FluWatch report: November 27 to December 3, 2022 (week 48)

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 48, almost all regions in Canada reported influenza activity with five regions in three provinces (P.E.I., Man. and Alta.) reporting widespread activity (Figure 1).

Number of Regions Reporting in Week 48: 53 out of 53

Figure 1 - Text description

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

Laboratory-Confirmed Influenza Detections

In week 48, a total of 9,855 laboratory detections (9,842 influenza A and 13 influenza B) were reported.

The following results were reported from sentinel laboratories across Canada in week 48 (Figures 2 and 3):

• The weekly percentage of tests positive for influenza remains above expected pre-pandemic levels at 23.8% in week 48, but remained similar to the previous week (23.9% in week 47) after many weeks of steep increase.
• Among subtyped influenza A detections, 97% (2,132) were influenza A(H3N2) and 3% (67) were influenza A(H1N1).
• Among detections for which age information was reported (6,007), 2,454 (41%) of detections were in individuals aged 0-19 years old. The proportion of detections among individuals aged 0-19 years old has been slowly decreasing, whereas the proportion among adults, particularly seniors aged 65+ (26%) has been increasing in recent weeks.

To date this season (August 28, 2022 to December 3, 2022):

• 34,413 influenza detections were reported, of which 99% (34,312) were influenza A and among subtyped influenza A detections (13,208), influenza A(H3N2) accounted for 96% of detections.
• 20,986 laboratory-confirmed influenza detections with age information were reported, of which 9,993 (48%) 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 48: 33 out of 35

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	35	20	3	0.5	0.0
39	44	53	22	5	0.7	0.0
40	63	66	16	4	1.0	0.0
41	120	110	20	1	1.4	0.0
42	217	204	11	9	2.4	0.1
43	417	595	23	6	5.6	0.0
44	1034	1351	54	7	10.9	0.0
45	1897	2268	69	11	16.0	0.0
46	3210	2963	97	16	19.8	0.1
47	5531	2851	151	16	23.9	0.0
48	6893	2132	67	13	23.8	0.0

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	10.9	0.2	0.1	8.5	1.2	3.7
45	16.0	0.1	0.0	10.1	1.4	4.6
46	19.9	0.2	0.0	14.1	1.5	6.1
47	23.9	0.2	0.1	15.4	1.4	7.7
48	23.8	0.3	0.1	18.2	0.8	10.6
49	-	0.3	0.0	19.7	1.6	13.0
50	-	0.3	0.0	27.0	2.4	16.8
51	-	0.2	0.0	29.1	3.3	20.1
52	-	0.1	0.0	34.5	4.3	24.5
1	-	0.1	0.0	31.7	5.8	23.4
2	-	0.1	0.0	29.1	7.1	23.0
3	-	0.1	0.0	30.1	12.2	23.6
4	-	0.1	0.0	29.5	15.9	24.0
5	-	0.0	0.0	30.6	19.6	24.9
6	-	0.1	0.0	32.4	17.9	25.0
7	-	0.0	0.0	32.5	16.3	25.1
8	-	0.1	0.0	32.9	17.5	25.1
9	-	0.1	0.0	34.3	16.8	24.6
10	-	0.2	0.0	36.0	16.0	23.2
11	-	0.3	0.0	31.4	16.2	21.4
12	-	0.9	0.0	30.0	15.0	20.1
13	-	1.5	0.0	28.3	14.5	19.6
14	-	2.5	0.0	23.2	12.7	17.9
15	-	3.9	0.0	20.7	11.9	16.3
16	-	7.0	0.0	18.5	11.6	14.5
17	-	9.7	0.0	17.3	9.8	12.8
18	-	11.3	0.0	13.0	7.9	10.3
19	-	12.6	0.0	11.9	5.0	9.0
20	-	10.4	0.0	9.1	3.2	7.2
21	-	9.8	0.0	7.4	3.0	5.6
22	-	8.4	0.0	5.0	2.2	3.9
23	-	7.0	0.0	4.4	0.9	2.9
24	-	5.0	0.0	4.4	0.8	2.2
25	-	3.0	0.0	3.9	0.6	1.9
26	-	2.3	0.0	3.1	0.7	1.8
27	-	1.2	0.0	2.8	0.4	1.5
28	-	0.8	0.0	1.8	0.4	0.9
29	-	0.7	0.0	1.6	0.5	1.1
30	-	0.4	0.0	1.5	0.5	0.9
31	-	0.3	0.0	1.9	0.6	1.1
32	-	0.2	0.0	1.2	0.5	0.9
33	-	0.2	0.0	1.7	0.4	0.9
34	-	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	99.7%	0.3%	3805
5 to 19	99.8%	0.2%	6188
20 to 44	99.6%	0.4%	4046
45 to 64	99.8%	0.2%	2358
65+	99.7%	0.3%	4589

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	2.9%	97.1%	2012
5 to 19	2.8%	97.2%	2919
20 to 44	4.8%	95.2%	1927
45 to 64	7.7%	92.3%	1087
65+	4.8%	95.2%	2132

Syndromic / Influenza-like Illness Surveillance

Healthcare Practitioners Sentinel Surveillance

In week 48, 3.7% of visits to healthcare professionals were due to influenza-like illness (ILI) (Figure 5). The percentage of visits for ILI is above expected levels for this time of year.

