FluWatch report: April 26 to May 2, 2015 (Week 17)
Posted 2015-05-08 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: April 26 to May 2, 2015 (Week 17) (PDF Version - 913 KB - 10 pages)
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Overall Summary
Are you a primary health care practitioner (General Practitioner, Nurse Practitioner or Registered Nurse) interested in becoming a FluWatch sentinel for the 2014-15 influenza season? Contact us at FluWatch@phac-aspc.gc.ca
Influenza/ILI Activity (geographic spread)
In week 17, one region in QC and one region in NL reported widespread activity. Twelve regions reported localized activity: SK, MB, ON(7), QC, NL and NB. Twenty-five regions reported sporadic activity: NT, BC(4), AB(5), SK(2), MB(3), QC(4), NL, NB(4), and NS. Nineteen regions reported no activity: YK, NT, NU(3), BC, MB, NL, NB(2), NS(8), and PE.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Influenza and Other Respiratory Virus Detections
In week 17, the percentage positive for influenza A (0.9%) and B (9.2%) declined from the previous week (Figure 2). Influenza B remained the predominant virus in week 17, representing 90% of influenza detections. Most jurisdictions reported stable or declining levels of influenza detections over recent weeks. To date, 82% of influenza detections have been influenza A, and 99.6% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 36,155 cases (Table 2). Adults ≥65 years of age have predominantly been affected by influenza A, accounting for 62% of influenza A detections. Influenza B, while much smaller in numbers, is mainly affecting individuals less than 65 years of age, they account for 59% of influenza B detections.
In week 17, detections for all other respiratory viruses decreased from the previous week (Figure 3). In recent weeks, detections of human metapneumovirus and parainfluenza have been higher than those reported in each of the past three seasons.
For more details, see the weekly Respiratory Virus Detections in Canada Report.
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015
Antiviral Resistance
During the 2014-2015 influenza season, the NML has tested 1,382 influenza viruses for resistance to oseltamivir and 1,379 influenza viruses for resistance to zanamivir. All viruses were sensitive to zanamivir and one influenza A(H3N2) virus was resistant to oseltamivir. A total of 1,351 influenza A viruses (99.9%) were resistant to amantadine (Table 3).
Influenza Strain Characterizations
During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 750 influenza viruses [185 A(H3N2), 15 A(H1N1) and 550 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=185), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 179 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,105 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,103 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Fifteen A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 550 influenza B viruses characterized, 523 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 24 were B/Brisbane/60/2008-like (Figure 4).
The NML receives a proportion of the number of influenza positive specimens from provincial laboratories for strain characterization and antiviral resistance testing. Characterization data reflect the results of haemagglutination inhibition (HAI) testing compared to the reference influenza strains recommended byWHO.
The recommended components for the 2014-2015 northern hemisphere trivalent influenza vaccine include: an A/California/7/2009(H1N1)pdm09-like virus, an A/Texas/50/2012 (H3N2)-like virus, and a B/Massachusetts/2/2012-like virus (Yamagata lineage). For quadrivalent vaccines, the addition of a B/Brisbane/60/2008-like virus is recommended.
Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate
In week 17, the national influenza-like-illness (ILI) consultation rate declined from the previous week to 18.7 consultations per 1,000 (Figure 5).
Text equivalent for figure 5Influenza-like-illness (ILI) consultation rates by report week, compared to the 1996-97 through to 2012-13 seasons (with pandemic data suppressed), Canada, 2014-2015
Influenza Outbreak Surveillance
In week 17, eight new outbreaks of influenza were reported. All outbreaks were reported in long-term care facilities (LTCF) (Figure 6). and three of the eight outbreaks were associated with influenza B. To date this season, 1,254 outbreaks in LTCFs have been reported and the majority of those with known subtypes were attributable to A(H3N2). There have been a higher number of reported influenza outbreaks to date this season compared to the same period in previous seasons.
Figure 6. Overall number of new influenza outbreaks by report week, Canada, 2014-2015
Text equivalent for figure 6Overall number of new influenza outbreaks by report week, Canada, 2014-2015
Pharmacy Surveillance
Pharmacy surveillance for sales of influenza antivirals has ended for the 2014-2015 influenza season (Figure 7).
