FluWatch report: December 13, 2020 to January 2, 2021 (weeks 51-53)

Influenza/Influenza-like Illness (ILI) Activity (geographic spread)

During week 53, no regions reported sporadic influenza activity. Other surveillance regions this week reported no influenza/ILI activity (Figure 1).

Influenza/ILI activity is lower at this point in the season compared to the previous four seasons; historically, between 47 and 53 regions reported activity at this point in the surveillance season.

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	No Activity
Que.	Montréal et Laval	No Activity
Que.	Ouest-du-Québec	No Activity
Que.	Montérégie	No Activity
Ont.	Central East	No Activity
Ont.	Central West	No Activity
Ont.	Eastern	No Activity
Ont.	North East	No Activity
Ont.	North West	No Activity
Ont.	South West	No Activity
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	Sporadic
Sask.	North	No Activity
Sask.	Central	No Activity
Sask.	South	No Activity
Alta.	North Zone	No Activity
Alta.	Edmonton	No Activity
Alta.	Central Zone	No Activity
Alta.	Calgary	No Activity
Alta.	South Zone	No Activity
B.C.	Interior	No Activity
B.C.	Fraser	No Activity
B.C.	Vancouver Coastal	No Activity
B.C.	Vancouver Island	No Activity
B.C.	Northern	No Activity
Y.T.	Yukon	No Activity
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 51-53, three laboratory detections of influenza were reported.

To date this season, 51 influenza detections have been reported (Figure 2), which is significantly lower than the past six seasons where an average of 8,784 influenza detections were reported for the season to date. All provinces and territories are closely monitoring indicators of influenza activity this season. Data in the FluWatch report represent surveillance data available at the time of writing, and may change as updates are received.

Twenty seven of the influenza detections reported to date this season are known to be associated with recent live attenuated influenza vaccine (LAIV) receipt and do not represent community circulation of seasonal influenza viruses. LAIV strains are attenuated but can be recovered by nasal swab in children and adults following vaccination with that product (i.e., "shedding"). For more information, please refer to the Canadian Immunization Guide Chapter on Influenza and Statement on Seasonal Influenza Vaccine for 2020–2021 (Section IV.2).

The percentage of laboratory tests positive for influenza remains at exceptionally low levels, despite elevated levels of testing this season. In weeks 51-53, 36,902 tests for influenza were performed at reporting laboratories; an average of 12,301 each week. Testing during this period was still higher compared to the past six seasons. The decline observed may be due to limited testing over the holiday weeks, or reduced testing given the low influenza activity to date (Figure 3a). The percentage of tests positive for influenza in weeks 51-53 was 0.01%, compared to 22.8% during the past six seasons (Figure 3b).

In Canada, at the national level, the influenza season typically starts around week 47 (mid-November) and is defined when at least 5% of influenza tests are positive and a minimum of 15 positive tests are observed nationally. Over the past 6 seasons, the influenza season has begun as early as week 43 (mid-October) and as late as week 1 (early January). As of week 53, influenza activity has remained below the threshold required to declare the start of the 2020-21 influenza season.

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 weeks or previous seasons.

For more detailed weekly and cumulative influenza data, see the text descriptions for Figure 2 or the Respiratory Virus Detections in Canada Report.

Number of laboratories reporting in week 53: 32 out of 35

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

Figure 2 - Text equivalent

Surveillance Week	A(Unsubtyped)	A(H3N2)	A(H1N1)	Influenza B	Percent Positive A	Percent Positive B
35	0	0	0	1	0.0	0.0
36	0	0	0	0	0.0	0.0
37	0	0	0	0	0.0	0.0
38	1	0	0	0	0.0	0.0
39	0	0	0	0	0.0	0.0
40	0	0	0	0	0.0	0.0
41	1	0	0	0	0.0	0.0
42	0	0	0	0	0.0	0.0
43	1	0	0	0	0.0	0.0
44	4	0	0	3	0.0	0.0
45	2	0	0	2	0.0	0.0
46	3	0	0	1	0.0	0.0
47	3	1	1	5	0.0	0.0
48	6	1	0	2	0.0	0.0
49	4	0	1	2	0.0	0.0
50	1	0	0	1	0.0	0.0
51	1	0	0	1	0.0	0.0
52	0	0	0	0	0.0	0.0
53	0	0	1	0	0.0	0.0

The shaded area represents the maximum and minimum number of influenza tests (a) or percentage of tests positive (b) reported by week from seasons 2014-2015 to 2019-2020.

