Canada FluWatch Weekly Reports 2014-2015 Season Week 20

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May 29, 2015, 03:31 PM

FluWatch report: May 17 to May 23, 2015 (Week 20)

Posted 2015-05-29 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: May 17 to May 23, 2015 (Week 20) (PDF Version - 915 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 decrease as we approach the end of the influenza season.
Based on laboratory detections, 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.
As of week 20, 7,602 hospitalizations and 579 deaths have been reported from participating regions, which is more than were reported last year at this time (4,867 hospitalizations and 293 deaths).

Please Note: This is the final weekly report for the 2014-15 influenza season. Bi-weekly reports will start on June 12th (for weeks 21 and 22). Laboratory detections reported through the RVDSS will be updated weekly on the FluWatch website.
Influenza/ILI Activity (geographic spread)

In week 20, nine regions reported localized activity: BC, ON(5), QC and NL(2). Twenty-one regions reported sporadic activity: BC(3), AB(5), SK(3), MB(2), ON(2), QC(5), and NB.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 20

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

The number of positive influenza tests decreased from 233 in week 19 to 124 in week 20. Influenza B remained the predominant virus in week 20, representing 98% of influenza detections. All jurisdictions reported declining levels of influenza detections this week. To date, 81% of influenza detections have been influenza A (Table 1). To date this season, detailed information on age and type/subtype has been received for 37,126 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. Adults under the age of 64 years accounted 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 20, detections for all other respiratory viruses decreased from the previous week and are approaching inter-seasonal levels (figure 3).
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
0	0	0	0	14	3525	28	2629	868	480
1	0	1	0	21	3702	14	3533	155	957
0	0	0	0	9	1315	0	839	476	334
0	0	0	0	6	1124	1	390	733	220
2	0	0	2	33	11164	50	4714	6400	1498
0	0	0	0	32	11449	4	422	11023	3902
0	0	0	0	0	1195	0	193	1002	530
0	0	0	0	0	511	1	123	387	261
0	0	0	0	0	131	1	128	2	108
0	0	0	0	6	629	0	123	506	76
3	0	1	2	121	34745	99	13094	21552	8366
2.4%	0.0%	33.3%	66.7%	97.6%	80.6%	0.3%	37.7%	62.0%	19.4%

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
0	0	0	0	10	2091	22	809	1260	541	2632	7.1%
0	0	0	0	17	1781	6	956	819	774	2555	6.9%
0	0	0	0	20	3443	17	1673	1753	1094	4537	12.2%
0	0	0	0	15	3874	22	1659	2193	1783	5657	15.2%
1	0	1	0	30	18746	15	7290	11441	2872	21618	58.2%
0	0	0	0	0	120	0	101	19	7	127	0.3%
1	0	1	0	92	30055	82	12488	17485	7071	37126	100.0%
1.1%	0.0%	100.0%	0.0%	98.9%	81.0%	0.3%	41.6%	58.2%	19.0%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,561 influenza viruses for resistance to oseltamivir and 1,559 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 1,427 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
901	1	900	0	1408	1407 (99.9%)
18	0	18	0	20	20 (100%)
642	0	641	0	NA ^*	NA ^*
1561	1	1559	0	1428	1427

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 961 influenza viruses [198 A(H3N2), 21 A(H1N1) and 742 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=198), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 192 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,160 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,158 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Twenty-one A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 742 influenza B viruses characterized, 683 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 56 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 961

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

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

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Influenza Outbreak Surveillance

In week 20, four new outbreaks of influenza were reported. Two outbreaks were reported in long-term care facilities (LTCF) and two in institutional or community settings (Figure 6). To date this season, 1,275 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 laboratory-confirmed influenza outbreaks by report week, Canada, 2014-2015

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

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 20, 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, two (22%) were <2 years of age, three (33%) were 2 to 9 years of age and four (44%) were 10 to 16 years of age. One ICU admission was reported.
To date this season, 697 hospitalizations have been reported by the IMPACT network, 510 (73%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 98% (162/165) were A(H3N2) (Table 4). To date, 88 cases were admitted to the ICU, of which 48 (55%) were 2 to 9 years of age (Figure 9a). A total of 55 ICU cases reported to have at least one underlying condition or comorbidity. Five 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)
Surveillance has ended for the 2014-2015 influenza season.
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.
82	0	19	63	14	96 (13.8%)
114	2	36	76	40	154 (22.1%)
124	1	38	85	49	173 (24.8%)
129	0	44	85	51	180 (25.8%)
61	0	25	36	33	94 (13.5%)
510	3	162	345	187	697
73.2%	0.6%	31.8%	67.6%	26.8%	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%