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 makes the percentage of visits for ILI an important indicator of overall respiratory illness morbidity in the community in the presence of co-circulating viruses.

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 48: 38

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	2.2%	1.0%	0.4%	1.2%	0.9%	1.5%
46	2.3%	0.9%	0.8%	1.4%	1.2%	1.8%
47	3.6%	0.7%	0.3%	1.6%	1.1%	2.2%
48	3.7%	1.1%	0.5%	1.5%	1.1%	2.2%
49	-	0.9%	0.5%	1.7%	1.0%	2.8%
50	-	1.1%	0.4%	1.5%	1.1%	1.7%
51	-	1.7%	0.5%	1.9%	1.4%	2.7%
52	-	1.5%	0.5%	2.0%	1.0%	3.1%
1	-	2.1%	0.7%	3.4%	1.9%	5.4%
2	-	1.6%	0.4%	3.4%	1.8%	5.7%
3	-	1.4%	0.2%	2.3%	1.3%	3.7%
4	-	0.9%	0.3%	2.0%	1.1%	2.9%
5	-	1.0%	0.2%	2.1%	1.4%	3.1%
6	-	0.7%	0.5%	2.4%	1.4%	4.0%
7	-	0.7%	0.3%	2.4%	0.9%	3.5%
8	-	0.8%	0.2%	2.3%	0.8%	3.4%
9	-	0.7%	0.2%	2.3%	0.9%	3.1%
10	-	0.9%	0.2%	2.0%	1.0%	2.8%
11	-	0.6%	0.2%	1.9%	1.1%	2.8%
12	-	0.8%	0.3%	1.6%	0.6%	2.6%
13	-	1.2%	0.4%	1.6%	1.1%	2.6%
14	-	1.1%	0.2%	1.7%	1.1%	3.0%
15	-	1.2%	0.3%	1.3%	0.9%	1.9%
16	-	1.5%	0.3%	1.2%	0.8%	1.7%
17	-	1.3%	0.4%	1.2%	0.7%	1.7%
18	-	1.8%	0.5%	1.3%	0.5%	2.0%
19	-	1.7%	0.3%	0.9%	0.6%	1.3%
20	-	1.5%	0.5%	1.1%	0.6%	1.5%
21	-	1.4%	0.3%	0.9%	0.5%	1.3%
22	-	1.0%	0.3%	0.7%	0.3%	1.0%
23	-	1.1%	0.2%	0.8%	0.6%	1.0%
24	-	1.3%	0.2%	0.7%	0.6%	1.0%
25	-	1.0%	0.2%	0.6%	0.4%	0.8%
26	-	0.8%	0.2%	0.8%	0.5%	1.4%
27	-	1.7%	0.3%	0.6%	0.5%	0.7%
28	-	1.0%	0.1%	0.7%	0.5%	1.3%
29	-	0.9%	0.3%	0.9%	0.6%	1.7%
30	-	1.3%	0.2%	0.6%	0.2%	0.9%
31	-	0.9%	0.2%	0.4%	0.2%	0.6%
32	-	0.9%	0.2%	0.8%	0.3%	1.2%
33	-	0.8%	0.3%	0.7%	0.4%	1.3%
34	-	1.0%	0.5%	0.7%	0.4%	1.5%

FluWatchers

In week 48, 10,909 participants reported to FluWatchers, of which 3.1% reported symptoms of cough and fever (Figure 6). The percentage of FluWatchers who have reported cough and fever is above the seasonal average.

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. This makes the proportion of individuals reporting cough and fever an important indicator of overall respiratory illness activity in the community in the presence of co-circulating viruses.

FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

Among the 338 participants who reported cough and fever:

• 21% consulted a healthcare professional;
• 85% reported days missed from work or school, resulting in an average of 3.1 missed days from work or school among those 288 participants.

The Northwest Territories had the highest participation rate this week (51 participants per 100,000 population) and the neighbourhood with postal code, K0A had the highest number of participants (152). 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 48: 10,909

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	3.0%	0.5%	0.3%	1.8%	1.4%	2.3%
46	2.9%	0.4%	0.3%	1.8%	1.2%	2.2%
47	3.1%	0.6%	0.3%	1.9%	1.4%	2.4%
48	3.1%	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 48, 66 laboratory-confirmed influenza outbreaks were reported in Canada (36 in long-term care facilities (LTC), 17 in facilities categorized as ‘other', and 13 in acute care facilities). All outbreaks were due to influenza A. 68 ILI outbreaks were reported in schools/daycares.