Figure 3 - Text equivalent

a) Number of influenza tests, 2020-2021 compared to previous seasons

Surveillance Week	Number of Tests, 2020-21	Maximum Number of Tests	Minimum Number of Tests	Average Number of Tests
35	4962	1979	1311	1705
36	5176	2208	1323	1707
37	5308	2631	1778	2135
38	5996	3039	1987	2502
39	6670	3356	2365	2859
40	7093	4078	2443	3134
41	6783	4339	2673	3240
42	6730	4649	2648	3526
43	8188	4996	3084	3862
44	9585	4966	2994	4020
45	10706	5912	3117	4508
46	11918	5589	3176	4564
47	12971	6541	3587	5018
48	17810	7416	3569	5645
49	18436	8559	3836	6377
50	15894	9464	4017	7155
51	13682	11142	3487	8822
52	12101	11338	4272	9184
53	11119	13135	4821.5	10868
1	#N/A	14932	5371	12552
2	#N/A	16104	5315	13289
3	#N/A	15001	5270	11820
4	#N/A	15414	5873	11441
5	#N/A	16595	6739	11456
6	#N/A	16121	8324	11339
7	#N/A	14443	8074	10842
8	#N/A	14024	7606	10865
9	#N/A	14520	7507	10956
10	#N/A	17681	7005	11084
11	#N/A	12714	6435	9175
12	#N/A	10431	5976	8238
13	#N/A	9989	6063	7699
14	#N/A	8830	4773	7046
15	#N/A	7836	5090	6527
16	#N/A	6826	5000	5890
17	#N/A	6603	4440	5305
18	#N/A	5640	4143	4780
19	#N/A	5480	3680	4311
20	#N/A	5097	3046	3862
21	#N/A	4001	2577	3197
22	#N/A	3790	2424	2944
23	#N/A	3257	1969	2591
24	#N/A	3120	2034	2449
25	#N/A	2659	1731	2148
26	#N/A	2600	1573	1988
27	#N/A	2163	1554	1833
28	#N/A	2223	1451	1857
29	#N/A	2256	1436	1796
30	#N/A	1950	1463	1664
31	#N/A	2022	1386	1671
32	#N/A	1928	1269	1574
33	#N/A	2089	1251	1671
34	#N/A	2098	1374	1698

b) Percentage of tests positive for influenza, 2020-2021 compared to previous seasons

Surveillance Week	Percentage of tests positive, 2020-21	Maximum Percentage of Tests Positive	Minimum Percentage of Tests Positive	Average Percentage of Tests Positive
35	0.02	1.87	0.11	0.82
36	0.00	2.28	0.30	1.13
37	0.00	1.78	0.40	0.99
38	0.02	2.35	0.55	1.30
39	0.00	2.95	0.67	1.71
40	0.00	2.33	1.08	1.70
41	0.01	3.02	1.32	1.72
42	0.00	3.40	0.87	2.18
43	0.01	5.32	0.84	2.83
44	0.07	8.55	1.20	3.70
45	0.04	10.10	1.39	4.63
46	0.03	14.11	1.51	6.05
47	0.08	15.36	1.44	7.71
48	0.06	18.20	0.84	10.61
49	0.04	19.71	1.64	13.01
50	0.01	27.02	2.36	16.82
51	#N/A	29.09	3.30	20.11
52	#N/A	34.54	4.28	24.48
1	#N/A	31.66	5.85	23.41
2	#N/A	29.10	7.06	23.01
3	#N/A	30.07	12.24	23.63
4	#N/A	29.45	15.89	23.96
5	#N/A	30.62	19.60	24.90
6	#N/A	32.39	17.89	25.00
7	#N/A	32.51	16.28	25.05
8	#N/A	32.87	17.45	25.14
9	#N/A	34.28	16.80	24.59
10	#N/A	35.99	16.05	23.22
11	#N/A	31.41	16.19	21.41
12	#N/A	30.03	15.03	20.10
13	#N/A	28.25	14.50	19.56
14	#N/A	23.16	12.66	17.86
15	#N/A	20.73	11.95	16.27
16	#N/A	18.52	11.64	14.48
17	#N/A	17.30	9.76	12.83
18	#N/A	13.02	7.88	10.26
19	#N/A	11.95	4.96	8.98
20	#N/A	9.13	3.19	7.22
21	#N/A	7.45	2.97	5.60
22	#N/A	4.96	2.19	3.86
23	#N/A	4.39	0.87	2.86
24	#N/A	4.36	0.81	2.25
25	#N/A	3.95	0.63	1.88
26	#N/A	3.08	0.69	1.81
27	#N/A	2.83	0.42	1.48
28	#N/A	1.84	0.41	0.91
29	#N/A	1.55	0.47	1.09
30	#N/A	1.46	0.46	0.90
31	#N/A	1.93	0.58	1.11
32	#N/A	1.19	0.52	0.92
33	#N/A	1.69	0.40	0.85
34	#N/A	1.57	0.42	0.92
47	0.03	15.36	1.44	7.71

Syndromic / Influenza-like Illness Surveillance

Healthcare Professionals Sentinel Syndromic Surveillance

In weeks 51-53, an average of 0.7% of visits to healthcare professionals were due to influenza-like illness (ILI), which remains lower than average compared to recent seasons (Figure 4).

