FluWatch report: August 14 to August 27, 2016 (weeks 33-34)
- Overall, influenza activity is at interseasonal levels with all regions of Canada reporting low to no influenza activity.
- Twenty-three positive influenza tests (less than 1% positive) were reported in weeks 33-34, most influenza A(H3N2).
- No influenza outbreaks have been reported since week 22 (beginning of June).
- Three hospitalizations were reported in weeks 33-34.
- This is the last FluWatch report of the 2015-16 season. FluWatch will begin reporting for the 2016-2017 season on September 16, 2016 and weekly reporting will resume on week 40.
- For more information on the flu, see our Flu(influenza) web page.
If you are a primary health care practitioner (General Practitioner, Nurse Practitioner or Registered Nurse) interested in becoming a FluWatch sentinel for the 2016-17 influenza season, please contact us at FluWatch@phac-aspc.gc.ca
On this page
- Influenza/ILI Activity (geographic spread)
- Laboratory Confirmed Influenza Detections
- Influenza-like Illness Consultation Rate
- Pharmacy Surveillance
- Influenza Outbreak Surveillance
- Sentinel Pediatric Hospital Influenza Surveillance
- Provincial/Territorial Influenza Hospitalizations and Deaths
- Influenza Strain Characterizations
- Antiviral Resistance
- International Influenza Reports
- FluWatch definitions for the 2015-2016 season
Influenza/Influenza-like Illness Activity (geographic spread)
In week 34, the majority of regions (36) in Canada reported no influenza activity. Sporadic activity was reported in a total seven regions across three provinces (BC, AB and ON). A total of ten regions reported no data on week 34.
Laboratory Confirmed Influenza Detections
In weeks 33-34, the percentage of tests positive for influenza remained at interseasonal levels, ranging from 0.7% in week 33 to 0.9% in week 34.
Nationally in weeks 33-34, there were 23 positive influenza tests reported. Influenza A accounted for the majority of influenza detections, representing 91% of detections in weeks 33-34. Overall in week 34, laboratory detections of influenza were low across Canada. Seven regions (SK, MB, NS, PE, NL, YT, and NU) reported no influenza detections. To date, 72% of influenza detections have been influenza A and among those subtyped, the vast majority have been influenza A(H1N1) [90% (11081/12249)].
Figure 3. Cumulative numbers of positive influenza specimens by type/subtype and province, Canada, 2015-16
Note: Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks.
To date this season, detailed information on age and type/subtype has been received for 33,559 cases. Children and teenagers (0-19yrs) accounted for 48% of influenza B cases and one third of all influenza cases. Children and teenagers (0-19yrs), young adults (20-44yrs) and middle-aged adults (45-64yrs) accounted for approximately an equal proportion of influenza A(H1N1) cases. Weekly numbers are not reported due to small numbers.
|Age groups (years)||Weeks 33-34 ( August 14 to August 27, 2016)||Cumulative (August 30, 2015 to August 27, 2016)|
|Influenza A||B||Influenza A||B||Influenza A and B|
|A Total||A(H1) pdm09||A(H3)||A UnSTable 1 - Footnote 3||Total||A Total||A(H1) pdm09||A(H3)||A UnSTable 1 - Footnote 3||Total||#||%|
|<5||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||4544||1720||77||2747||1774||6318||19%|
|5-19||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||2420||1029||104||1287||2711||5131||15%|
|20-44||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||5839||2772||168||2899||2209||8048||24%|
|45-64||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||6434||2813||212||3409||1112||7546||22%|
|65+||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||4904||1634||457||2813||1612||6512||19%|
|Total||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||24141||9968||1018||13155||9418||33559||100%|
|PercentageTable 1 - Footnote 2||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||Table 1 - Footnote x||72%||41%||4%||54%||28%|
For data on other respiratory virus detections see the Respiratory Virus Detections in Canada Report on the Public Health Agency of Canada website.
Influenza-like Illness Consultation Rate
The national ILI consultation rate remained low in weeks 33 and 34 compared to previous weeks (9.1 per 1,000 patient visits in week 33, and 6.9 per 1,000 patient visits in week 34). In week 34, the highest ILI consultation rate was found in the 65+ years age group (14.1 per 1,000) and the lowest was found in the 0 to 4 years age group where no ILI cases were reported (Figure 4).