Text equivalent for figure 7Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15
Sentinel Hospital Influenza Surveillance
Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 17, nine laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. All cases were influenza B (Figure 8a). A greater proportion of cases have been reported with influenza B in recent weeks, following the trend in laboratory detections. Among the reported cases, four (44%) were <2 years of age and five (56%) were 2 to 9 years of age. No ICU cases were reported.
To date this season, 676 hospitalizations have been reported by the IMPACT network, 509 (75%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 98% (161/164) were A(H3N2) (Table 4). To date, 83 cases were admitted to the ICU, of which 46 (55%) were 2 to 9 years of age (Figure 9a). A total of 54 ICU cases reported to have at least one underlying condition or comorbidity. Four deaths have been reported.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associated paediatric hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Adult Influenza Hospitalizations and Deaths (PCIRN)
In week 17, five laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network. All reported cases were influenza B. Three cases (60%) were in adults over the age of 65 (Figure 8b).
To date this season, 2,228 cases have been reported; 1,912 (86%) with influenza A. The majority of cases (81%) were among adults ≥65 years of age (Table 5). One hundred and seventy two ICU admissions have been reported and 128 cases were adults ≥65 years of age. Among the 172 ICU admissions, 27 were due to influenza B (12 in adults 45 to 64 years of age and 15 in adults over the age of 65). A total of 123 ICU cases (72%) reported to have at least one underlying condition or comorbidity. Of the 123 ICU cases with known immunization status, 40 (33%) reported not having been vaccinated this season. One hundred and thirty-five deaths have been reported, 124 (92%) of the deaths were adults >65 years of age (Figure 9B).
Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associated adult hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Figure 8 - Number of cases of influenza reported by sentinel hospital networks, by week, Canada, 2014-15
A) Paediatric hospitalizations (≤16 years of age, IMPACT)
Text equivalent for figure 8aNumber of cases of influenza reported by sentinel hospital networks, by week, Canada, 2014-15: Paediatric hospitalizations (≤16 years of age, IMPACT)
B) Adult hospitalizations (≥16 year of age, PCIRN-SOS)
* See footnote above following the section related to PCIRN-SOS data.
Text equivalent for figure 8bNumber of cases of influenza reported by sentinel hospital networks, by week, Canada, 2014-15: Adult hospitalizations (>16 year of age, PCIRN-SOS)
Figure 9 - Percentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2014-15
A) Paediatric hospitalizations (≤16 years of age, IMPACT)
Text equivalent for figure 9aPercentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2014-15: Paediatric hospitalizations (≤16 years of age, IMPACT)
B) Adult hospitalizations (≥16 year of age, PCIRN-SOS)
Text equivalent for figure 9bPercentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2014-15: Adult hospitalizations (≥16 year of age, PCIRN-SOS)
Provincial/Territorial Influenza Hospitalizations and Deaths
In week 17, 88 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*, which is lower than the number reported the previous week. Of the 88 hospitalizations, 53 (60%) were due to influenza A and 45 (51%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 7,375 hospitalizations have been reported; 6,471 (88%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.3% were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 384 ICU admissions have been reported to date: 53% (n=202) were in adults ≥65 years of age and 33% (n=128) were in adults 20-64 years. A total of 555 deaths have been reported since the start of the season: three children <5 years of age, four children 5-19 years, 42 adults 20-64 years, and 506 adults ≥65 years of age. Adults 65 years of age or older represent 91% of all deaths reported this season. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases
* Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not distinguished among hospital admissions reported from Ontario. Data may also include cases reported by the IMPACT and PCIRN networks. The number of new influenza-associated hospitalizations and deaths reported for the current week may include cases from Ontario that occurred in previous weeks, as a result of retrospective updates to the cumulative total. It is important to note that the hospitalization or death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting.
See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.