This trend should be interpreted with caution as there have been changes in healthcare seeking behavior of individuals and a smaller number of sentinels reporting in recent weeks compared to previous seasons.

Number of Sentinels Reporting in Week 53: 37

The shaded area represents the maximum and minimum percentage of visits for ILI reported by week from seasons 2014-2015 to 2019-2020

Figure 4 - Text equivalent

Surveillance Week	2020-2021	Average	Min	Max
35	0.1%	0.6%	0.4%	0.9%
36	0.2%	0.7%	0.4%	1.0%
37	0.4%	0.7%	0.6%	1.0%
38	0.3%	0.9%	0.5%	1.2%
39	0.4%	1.1%	0.8%	1.7%
40	0.2%	1.6%	0.8%	2.8%
41	0.4%	1.5%	0.9%	2.1%
42	0.5%	1.2%	0.8%	1.7%
43	0.3%	1.1%	0.7%	1.7%
44	0.3%	1.1%	0.9%	1.5%
45	0.4%	1.3%	0.7%	1.8%
46	0.8%	1.5%	1.1%	2.2%
47	0.3%	1.4%	1.1%	2.2%
48	0.5%	1.5%	0.9%	2.8%
49	0.5%	1.4%	1.0%	1.7%
50	0.4%	1.8%	1.4%	2.7%
51	0.5%	1.8%	1.0%	3.1%
52	0.5%	3.3%	1.9%	5.4%
53	0.7%	3.3%	1.9%	5.5%
1	#N/A	3.3%	1.8%	5.7%
2	#N/A	2.2%	1.3%	3.7%
3	#N/A	1.9%	1.1%	2.9%
4	#N/A	2.0%	1.4%	3.1%
5	#N/A	2.3%	1.4%	4.0%
6	#N/A	2.3%	0.9%	3.5%
7	#N/A	2.1%	0.8%	3.4%
8	#N/A	2.1%	0.9%	3.1%
9	#N/A	1.9%	1.0%	2.8%
10	#N/A	1.8%	1.1%	2.8%
11	#N/A	1.6%	0.6%	2.6%
12	#N/A	1.6%	1.1%	2.6%
13	#N/A	1.7%	1.1%	3.0%
14	#N/A	1.3%	0.9%	1.9%
15	#N/A	1.2%	0.8%	1.7%
16	#N/A	1.2%	0.7%	1.7%
17	#N/A	1.3%	0.5%	2.0%
18	#N/A	0.9%	0.6%	1.3%
19	#N/A	1.1%	0.6%	1.5%
20	#N/A	0.9%	0.5%	1.3%
21	#N/A	0.7%	0.3%	1.0%
22	#N/A	0.8%	0.6%	1.0%
23	#N/A	0.7%	0.6%	1.0%
24	#N/A	0.6%	0.4%	0.8%
25	#N/A	0.8%	0.5%	1.4%
26	#N/A	0.6%	0.5%	0.7%
27	#N/A	0.7%	0.5%	1.3%
28	#N/A	0.9%	0.6%	1.7%
29	#N/A	0.6%	0.2%	0.9%
30	#N/A	0.4%	0.2%	0.6%
31	#N/A	0.8%	0.3%	1.2%
32	#N/A	0.7%	0.4%	1.3%
33	#N/A	0.7%	0.4%	1.5%
34	#N/A	0.6%	0.4%	0.9%

FluWatchers

In week 53, 12,502 participants reported to FluWatchers and 15 participants (0.14%) reported symptoms of cough and fever (Figure 5). The percentage of participants reporting cough and fever remains at very low levels and may be a direct effect of individual and public health measures enacted to reduce the spread of COVID-19. FluWatchers reporting is not impacted by changes in health services or health seeking behaviours.