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)

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 20, 38 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*. Of the 38 hospitalizations, 25 (66%) were due to influenza A and 22 (58%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 7,602 hospitalizations have been reported; 6,565 (86%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.1% were A(H3N2). The majority of cases (70%) were ≥65 years of age (Table 6). A total of 391 ICU admissions have been reported to date: 52% (n=203) were in adults ≥65 years of age and 75% were due to influenza A. A total of 579 deaths have been reported since the start of the season: three children <5 years of age, four children 5-19 years, 43 adults 20-64 years, and 529 adults ≥65 years of age. Influenza A has been reported in 91% of deaths. 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, and QC. 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.

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.
426	6	150	270	85	511 (7%)
258	0	120	138	93	351 (5%)
322	4	169	149	80	402 (5%)
720	12	354	354	203	923 (12%)
4783	5	2291	2487	554	5337 (70%)
56	1	52	3	22	78 (1%)
6565	28	3136	3401	1037	7602
86.4%	0.4%	47.8%	51.8%	13.6%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.
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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

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Pathfinder replied

May 22, 2015, 05:34 PM

FluWatch report: May 10 to May 16, 2015 (Week 19)

Posted 2015-05-22 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: May 10 to May 16, 2015 (Week 19) (PDF Version - 916 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 decrease; however, elevated activity was still reported in week 19 (mostly in parts of Central Canada and Newfoundland).
Based on laboratory detections, 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.
As of week 19, 7,549 hospitalizations and 576 deaths have been reported from participating regions, which is more than were reported last year at this time (4,862 hospitalizations and 291 deaths).

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 19

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

The number of positive influenza tests decreased from 314 in week 18 to 220 in week 19. Influenza B remained the predominant virus in week 19, representing 93% of influenza detections. Most jurisdictions reported stable or declining levels of influenza detections over recent weeks. To date, 81% of influenza detections have been influenza A, and 99.2% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 36,997 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. Adults under the age of 64 years accounted 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 19, detections for all other respiratory viruses decreased from the previous week and are approaching inter-seasonal levels (figure 3).
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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	0	3	33	3525	28	2629	868	466
1	0	0	1	25	3701	14	3531	156	937
0	0	0	0	11	1315	0	839	476	311
0	0	0	0	17	1124	1	390	733	214
3	0	3	0	49	11162	50	4714	6398	1456
4	0	0	4	50	11449	4	422	11023	3870
0	0	0	0	6	1195	0	193	1002	530
0	0	0	0	1	511	1	123	387	261
0	0	0	0	0	131	1	128	2	108
5	0	0	5	12	629	0	123	506	70
16	0	3	13	204	34742	99	13092	21551	8223
7.3%	0.0%	18.8%	81.3%	92.7%	80.9%	0.3%	37.7%	62.0%	19.1%

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
0	0	0	0	7	2091	22	809	1260	524	2615	7.1%
0	0	0	0	14	1781	6	956	819	755	2536	6.9%
1	0	1	0	32	3443	16	1672	1755	1065	4508	12.2%
4	0	0	4	36	3874	22	1659	2193	1762	5636	15.2%
2	0	1	1	44	18745	15	7289	11441	2830	21575	58.3%
0	0	0	0	0	120	0	101	19	7	127	0.3%
7	0	2	5	133	30054	81	12486	17487	6943	36997	100.0%
5.0%	0.0%	28.6%	71.4%	95.0%	81.2%	0.3%	41.5%	58.2%	18.8%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,499 influenza viruses for resistance to oseltamivir and 1,444 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 1,390 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
901	1	888	0	1372	1371 (99.9%)
17	0	15	0	19	19 (100%)
581	0	541	0	NA ^*	NA ^*
1499	1	1444	0	1391	1390

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 898 influenza viruses [195 A(H3N2), 18 A(H1N1) and 685 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=195), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 189 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,143 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,141 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Eighteen A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 685 influenza B viruses characterized, 643 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 39 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 898

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

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Influenza Outbreak Surveillance

