15/100,000 population) and adults 65 years of age and older (11/100,000 population).

To date this season (August 28, 2022 to November 12, 2022), 32 ICU admissions and 9 influenza-associated deaths were reported.

Number of provinces and territories reporting in week 45: 9 out of 9

Figure 8 - Text description

Surveillance Week	0-4 yrs	5-19 yrs	20-44 yrs	45-64 yrs	65+ yrs	Overall
35	0.2	-	0.0	0.0	0.1	0.0
36	0.2	-	0.0	0.0	0.1	0.1
37	0.2	-	0.0	0.1	0.4	0.1
38	0.2	-	0.0	0.1	0.4	0.1
39	0.2	-	0.0	0.1	0.6	0.2
40	0.2	-	0.1	0.2	0.6	0.2
41	0.2	0.1	0.1	0.2	1.1	0.3
42	0.4	0.1	0.2	0.4	1.3	0.4
43	2.2	1.1	0.4	0.6	2.5	1.0
44	7.6	3.1	0.8	1.6	5.1	2.5
45	14.5	5.1	1.5	2.9	10.5	4.7

Pediatric Influenza Hospitalizations and Deaths

In week 45, 146 influenza-associated pediatric (≤16 years of age) hospitalizations and 16 ICU admissions were reported by the Immunization Monitoring Program Active (IMPACT) network. The number of weekly influenza-associated hospitalizations is well above levels typical of this time of year and is at levels typically seen at the peak of the influenza season (Figure 9). All hospitalisations reported in week 45 were associated to influenza A.

To date this season (August 28, 2022 to November 12, 2022), 282 pediatric influenza-associated hospitalizations and 33 ICU admissions have been reported. Children aged between 2-4 years and 5-9 years account for nearly 60% of the reported pediatric hospitalizations (Figure 10).

Figure 9 - Text description

Surveillance week	2022-2023	2021-2022	Average	Min	Max
35	0	0	0	0	1
36	1	0	1	0	2
37	0	0	1	0	2
38	1	0	1	0	2
39	1	0	1	0	3
40	1	0	1	0	2
41	4	0	2	0	3
42	7	0	3	0	7
43	40	0	4	1	11
44	72	0	6	1	21
45	146	0	9	2	36

Figure 10 - Text description

Age Group	Total
0-5 mo	14
6-23 mo	37
2-4 yr	84
5-9 yr	80
10-16 yr	67

Influenza Strain Characterization

Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 17 influenza viruses (16 A(H3N2), 1 A(H1N1)) received from Canadian laboratories.

Genetic Characterization of Influenza A(H3N2)

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

Sequence analysis of the HA gene of the virus showed that it belonged to genetic group 3C.2a1b.2a2.

A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine and belongs to genetic group 3C.2a1b.2a2.

Antigenic Characterization

Influenza A(H3N2)

• 11 influenza A (H3N2) viruses were characterized as antigenically similar to A/Darwin/6/2021 (H3N2)-like virus with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus.
  • A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine. 
• Of the 11 influenza A (H3N2) viruses characterized, 10 viruses belonged to genetic group 3C.2a1b.2a2. Sequencing is pending for the remaining virus.

Influenza A(H1N1)

• One A(H1N1) virus was characterized as antigenically similar to A/Wisconsin/588/2019-like with ferret antisera produced against cell-propagated A/Wisconsin/588/2019. 
  • A/Wisconsin/588/2019 is the influenza A/H1N1 component of the 2022-23 Northern Hemisphere influenza vaccine.

Antiviral Resistance

The NML also tests influenza viruses received from Canadian laboratories for antiviral resistance.

Oseltamivir

16 influenza viruses (15 A(H3N2) and 1 A(H1N1)) were tested for resistance to oseltamivir and it was found that:

• All influenza viruses were sensitive to oseltamivir.

Zanamivir

16 influenza viruses (15 A(H3N2) and 1 A(H1N1)) were tested for resistance to zanamivir and it was found that:

• 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

Influenza vaccine coverage estimates for the 2022-2023 season are anticipated to be available in February or March 2023.

Vaccine Effectiveness

Influenza vaccine effectiveness estimates for the 2022-2023 season are anticipated to be available in February or March 2023.

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.