To date this season (August 28, 2022 to December 3, 2022):

• 292 laboratory-confirmed influenza outbreaks have been reported
  • 144 were in LTC facilities (49%)
  • 80 were in facilities categorized as ‘other' (27%)
  • 57 were in acute care facilities (20%)
  • 4 were in schools/daycares (1%)
  • All but one outbreak was due to influenza A
• 185 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 48: 13 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	1	0	0	0	0
39	0	2	1	0	0
40	0	2	3	0	0
41	1	2	1	0	0
42	3	1	2	0	0
43	1	8	6	3	0
44	1	10	12	1	0
45	12	15	7	0	0
46	12	35	17	0	0
47	13	32	13	0	7
48	13	36	17	0	0

Influenza Severe Outcomes Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In week 48, 212 influenza-associated hospitalizations and 31 ICU admissions were reported by participating provinces and territories^{Footnote 2}. This week, 6 influenza-associated deaths were reported.

To date this season 1,670 influenza-associated hospitalizations were reported (August 28, 2022 to December 3, 2022) by participating provinces and territories:

• >99% of the hospitalizations were associated with influenza A.
• Of the cases with subtype information (1074), 94% were associated with influenza A(H3N2)
• The highest cumulative hospitalization rates up to week 48 were among children under 5 years of age (56/100,000 population) and adults 65 years of age and older (49/100,000 population).

To date this season (August 28, 2022 to December 3, 2022), 160 ICU admissions and 54 influenza-associated deaths were reported.

Number of provinces and territories reporting in week 48: 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	0.7	0.2
40	0.2	-	0.1	0.2	0.7	0.2
41	0.2	0.1	0.1	0.2	1.2	0.3
42	0.7	0.1	0.3	0.4	1.5	0.5
43	2.5	1.1	0.5	0.9	2.7	1.2
44	8.5	3.1	1.0	1.9	5.6	2.8
45	19.5	6.2	2.2	4.4	15.0	6.6
46	34.7	9.4	4.1	6.7	27.6	11.3
47	51.4	14.2	6.4	10.7	42.3	17.4
48	56.4	15.1	7.6	12.7	49.3	19.9

Pediatric Influenza Hospitalizations and Deaths

In week 48, 247 influenza-associated pediatric (≤16 years of age) hospitalizations and 34 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 above levels typically seen at the peak of the influenza season (Figure 9). All hospitalisations reported in week 48 were associated with influenza A. This week, less than 5 influenza-associated pediatric deaths were reported.

To date this season (August 28, 2022 to December 3, 2022), 959 pediatric influenza-associated hospitalizations, 131 ICU admissions and 5 influenza-associated pediatric deaths have been reported. Children aged between 2-4 years and 5-9 years account for more than 55% of the reported pediatric hospitalizations (Figure 10).

Figure 9 - Text description

Surveillance week	2022-2023	2021-2022	Average	Min	Max
35	1	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	41	0	4	1	11
44	79	0	6	1	21
45	152	0	9	2	36
46	196	0	12	1	37
47	228	1	11	1	35
48	247	1	20	2	46
49	#N/A	1	21	3	41
50	#N/A	0	31	4	54
51	#N/A	2	44	5	82
52	#N/A	1	63	14	103
1	#N/A	1	62	21	107
2	#N/A	0	50	12	100
3	#N/A	0	51	27	80
4	#N/A	0	58	34	90
5	#N/A	0	59	25	120
6	#N/A	0	60	15	115
7	#N/A	0	59	17	118
8	#N/A	1	65	25	134
9	#N/A	1	57	12	151
10	#N/A	0	54	17	135
11	#N/A	0	51	16	118
12	#N/A	0	39	13	87
13	#N/A	8	32	15	66
14	#N/A	7	28	12	56
15	#N/A	18	25	11	56
16	#N/A	19	23	11	41
17	#N/A	23	19	9	37
18	#N/A	48	16	8	28
19	#N/A	36	11	5	19
20	#N/A	29	10	0	18
21	#N/A	32	6	4	9
22	#N/A	14	6	1	9
23	#N/A	16	3	1	7
24	#N/A	12	3	1	6
25	#N/A	9	2	0	5
26	#N/A	6	1	0	3
27	#N/A	3	1	0	2
28	#N/A	7	1	0	2
29	#N/A	2	1	0	3
30	#N/A	3	1	0	1
31	#N/A	1	0	0	0
32	#N/A	0	0	0	0
33	#N/A	1	0	0	2
34	#N/A	0	1	0	2

Figure 10 - Text description

Age Group	Total
0-5 mo	94
6-23 mo	154
2-4 yr	286
5-9 yr	251
10-16 yr	174

Influenza Strain Characterization

Since September 1, 2022, the National Microbiology Laboratory (NML) has characterized 79 influenza viruses (72 A(H3N2), 7 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)

• 71 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 71 influenza A (H3N2) viruses characterized, 50 belonged to genetic group 3C.2a1b.2a2. Sequences are pending for the remaining viruses.

Influenza A(H1N1)

• 7 influenza A (H1N1) viruses were 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

70 influenza viruses (63 A(H3N2) and 7 A(H1N1)) were tested for resistance to oseltamivir and it was found that:

• All influenza viruses were sensitive to oseltamivir.

Zanamivir

70 influenza viruses (63 A(H3N2) and 7 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.