In week 19, 10 new outbreaks of influenza were reported. Eight outbreaks were reported in long-term care facilities (LTCF) and two in institutional or community settings (Figure 6). Among the outbreaks in which the influenza type was known (n=3), all were associated with influenza B. To date this season, 1,273 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 laboratory-confirmed influenza outbreaks by report week, Canada, 2014-2015

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 19, three 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, two (67%) were <2 years of age and one (33%) was 10 to 16 years of age. No ICU admissions were reported.
To date this season, 685 hospitalizations have been reported by the IMPACT network, 509 (74%) 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, 85 cases were admitted to the ICU, of which 48 (57%) were 2 to 9 years of age (Figure 9a). A total of 56 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)
Surveillance has ended for the 2014-2015 influenza season.
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.
81	0	18	63	14	95 (13.9%)
114	2	36	76	36	150 (21.9%)
124	1	38	85	47	171 (25.0%)
129	0	44	85	50	179 (26.1%)
61	0	25	36	29	90 (13.1%)
509	3	161	345	176	685
74.3%	0.6%	31.6%	67.8%	25.7%	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%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 19, 37 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*, which is lower than the number reported the previous week. Of the 37 hospitalizations, 20 (54%) were due to influenza A and 15 (41%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 7,549 hospitalizations have been reported; 6,540 (87%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.2% were A(H3N2). The majority of cases (70%) were ≥65 years of age (Table 6). A total of 389 ICU admissions have been reported to date: 53% (n=203) were in adults ≥65 years of age and 76% were due to influenza A. A total of 576 deaths have been reported since the start of the season: three children <5 years of age, four children 5-19 years, 43 adults 20-64 years, and 526 adults ≥65 years of age. Influenza A has been reported in 91% of deaths. 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, and QC. 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.

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.
425	5	150	270	83	508 (7%)
258	0	120	138	90	348 (5%)
321	4	168	149	77	398 (5%)
718	12	352	354	197	915 (12%)
4762	4	2274	2484	541	5303 (70%)
56	1	52	3	21	77 (1%)
6540	26	3116	3398	1009	7549
86.6%	0.4%	47.6%	52.0%	13.4%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.

.../
http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

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May 15, 2015, 05:53 PM

FluWatch report: May 3 to May 9, 2015 (Week 18)

Posted 2015-05-15 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: May 3 to May 9, 2015 (Week 18) (PDF Version - 915 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 decrease; however, elevated activity was still reported in week 18 (mostly in Central Canada and parts of British Columbia).
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.
As of week 18, 7,448 hospitalizations and 562 deaths have been reported from participating regions, which is more than were reported last year at this time (4,731 hospitalizations and 275 deaths).

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 18

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

The number of positive influenza tests decreased from 381 in week 17 to 299 in week 18. Influenza B remained the predominant virus in week 18, representing 89% of influenza detections. Most jurisdictions reported stable or declining levels of influenza detections over recent weeks. To date, 81% of influenza detections have been influenza A, and 99.3% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 36,794 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. Adults under the age of 64 years accounted 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 18, detections for all other respiratory viruses except rhinovirus and human metapneumovirus decreased from the previous week (Figure 3). The percent positive for rhinovirus increased from 13% in week 17 to 20% in week 18.
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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	3	0	18	3522	28	2629	865	433
1	0	0	1	31	3700	14	3531	155	912
0	0	0	0	5	1314	0	839	475	286
2	1	0	1	12	1124	1	390	733	197
8	0	1	7	87	11157	48	4710	6399	1400
16	0	0	16	83	11445	4	422	11019	3820
0	0	0	0	19	1195	0	193	1002	524
0	0	0	0	2	511	1	123	387	260
0	0	0	0	0	131	1	128	2	108
2	0	0	2	10	624	0	123	501	58
32	1	4	27	267	34723	97	13088	21538	7998
10.7%	3.1%	12.5%	84.4%	89.3%	81.3%	0.3%	37.7%	62.0%	18.7%

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
1	0	0	1	10	2092	22	809	1261	508	2600	7.1%
0	0	0	0	20	1783	6	957	820	751	2534	6.9%
3	0	0	3	25	3441	16	1671	1754	1018	4459	12.1%
6	0	0	6	39	3869	21	1658	2190	1705	5574	15.1%
9	0	0	9	78	18739	15	7286	11438	2761	21500	58.4%
0	0	0	0	0	120	0	101	19	7	127	0.3%
19	0	0	19	172	30044	80	12482	17482	6750	36794	100.0%
9.9%	0.0%	0.0%	100.0%	90.1%	81.7%	0.3%	41.5%	58.2%	18.3%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,446 influenza viruses for resistance to oseltamivir and 1,444 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 1,365 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
890	1	888	0	1350	1349 (99.9%)
15	0	15	0	16	16 (100%)
541	0	541	0	NA ^*	NA ^*
1446	1	1444	0	1366	1365