In week 33, the proportion of prescriptions for antivirals remained low. The proportions ranged from 1.9 antiviral prescriptions per 100,000 total prescriptions in week 33 to 2.3 prescriptions per 100,000 total prescriptions in week 34. The rates in weeks 33-34 were lower than their five year historical averages.
Influenza Outbreak Surveillance
In weeks 23-34, no new laboratory confirmed influenza outbreaks were reported. No outbreaks have been reported since week 23 of the current season.
To date this season, 428 outbreaks have been reported. By week 34 in the 2014-15 season, 1,734 outbreaks had been reported, and in the 2013-14 season, 271 outbreaks had been reported.
Figure 6. Overall number of new laboratory-confirmed influenza outbreaksFigure 5 - Footnote 1 by report week, Canada, 2015-2016
Sentinel Pediatric Hospital Influenza Surveillance
Paediatric Influenza Hospitalizations and Deaths
In weeks 33-34, no laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations, ICU admissions or deaths were reported by the Immunization Monitoring Program Active (IMPACT) network (Figure 7).
A total of 227 intensive care unit (ICU) admissions have been reported this season. Children aged 2 to 9 years accounted for 54% of ICU admissions. A total of 157 ICU cases (68%) reported at least one underlying condition or comorbidity. Eight influenza-associated deaths have been reported.
To date this season, 1,363 hospitalizations have been reported by the IMPACT network: 903 cases (66%) were due to influenza A and 460 cases (34%) were due to influenza B. This season’s count of pediatric hospitalizations is nearly double that reported up to week 34 in the 2014-15 season (N=714). The current year total number of cases also exceeds the total number of cases reported in the past five seasons.
|Age Groups||Cumulative (30 Aug. 2015 to 27 Aug. 2016)|
|Influenza A||Influenza B||Influenza A and B|
|A Total||A(H1) pdm09||A(H3)||A (UnS)||B Total|
Figure 7 - Text Description
Adult Influenza Hospitalizations and Deaths
Sentinel surveillance for the 2015-2016 influenza season ended on April 30th, 2016 (week 20).
For the 2015-16 season, 1,153 hospitalizations have been reported by CIRN-SOS (Table 3). The majority of hospitalized cases were due to influenza A (81%) and the largest reported proportion was among adults ≥65 years of age (50%). One hundred and ninety-one intensive care unit (ICU) admissions have been reported of which 132 admissions reported at least one underlying condition or comorbidity. A total of 55 deaths have been reported this season with the majority of deaths reported in adults ≥65 years of age (62%).
|Age groups (years)||Cumulative (Nov. 1, 2015 to Apr. 30, 2016)|
|Influenza A||B||Influenza A and B|
|A Total||A(H1) pdm09||A(H3)||A(UnS)||Total||# (%)|
Figure 8. Percentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group (≥16 year of age), Canada 2015-16Figure 8 - Footnote *
Provincial/Territorial Influenza Hospitalizations and Deaths
Since the start of the 2015-16 season, 5,365 laboratory-confirmed influenza-associated hospitalizations have been reported. A total of 4,169 hospitalizations (78%) were due to influenza A and 1,196 (22%) were due to influenza B. Of the 541 ICU admissions reported, 478 (88%) were due to influenza A. A total of 270 deaths have been reported; all but 42 were associated with influenza A.
Overall this season, the greatest proportion of hospitalizations have been reported among adults ≥65 years of age. The largest proportion of ICU admissions was reported in adults 45-64years of age and the highest proportion of fatal cases was reported in adults ≥65 years of age (Figure 9). Pediatric (0-19 years) accounted for 29% of all hospitalizations and 5% of all deaths reported to date this season. Similar to findings from the IMPACT network, there have been more pediatric hospitalizations reported to date compared to the year-end totals in each of the previous four influenza seasons.
Figure 9. Percentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada 2015-16
See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2011-12 to 2015-16 on the Public Health Agency of Canada website.
Influenza Strain Characterizations
The NML receives a proportion of the influenza positive specimens from provincial laboratories for strain characterization and antiviral resistance testing. Characterization data reflect the results HI testing compared to the reference influenza strains recommended by WHO.