Emerging Respiratory Pathogens
Human Avian Influenza
Influenza A(H7N9): Since the last FluWatch report, no new laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus were reported by the World Health Organization. Globally to May 5, 2015, the WHO reported a total of 651 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 225 deaths. Documents related to the public health risk of influenza A(H7N9), as well as guidance for health professionals and advice for the public is updated regularly on the following websites:
PHAC - Avian influenza A(H7N9)
WHO - Avian Influenza A(H7N9)
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, no new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to May 5, 2015, the WHO has reported a total of 1,110 laboratory-confirmed cases of infection with MERS-CoV, including 422 deaths. All cases have either occurred in the Middle East or have had direct links to a primary case infected in the Middle East. The public health risk posed by MERS-CoV in Canada remains low (see the PHAC Assessment of Public Health Risk) and for the latest global risk assessment posted by the WHO on February 5, 2015: WHO MERS-CoV
Documents related to the public health risk of MERS-CoV, as well as guidance for health professionals and advice for the public is updated regularly on the following websites:
PHAC - Middle East respiratory syndrome coronavirus (MERS-CoV)
WHO - Coronavirus infections
Avian Influenza A(H5)
The Canadian Food Inspection Agency (CFIA) is continuing its investigation into the second outbreak of highly pathogenic avian influenza H5N2 virus in Oxford County, Ontario. To date, there has been three infected commercial premises. Individual quarantines and Avian Influenza Control Zones have been established. No human cases have been reported. Avian influenza viruses do not pose risks to food safety when poultry and poultry products are properly handled and cooked. Avian influenza rarely affects humans that do not have consistent contact with infected birds. Further information on the outbreak is provided on the following CFIA website:
CFIA - Notifiable Avian Influenza
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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php
Posted 2015-05-08 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: April 26 to May 2, 2015 (Week 17) (PDF Version - 913 KB - 10 pages)
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Overall Summary
- Influenza B continues to be the most common influenza virus circulating in Canada; however, influenza B is past its peak and remains within expected levels for this time of year.
- Overall, influenza activity in Canada continues to decline; however, elevated activity was still reported in week 17 (mostly in Central Canada and parts of the Atlantic Provinces).
- Influenza B is having a greater impact on adults less than 65 years of age, compared to influenza A(H3N2), which predominated earlier in the season.
- Fewer influenza hospitalizations were reported this week compared to the previous week. The majority of hospitalizations were due to influenza A and in adults ≥65 years of age.
Are you a primary health care practitioner (General Practitioner, Nurse Practitioner or Registered Nurse) interested in becoming a FluWatch sentinel for the 2014-15 influenza season? Contact us at FluWatch@phac-aspc.gc.ca
Influenza/ILI Activity (geographic spread)
In week 17, one region in QC and one region in NL reported widespread activity. Twelve regions reported localized activity: SK, MB, ON(7), QC, NL and NB. Twenty-five regions reported sporadic activity: NT, BC(4), AB(5), SK(2), MB(3), QC(4), NL, NB(4), and NS. Nineteen regions reported no activity: YK, NT, NU(3), BC, MB, NL, NB(2), NS(8), and PE.
Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 17
Note: Influenza/ILI activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates and reported outbreaks. Please refer to detailed definitions at the end of the report. Maps from previous weeks, including any retrospective updates, are available on the FluWatch website.Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Influenza and Other Respiratory Virus Detections
In week 17, the percentage positive for influenza A (0.9%) and B (9.2%) declined from the previous week (Figure 2). Influenza B remained the predominant virus in week 17, representing 90% of influenza detections. Most jurisdictions reported stable or declining levels of influenza detections over recent weeks. To date, 82% of influenza detections have been influenza A, and 99.6% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 36,155 cases (Table 2). Adults ≥65 years of age have predominantly been affected by influenza A, accounting for 62% of influenza A detections. Influenza B, while much smaller in numbers, is mainly affecting individuals less than 65 years of age, they account for 59% of influenza B detections.
Figure 2. Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, 2014-15
Text equivalent for figure 2Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, 2014-15
In week 17, detections for all other respiratory viruses decreased from the previous week (Figure 3). In recent weeks, detections of human metapneumovirus and parainfluenza have been higher than those reported in each of the past three seasons.
For more details, see the weekly Respiratory Virus Detections in Canada Report.