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 849 influenza viruses [190 A(H3N2), 17 A(H1N1) and 642 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=190), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 184 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,129 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,127 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Seventeen A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 642 influenza B viruses characterized, 602 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 37 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 849

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

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Influenza Outbreak Surveillance

In week 18, 14 new outbreaks of influenza were reported: two due to influenza B, one due to influenza A and 11 for which the influenza type was not provided. Eleven outbreaks were reported in long-term care facilities (LTCF) and three in institutional or community settings (Figure 6). To date this season, 1,265 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 laboratory-confirmed influenza outbreaks by report week, Canada, 2014-2015

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 18, six 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, three (50%) were <2 years of age and three (50%) were 2 to 9 years of age. One ICU case was reported.
To date this season, 681 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, 86 cases were admitted to the ICU, of which 49 (57%) were 2 to 9 years of age (Figure 9a). A total of 56 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)
Surveillance has ended for the 2014-2015 influenza season.
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.
81	0	18	63	13	94 (13.8%)
114	2	36	76	35	149 (21.9%)
124	1	38	85	47	171 (25.1%)
129	0	44	85	50	179 (26.3%)
61	0	25	36	27	88 (12.9%)
509	3	161	345	172	681
74.7%	0.6%	31.6%	67.8%	25.3%	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%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 18, 78 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*, which is lower than the number reported the previous week. Of the 78 hospitalizations, 46 (59%) were due to influenza A and 38 (49%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 7,448 hospitalizations have been reported; 6,510 (87%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.3% were A(H3N2). The majority of cases (70%) were ≥65 years of age (Table 6). A total of 382 ICU admissions have been reported to date: 53% (n=202) were in adults ≥65 years of age and 34% (n=128) were in adults 20-64 years. A total of 562 deaths have been reported since the start of the season: three children <5 years of age, four children 5-19 years, 43 adults 20-64 years, and 512 adults ≥65 years of age. Influenza A has been reported in 92% of deaths. 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, and QC. 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.

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.
424	4	150	270	76	500 (7%)
256	0	118	138	86	342 (5%)
319	4	168	147	70	389 (5%)
711	11	347	353	185	896 (12%)
4744	3	2260	2481	500	5244 (70%)
56	1	52	3	21	77 (1%)
6510	23	3095	3392	938	7448
87.4%	0.4%	47.5%	52.1%	12.6%	100.0%

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May 8, 2015, 03:59 PM

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

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.

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

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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
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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%

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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).

^* 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

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).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 750

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

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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

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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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.
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%

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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.
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%

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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April 24, 2015, 05:38 PM

FluWatch report: April 12 to April 18, 2015 (Week 15)

Posted 2015-04-23 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: April 12 to April 18, 2015 (Week 15) (PDF Version - 908 KB - 10 pages)

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Overall Summary

Influenza B continued to be the most common influenza virus circulating in Canada. More influenza B detections have been observed to date this season, compared to the same time last season.
The number of influenza A and B detections remained similar to the previous week. Other circulating respiratory viruses continue to decrease with the end of the 2014-15 influenza season approaching.
Elevated influenza activity was mostly reported in the Central and Atlantic provinces. Widespread activity was reported in two regions in Quebec.
Influenza B is having a greater impact on adults less than 65 years of age, compared to influenza A(H3N2), which circulated earlier in the season.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 15

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 15, the percentage positive for influenza A (2.1%) and B (11.9%) declined from the previous week (Figure 2). Influenza B detections were greater than influenza A in all provinces with the exception of British Columbia. More influenza B has been observed to date this season (6,821) compared to the same time during the 2013-14 season (5,027). To date, 83.5% of influenza detections have been influenza A, and 99.3% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 35,725 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 15, detections for all other respiratory viruses remained similar to, or decreased from, the previous week (Figure 3). Overall, the detections of other respiratory viruses have been declining since peaking in week 5.
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