During the 2015-16 influenza season, the National Microbiology Laboratory (NML) has characterized 3,040 influenza viruses [288 A(H3N2), 1,491 A(H1N1) and 1,261 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assays, 91 A(H3N2) viruses were antigenically characterized as A/Switzerland/9715293/2013-like using antiserum raised against cell-propagated A/Switzerland/9715293/2013.
Sequence analysis was done on 170 A(H3N2) viruses. All viruses belonged to a genetic group for which most viruses were antigenically related to A/Switzerland/9715293/2013. A/Switzerland/9715293/2013 is the A(H3N2) component of the 2015-16 Northern Hemisphere's vaccine.
Influenza A (H1N1): All of the 1,491 A(H1N1) viruses characterized were antigenically similar to A/California/7/2009, the A(H1N1) component of the 2015-16 influenza vaccine.
Influenza B: A total of 267 influenza B viruses characterized were antigenically similar to the vaccine strain B/Phuket/3073/2013. A total of 994 influenza B viruses were characterized as B/Brisbane/60/2008-like, one of the influenza B components of the 2015-16 Northern Hemisphere quadrivalent influenza vaccine.
During the 2015-16 season, the National Microbiology Laboratory (NML) has tested 2,243 influenza viruses for resistance to oseltamivir, 2,257 influenza viruses for resistance to zanamivir and 1,805 influenza viruses for resistance to amantadine. All but 10 tested viruses were sensitive to oseltamivir. The 10 H1N1 viruses resistant to oseltamivir had a H275Y mutation. All viruses tested for resistance were sensitive to zanamivir. All but two influenza A viruses were resistant to amantadine (Table 4).
|Virus type and subtype||Oseltamivir||Zanamivir||Amantadine|
|# tested||# resistant (%)||# tested||# resistant (%)||# tested||# resistant (%)|
|A (H3N2)||218||0 (0%)||219||0 (0%)||292||252 (99.7%)|
|A (H1N1)||1154||10 (0.9%)||1167||0 (0%)||1512||1511 (99.9%)|
|B||871||(0%)||871||0 (0%)||NATable 4 - Footnote *||NATable 4 - Footnote *|
|Total||2243||10 (0.4%)||2257||0 (0%)||1805||1803 (99.9%)|
International Influenza Reports
- World Health Organization influenza update
- World Health Organization FluNet
- WHO Influenza at the human-animal interface
- Centers for Disease Control and Prevention seasonal influenza report
- European Centre for Disease Prevention and Control - epidemiological data
- South Africa Influenza surveillance report
- New Zealand Public Health Surveillance
- Australia Influenza Report
- Pan-American Health Organization Influenza Situation Report
FluWatch definitions for the 2015-2016 season
Abbreviations: Newfoundland/Labrador (NL), Prince Edward Island (PE), New Brunswick (NB), Nova Scotia (NS), Quebec (QC), Ontario (ON), Manitoba (MB), Saskatchewan (SK), Alberta (AB), British Columbia (BC), Yukon (YT), Northwest Territories (NT), Nunavut (NU).
Influenza-like-illness (ILI): Acute onset of respiratory illness with fever and cough and with one or more of the following - sore throat, arthralgia, myalgia, or prostration which is likely due to influenza. In children under 5, gastrointestinal symptoms may also be present. In patients under 5 or 65 and older, fever may not be prominent.
Greater than 10% absenteeism (or absenteeism that is higher (e.g. >5-10%) than expected level as determined by school or public health authority) which is likely due to ILI.
Note: it is recommended that ILI school outbreaks be laboratory confirmed at the beginning of influenza season as it may be the first indication of community transmission in an area.
- Hospitals and residential institutions:
- two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case. Institutional outbreaks should be reported within 24 hours of identification. Residential institutions include but not limited to long-term care facilities ( LTCF) and prisons.
- Greater than 10% absenteeism on any day which is most likely due to ILI.
- Other settings:
- two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case; i.e. closed communities.
Note that reporting of outbreaks of influenza/ILI from different types of facilities differs between jurisdictions.
Influenza/ILI activity level
1 = No activity: no laboratory-confirmed influenza detections in the reporting week, however, sporadically occurring ILI may be reported
3 = Localized:
4 = Widespread:
Note: ILI data may be reported through sentinel physicians, emergency room visits or health line telephone calls.
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