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

Number of Participants Reporting in Week 53: 12,502

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

Figure 5 - Text equivalent

Surveillance Week	2020-2021	Average	Min	Max
35	0.22%	N/A	N/A	N/A
36	0.21%	N/A	N/A	N/A
37	0.38%	N/A	N/A	N/A
38	0.29%	N/A	N/A	N/A
39	0.45%	N/A	N/A	N/A
40	0.49%	2.51%	2.18%	2.71%
41	0.44%	2.18%	1.81%	2.57%
42	0.33%	1.80%	1.61%	2.03%
43	0.17%	1.87%	1.49%	2.18%
44	0.26%	1.57%	1.39%	1.78%
45	0.29%	1.83%	1.42%	2.32%
46	0.28%	1.83%	1.22%	2.15%
47	0.31%	1.93%	1.44%	2.39%
48	0.26%	2.43%	1.67%	3.35%
49	0.17%	2.56%	1.97%	3.16%
50	0.15%	2.91%	2.12%	3.79%
51	0.22%	3.18%	2.53%	3.95%
52	0.10%	3.98%	2.81%	5.38%
53	0.12%	3.91%	2.83%	5.07%
1	0.00%	3.84%	2.85%	4.76%
2	0.00%	2.94%	1.90%	3.93%
3	0.00%	3.25%	2.35%	4.84%
4	0.00%	3.12%	2.13%	4.23%
5	0.00%	3.19%	2.62%	3.59%
6	0.00%	3.47%	2.76%	4.28%
7	0.00%	3.18%	2.58%	3.79%
8	0.00%	3.09%	2.54%	3.65%
9	0.00%	2.81%	2.38%	3.53%
10	0.00%	2.58%	2.12%	3.11%
11	0.00%	2.33%	1.89%	2.63%
12	0.00%	2.60%	2.46%	2.82%
13	0.00%	2.48%	1.99%	3.06%
14	0.00%	2.13%	1.35%	2.58%
15	0.00%	1.78%	1.60%	1.93%
16	0.00%	2.00%	1.47%	2.44%
17	0.00%	1.73%	1.40%	2.31%
18	0.00%	1.50%	1.19%	2.09%
19	0.00%	N/A	N/A	N/A
20	0.00%	N/A	N/A	N/A
21	0.00%	N/A	N/A	N/A
22	0.00%	N/A	N/A	N/A
23	0.00%	N/A	N/A	N/A
24	0.00%	N/A	N/A	N/A
25	0.00%	N/A	N/A	N/A
26	0.00%	N/A	N/A	N/A
27	0.00%	N/A	N/A	N/A
28	0.00%	N/A	N/A	N/A
29	0.00%	N/A	N/A	N/A
30	0.00%	N/A	N/A	N/A
31	0.00%	N/A	N/A	N/A
32	0.00%	N/A	N/A	N/A
33	0.00%	N/A	N/A	N/A
34	0.00%	N/A	N/A	N/A

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Influenza Outbreak Surveillance

In weeks 51-53, no influenza-like-illness (ILI) or laboratory-confirmed outbreaks were reported.

To date this season, 92 influenza-like-illness (ILI) outbreaks in schools and/or daycares, and no other influenza or ILI outbreaks have been reported in any other settings.

Outbreaks of ILI in schools and daycares are identified when greater than 10% absenteeism due to ILI are reported in these settings. The number of ILI outbreaks in schools and daycares reported is higher compared to the same time period in the previous two seasons. This is not unexpected given changes to outbreak surveillance, specifically increased vigilance in schools to monitor and report absenteeism due to ILI, and the increased restrictions on attendance for children with symptoms of viral respiratory illness.

Outbreaks of ILI are not specific to any one respiratory pathogen and can be due influenza or other respiratory viruses, including rhinovirus and SARS-CoV-2, the virus that causes COVID-19. Rhinovirus commonly circulates during the fall and can cause clusters of cases with respiratory illness that could be captured as ILI. For more information on the respiratory viruses currently circulating in Canada, please refer to the Respiratory Virus Detections in Canada Report.

Number of provinces and territories reporting in weeks 51-53^{Footnote 1}: 13 out of 13

Severe Outcomes Influenza Surveillance

Provincial/Territorial Influenza Hospitalizations and Deaths

In weeks 51-53, no influenza-associated hospitalizations were reported by participating provinces and territories^{Footnote 2}. To date no influenza-associated hospitalizations were reported by participating provinces and territories.

Number of provinces and territories reporting in week 51-53: 9 out of 9

Pediatric Influenza Hospitalizations and Deaths

In weeks 51-53, no influenza-associated hospitalizations were reported. To date this season, less than five pediatric (≤16 years of age) hospitalizations with influenza have been reported by the Immunization Monitoring Program Active (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 2020-21 season.

Influenza Strain Characterizations

Due to the very low influenza circulation to date this season, the National Microbiology Laboratory has not yet received influenza viruses collected during the 2020-21 season for strain characterization.

Antiviral Resistance

Due to the very low influenza circulation to date this season, the National Microbiology Laboratory has not yet received influenza viruses collected during the 2020-21 season for antiviral resistance testing.

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 2020-21 season are anticipated to be available in March 2021.

Vaccine Effectiveness

Influenza vaccine effectiveness estimates are typically available in February or March of each year; this will be delayed or not possible to estimate for the 2020-21 season if low influenza circulation continues.

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.