Seasonal Influenza in Alberta

Influenza data included in the interactive data application are aggregated by week and up-to-date as of end of week 29 (July 22, 2023), unless stated otherwise.

View Alberta COVID-19 statistics

Highlights

Note: aggregate data in highlights are cumulative for the entire 2022-2023 season

9,731
cases 📈

9,025
influenza A 📈

706
influenza B 📈

2,236
hospitalizations 🚑

235
ICU admissions 🏥

121
deaths ⚱

Influenza A (H3N2)
dominant subtype

Summary

Table 1: Summary of laboratory-confirmed seasonal influenza in Alberta, 2022-2023

	Cases (n)	Influenza A cases (n)	Influenza B cases (n)	Hospitalizations (n)	ICU admissions (n)	Deaths (n)
Alberta	9,731	9,025	706	2,236	235	121
Calgary Zone	3,311	3,050	261	850	94	32
Central Zone	1,134	1,080	54	255	26	23
Edmonton Zone	2,871	2,616	255	638	65	31
North Zone	1,685	1,599	86	269	27	16
South Zone	721	671	50	216	23	19
Unknown	9	9	0	8	0	0

Figure 1: Laboratory-confirmed influenza cases by subtype

Figure 2: Laboratory-confirmed influenza cases by subtype from the previous five seasons

Figure 3: Laboratory-confirmed seasonal influenza cases in Alberta since the 2009-2010 season

Geospatial

Figure 4: Laboratory-confirmed seasonal influenza cases in the previous 5 seasons by zone

Characteristics

Figure 5: Cases and rates (per 100,000 population) of laboratory-confirmed influenza by age group, 2022-2023

Severe Outcomes

Figure 6: Cumulative hospitalizations, ICU admissions and deaths among people with laboratory-confirmed influenza cases by age group, 2022-2023

Table 2: Cumulative count and rate (per 100,000 population) of hospitalizations, ICU admissions and deaths among laboratory-confirmed influenza cases by age group, 2022-2023

Age group	Hospitalizations		ICU admissions		Deaths
	Count	Population rate	Count	Population rate	Count	Population rate
Under 1 year	99	197.8	14	28.0	0	0.0
1-4 years	273	131.6	30	14.5	1	0.5
5-9 years	157	55.2	10	3.5	1	0.4
10-19 years	87	15.7	11	2.0	1	0.2
20-29 years	78	13.2	10	1.7	0	0.0
30-39 years	138	19.1	20	2.8	4	0.6
40-49 years	111	17.4	19	3.0	5	0.8
50-59 years	147	26.8	28	5.1	10	1.8
60-69 years	373	73.6	54	10.7	25	4.9
70-79 years	400	137.6	30	10.3	32	11.0
80-89 years	282	235.2	8	6.7	27	22.5
90+ years	91	321.1	1	3.5	15	52.9
Unknown	0	0.0	0	0.0	0	0.0

Laboratory Testing

Table 3: Summary of influenza viruses, 2022-2023

Respiratory virus	Number of tests in the current week (n)	Cumulative number of tests in the season (n)	Percent positivity in the current week (%)	Rolling percent positivity (%; previous 3 weeks)
Influenza A	2,028	163,552	0.4	0.7
Influenza B	2,029	163,224	0.0	0.1

Figure 7: Influenza tests and positivity by week

Outbreaks

Table 4: Influenza outbreaks by outbreak setting, 2022-2023

Influenza	Acute Care Facility	Long Term Care Facility	Other	Supportive Living/Home Living Sites	Total
COVID-19 and Influenza A (H1N1)	0	2	0	2	4
COVID-19 and Influenza A (H3N2)	2	7	0	20	29
COVID-19 and Influenza A (Untyped)	0	0	1	4	5
COVID-19 and Influenza B	0	0	0	0	0
Influenza A (H1N1)	1	2	0	1	4
Influenza A (H3N2)	9	12	0	25	46
Influenza A (Untyped)	2	5	1	3	11
Influenza B	0	0	1	0	1
Influenza Mixed	0	0	0	0	0
Total	14	28	3	55	100

Table 5: Influenza outbreaks by zone, 2022-2023

Respiratory virus	Calgary Zone	Central Zone	Edmonton Zone	North Zone	South Zone	Total
COVID-19 and Influenza A (H1N1)	3	1	0	0	0	4
COVID-19 and Influenza A (H3N2)	10	7	8	0	4	29
COVID-19 and Influenza A (Untyped)	1	3	0	1	0	5
COVID-19 and Influenza B	0	0	0	0	0	0
Influenza A (H1N1)	1	1	1	1	0	4
Influenza A (H3N2)	11	14	13	6	2	46
Influenza A (Untyped)	6	4	1	0	0	11
Influenza B	0	1	0	0	0	1
Influenza Mixed	0	0	0	0	0	0
Total	32	31	23	8	6	100

Immunizations

Data Notes

More information

Seasonal influenza in Alberta Annual Report

Alberta Health Services Respiratory Virus Surveillance

Data sources

Communicable Disease Reporting System (CDRS), Alberta Health Provincial Surveillance Information (PSI), Alberta Health Alberta Health Care Insurance Plan (AHCIP) Quarterly Population Registry, Alberta Health Immunization/Adverse Reactions to Immunization (Imm/ARI), Alberta Health

Definitions

Influenza Deaths

A death resulting from a clinically compatible illness in a laboratory-confirmed influenza case, unless there is a clear alternative cause of death identified (e.g. trauma, poisoning, drug overdos, etc.).

A Medical Officer of Health or relevant public health authority may use their discretion when determining if a death was due to influenza, and their judgement will supersede the above criteria.

A death due to influenza may be attributed when influenza is the cause of death or is a contributing factor.

Influenza Outbreaks

Influenza outbreaks that occur in group settings such as hospitals, residential institutions, schools, and child care facilities are reported to Alberta Health. Outbreaks are defined as the occurrence of a communicable disease in a community, region, or setting where the number of cases is more than would be expected for a defined period of time. Influenza outbreaks in hospitals, residential institutions, and other closed communities are defined as two or more cases of influenza-like illness, with at least one laboratory-confirmed case. School influenza outbreaks require greater than 10 per cent absenteeism or absenteeism that is 10 per cent higher than baseline levels. Please see the Public Health Disease Management Guidelines: Influenza, Seasonal and Public Health Disease Management Guidelines: Epidemics for more information.

Lab Positivity

Influenza percent positivity in Alberta is calculated using the Test Over Test method, which is the same method employed by the US Centers for Disease Control and Prevention. The calculation is as follows:

Daily Number of Positive Tests / (Daily Number of Positive Tests + Daily Number of Negative Tests) Q/RT-PCR tests are the only COVID-19 tests included in this calculation.

Vaccine coverage

Individuals who received one dose was calculated as (# of individuals who received at least one dose) / (population estimate).

Immunizations

*‘Other Providers’ include Alberta Health Services (AHS) non-Public Health, non-AHS (including Long-term care (LTC) sites) and Physicians from AHS, IDSM, and First Nations and Inuit Health Branch (FNIHB). Includes influenza immunization doses administration data from AHS (AHS non-Public Health, non-AHS (including LTC sites) and Physicians), AH (IDSM, WHS and Covenant OHS) and FNIHB for the month of Oct, Nov, Dec, Jan, Feb, Mar 2021/22.

Disclaimer

The content and format of this report are subject to change. Cases are under investigation and numbers may fluctuate as cases are resolved.