Figure 3. Number of positive laboratory tests for other respiratory viruses by report week, Canada, 2014-15
RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015
B Total | B Total | |||||||||
1 Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. 2 Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. |
||||||||||
2 | 0 | 0 | 2 | 30 | 3519 | 28 | 2626 | 865 | 415 | |
0 | 0 | 0 | 0 | 37 | 3699 | 14 | 3531 | 154 | 881 | |
1 | 0 | 0 | 1 | 16 | 1314 | 0 | 839 | 475 | 272 | |
0 | 0 | 0 | 0 | 20 | 1122 | 0 | 390 | 732 | 185 | |
9 | 0 | 8 | 1 | 80 | 11149 | 48 | 4709 | 6392 | 1297 | |
21 | 0 | 0 | 21 | 129 | 11408 | 4 | 422 | 11003 | 3737 | |
2 | 0 | 1 | 1 | 21 | 1195 | 0 | 193 | 1002 | 505 | |
0 | 0 | 0 | 0 | 4 | 511 | 1 | 123 | 387 | 258 | |
0 | 0 | 0 | 0 | 0 | 131 | 1 | 128 | 2 | 108 | |
2 | 0 | 0 | 2 | 7 | 622 | 0 | 123 | 499 | 48 | |
37 | 0 | 9 | 28 | 344 | 34691 | 96 | 13084 | 21511 | 7706 | |
9.7% | 0.0% | 24.3% | 75.7% | 90.3% | 81.8% | 0.3% | 37.7% | 62.0% | 18.2% |
Total | Total | |||||||||||
1 Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. 2 Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. 3 Table 2 includes specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. |
||||||||||||
4 | 0 | 0 | 4 | 13 | 2091 | 22 | 809 | 1260 | 489 | 2580 | 7.1% | |
1 | 0 | 0 | 1 | 21 | 1783 | 6 | 957 | 820 | 709 | 2492 | 6.8% | |
2 | 0 | 0 | 2 | 33 | 3436 | 16 | 1669 | 1751 | 970 | 44406 | 12.1% | |
3 | 0 | 1 | 2 | 41 | 3863 | 21 | 1658 | 2184 | 1626 | 5489 | 15.1% | |
13 | 0 | 2 | 11 | 95 | 18721 | 15 | 7280 | 11426 | 2646 | 21367 | 58.6% | |
0 | 0 | 0 | 0 | 0 | 120 | 0 | 101 | 19 | 7 | 127 | 0.3% | |
23 | 0 | 3 | 20 | 203 | 30014 | 80 | 12474 | 17460 | 6447 | 36461 | 100.0% | |
10.2% | 0.0% | 13.0% | 87.0% | 89.8% | 82.3% | 0.3% | 41.6% | 58.2% | 17.7% |
During the 2014-2015 influenza season, the NML has tested 1,382 influenza viruses for resistance to oseltamivir and 1,379 influenza viruses for resistance to zanamivir. All viruses were sensitive to zanamivir and one influenza A(H3N2) virus was resistant to oseltamivir. A total of 1,351 influenza A viruses (99.9%) were resistant to amantadine (Table 3).
* NA - not applicable | ||||||
876 | 1 | 874 | 0 | 1338 | 1337 (99.9%) | |
10 | 0 | 10 | 0 | 14 | 14 (100%) | |
496 | 0 | 495 | 0 | NA * | NA * | |
1382 | 1 | 1379 | 0 | 1352 | 1351 |
During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 750 influenza viruses [185 A(H3N2), 15 A(H1N1) and 550 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=185), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 179 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,105 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,103 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Fifteen A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 550 influenza B viruses characterized, 523 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 24 were B/Brisbane/60/2008-like (Figure 4).
Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 750
The NML receives a proportion of the number of influenza positive specimens from provincial laboratories for strain characterization and antiviral resistance testing. Characterization data reflect the results of haemagglutination inhibition (HAI) testing compared to the reference influenza strains recommended byWHO.
The recommended components for the 2014-2015 northern hemisphere trivalent influenza vaccine include: an A/California/7/2009(H1N1)pdm09-like virus, an A/Texas/50/2012 (H3N2)-like virus, and a B/Massachusetts/2/2012-like virus (Yamagata lineage). For quadrivalent vaccines, the addition of a B/Brisbane/60/2008-like virus is recommended.
Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate
In week 17, the national influenza-like-illness (ILI) consultation rate declined from the previous week to 18.7 consultations per 1,000 (Figure 5).
Figure 5. Influenza-like-illness (ILI) consultation rates by report week, compared to the 1996-97 through to 2012-13 seasons (with pandemic data suppressed), Canada, 2014-2015
Note: No data available for mean rate for weeks 19 to 39 for the 1996-1997 through 2002-2003 seasons. Delays in the reporting of data may cause data to change retrospectively. The calculation of the average ILI consultation rate over 17 seasons was aligned with influenza activity in each season. In BC, AB, and SK, data is compiled by a provincial sentinel surveillance program for reporting to FluWatch. Not all sentinel physicians report every week.
Text equivalent for figure 5Influenza-like-illness (ILI) consultation rates by report week, compared to the 1996-97 through to 2012-13 seasons (with pandemic data suppressed), Canada, 2014-2015
Influenza Outbreak Surveillance
In week 17, eight new outbreaks of influenza were reported. All outbreaks were reported in long-term care facilities (LTCF) (Figure 6). and three of the eight outbreaks were associated with influenza B. To date this season, 1,254 outbreaks in LTCFs have been reported and the majority of those with known subtypes were attributable to A(H3N2). There have been a higher number of reported influenza outbreaks to date this season compared to the same period in previous seasons.
Figure 6. Overall number of new influenza outbreaks by report week, Canada, 2014-2015
1 All provinces and territories except NU report outbreaks in long-term care facilities. All provinces and territories with the exception of NU and QC report outbreaks in hospitals. Outbreaks of influenza or influenza-like-illness in other facilities are reported to FluWatch but reporting varies between jurisdictions. Outbreak definitions are included at the end of the report.
Text equivalent for figure 6Overall number of new influenza outbreaks by report week, Canada, 2014-2015
Pharmacy Surveillance
Pharmacy surveillance for sales of influenza antivirals has ended for the 2014-2015 influenza season (Figure 7).
Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 2,500 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group. Age-groups: Infant: 0-2y, Child: 2-18y; Adult: 19-64y, Senior: ≥65y
Text equivalent for figure 7Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15
Sentinel Hospital Influenza Surveillance
Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 17, nine laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. All cases were influenza B (Figure 8a). A greater proportion of cases have been reported with influenza B in recent weeks, following the trend in laboratory detections. Among the reported cases, four (44%) were <2 years of age and five (56%) were 2 to 9 years of age. No ICU cases were reported.
To date this season, 676 hospitalizations have been reported by the IMPACT network, 509 (75%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 98% (161/164) were A(H3N2) (Table 4). To date, 83 cases were admitted to the ICU, of which 46 (55%) were 2 to 9 years of age (Figure 9a). A total of 54 ICU cases reported to have at least one underlying condition or comorbidity. Four deaths have been reported.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associated paediatric hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Adult Influenza Hospitalizations and Deaths (PCIRN)
In week 17, five laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) network. All reported cases were influenza B. Three cases (60%) were in adults over the age of 65 (Figure 8b).
To date this season, 2,228 cases have been reported; 1,912 (86%) with influenza A. The majority of cases (81%) were among adults ≥65 years of age (Table 5). One hundred and seventy two ICU admissions have been reported and 128 cases were adults ≥65 years of age. Among the 172 ICU admissions, 27 were due to influenza B (12 in adults 45 to 64 years of age and 15 in adults over the age of 65). A total of 123 ICU cases (72%) reported to have at least one underlying condition or comorbidity. Of the 123 ICU cases with known immunization status, 40 (33%) reported not having been vaccinated this season. One hundred and thirty-five deaths have been reported, 124 (92%) of the deaths were adults >65 years of age (Figure 9B).
Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associated adult hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
1 Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. |
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81 | 0 | 18 | 63 | 12 | 93 (13.8%) | |
114 | 2 | 36 | 76 | 34 | 148 (21.9%) | |
124 | 1 | 38 | 85 | 45 | 169 (25.0%) | |
129 | 0 | 44 | 85 | 49 | 178 (26.3%) | |
61 | 0 | 25 | 36 | 27 | 88 (13.0%) | |
509 | 3 | 161 | 345 | 167 | 676 | |
75.3% | 0.6% | 31.6% | 67.8% | 24.7% | 100.0% |
1 Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. |
||||||
3 | 0 | 1 | 2 | 1 | 4 (%) | |
106 | 1 | 56 | 49 | 16 | 122 (5%) | |
217 | 3 | 99 | 115 | 76 | 293 (13%) | |
1586 | 4 | 760 | 822 | 223 | 1809 (81%) | |
1912 | 8 | 916 | 988 | 316 | 2228 | |
86% | 0% | 48% | 52% | 14% | 100% |
A) Paediatric hospitalizations (≤16 years of age, IMPACT)
Text equivalent for figure 8aNumber of cases of influenza reported by sentinel hospital networks, by week, Canada, 2014-15: Paediatric hospitalizations (≤16 years of age, IMPACT)
B) Adult hospitalizations (≥16 year of age, PCIRN-SOS)
* See footnote above following the section related to PCIRN-SOS data.
Text equivalent for figure 8bNumber of cases of influenza reported by sentinel hospital networks, by week, Canada, 2014-15: Adult hospitalizations (>16 year of age, PCIRN-SOS)
Figure 9 - Percentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2014-15
A) Paediatric hospitalizations (≤16 years of age, IMPACT)
Text equivalent for figure 9aPercentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2014-15: Paediatric hospitalizations (≤16 years of age, IMPACT)
B) Adult hospitalizations (≥16 year of age, PCIRN-SOS)
Text equivalent for figure 9bPercentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2014-15: Adult hospitalizations (≥16 year of age, PCIRN-SOS)
Provincial/Territorial Influenza Hospitalizations and Deaths
In week 17, 88 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*, which is lower than the number reported the previous week. Of the 88 hospitalizations, 53 (60%) were due to influenza A and 45 (51%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 7,375 hospitalizations have been reported; 6,471 (88%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.3% were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 384 ICU admissions have been reported to date: 53% (n=202) were in adults ≥65 years of age and 33% (n=128) were in adults 20-64 years. A total of 555 deaths have been reported since the start of the season: three children <5 years of age, four children 5-19 years, 42 adults 20-64 years, and 506 adults ≥65 years of age. Adults 65 years of age or older represent 91% of all deaths reported this season. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases
* Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not distinguished among hospital admissions reported from Ontario. Data may also include cases reported by the IMPACT and PCIRN networks. The number of new influenza-associated hospitalizations and deaths reported for the current week may include cases from Ontario that occurred in previous weeks, as a result of retrospective updates to the cumulative total. It is important to note that the hospitalization or death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting.
Total | # (%) | ||||||
1 Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. UnS: unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. |
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422 | 3 | 150 | 269 | 73 | 495 (7%) | ||
277 | 2 | 133 | 142 | 95 | 372 (5%) | ||
385 | 4 | 232 | 149 | 104 | 489 (7%) | ||
614 | 9 | 261 | 344 | 124 | 738 (10%) | ||
4717 | 3 | 2245 | 2469 | 488 | 5205 (71%) | ||
56 | 1 | 52 | 3 | 20 | 76 (1%) | ||
6471 | 22 | 3073 | 3376 | 904 | 7375 | ||
87.7% | 0.3% | 47.5% | 52.2% | 12.3% | 100.0% |
Emerging Respiratory Pathogens
Human Avian Influenza
Influenza A(H7N9): Since the last FluWatch report, no new laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus were reported by the World Health Organization. Globally to May 5, 2015, the WHO reported a total of 651 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 225 deaths. Documents related to the public health risk of influenza A(H7N9), as well as guidance for health professionals and advice for the public is updated regularly on the following websites:
PHAC - Avian influenza A(H7N9)
WHO - Avian Influenza A(H7N9)
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, no new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to May 5, 2015, the WHO has reported a total of 1,110 laboratory-confirmed cases of infection with MERS-CoV, including 422 deaths. All cases have either occurred in the Middle East or have had direct links to a primary case infected in the Middle East. The public health risk posed by MERS-CoV in Canada remains low (see the PHAC Assessment of Public Health Risk) and for the latest global risk assessment posted by the WHO on February 5, 2015: WHO MERS-CoV
Documents related to the public health risk of MERS-CoV, as well as guidance for health professionals and advice for the public is updated regularly on the following websites:
PHAC - Middle East respiratory syndrome coronavirus (MERS-CoV)
WHO - Coronavirus infections
Avian Influenza A(H5)
The Canadian Food Inspection Agency (CFIA) is continuing its investigation into the second outbreak of highly pathogenic avian influenza H5N2 virus in Oxford County, Ontario. To date, there has been three infected commercial premises. Individual quarantines and Avian Influenza Control Zones have been established. No human cases have been reported. Avian influenza viruses do not pose risks to food safety when poultry and poultry products are properly handled and cooked. Avian influenza rarely affects humans that do not have consistent contact with infected birds. Further information on the outbreak is provided on the following CFIA website:
CFIA - Notifiable Avian Influenza
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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php
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