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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
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
24	3	20	1	22	3512	28	2623	861	364
3	0	1	2	44	3689	13	3520	156	803
0	0	0	0	17	1312	0	839	473	208
1	0	0	1	25	1122	0	390	732	144
34	1	18	15	144	11114	45	4683	6386	1047
15	0	0	15	279	11397	4	422	10971	3433
15	0	6	9	45	1188	0	189	999	435
6	0	0	5	6	511	0	123	387	245
4	0	4	0	5	130	1	127	2	107
3	0	0	3	6	616	0	123	493	35
105	4	49	51	593	34591	91	13039	21460	6821
15.0%	3.8%	46.7%	48.6%	85.0%	83.5%	0.3%	37.7%	62.0%	16.5%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
1	0	0	1	28	2083	20	808	1255	426	2509	7.0%
1	0	0	1	51	1779	6	955	818	679	2458	6.9%
2	0	1	1	43	3429	16	1662	1751	864	4293	12.0%
8	0	2	6	90	3854	18	1652	2184	1467	5321	14.9%
25	0	6	19	197	18677	15	7257	11405	2341	21018	58.8%
0	0	0	0	0	119	0	100	19	7	126	0.4%
37	0	9	28	409	29941	75	12434	17432	5784	35725	100.0%
8.3%	0.0%	24.3%	75.7%	91.7%	83.8%	0.3%	41.5%	58.2%	16.2%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,260 influenza viruses for resistance to oseltamivir and 1,258 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 1,308 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
855	1	853	0	1298	1297 (99.9%)
9	0	9	0	11	11 (100%)
396	0	396	0	NA ^*	NA ^*
1260	1	1258	0	1309	1308

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 666 influenza viruses [180 A(H3N2), 10 A(H1N1) and 476 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=180), six viruses were antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 174 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,071 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,069 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Ten A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 476 influenza B viruses characterized, 452 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 19 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 666

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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased in week 15 to 31.94 consultations per 1,000, which is above expected levels (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

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Influenza Outbreak Surveillance

In week 15, 21 new outbreaks of influenza were reported. Similar to previous weeks, the majority of the outbreaks occurred in the Central and Atlantic provinces. Nineteen outbreaks were reported in long-term care facilities (LTCF), and two in institutional or community settings (Figure 6). Among the outbreaks in which the influenza type was known (n=3), all outbreaks were associated with influenza B. To date this season, 1,231 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

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 15, 19 laboratory-confirmed influenza-associated paediatric (=16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Seventeen 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, three (16%) were <2 years of age, eleven (58%) were 2 to 9 years of age and five (26%) were 10-16 years of age. One ICU admission was reported.
To date this season, 665 hospitalizations have been reported by the IMPACT network, 502 (80%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (162/164) were A(H3N2) (Table 4). To date, 82 cases were admitted to the ICU, of which 45 (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 15, 16 laboratory-confirmed influenza-associated adult (=16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (CIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 15, 12 cases (75%) were in adults over the age of 65 (Figure 8b). One death was reported in week 15 in an adult over the age of 65 years.
To date this season, 2,179 cases have been reported; 1,908 (88%) with influenza A. The majority of cases (81%) were among adults =65 years of age (Table 5). One hundred and sixty two ICU admissions have been reported and 117 cases were adults =65 years of age. Among the 162 ICU admissions, 19 were due to influenza B (ten in adults 45 to 64 years of age and nine in adults over the age of 65). A total of 113 ICU cases (70%) reported to have at least one underlying condition or comorbidity. Of the 118 ICU cases with known immunization status, 38 (32%) reported not having been vaccinated this season. One hundred and thirty deaths have been reported, 120 (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.
81	0	18	63	8	91 (13.7%)
109	1	35	73	29	142 (21.4%)
123	1	40	82	32	165 (24.8%)
129	0	44	85	33	175 (26.3%)
60	0	25	35	25	92 (13.8%)
502	2	162	338	127	665
79.8%	0.4%	32.3%	67.3%	20.2%	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 (%)
105	1	55	49	15	120 (6%)
215	2	97	116	65	280 (13%)
1585	4	755	826	190	1775 (81%)
1908	7	908	993	271	2179
88%	0%	48%	52%	12%	100%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 15, 191 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*, which more than the number reported the previous week. Of the 191 hospitalizations, 156 (82%) were due to influenza A and 125 (64%) were in patients =65 years of age.
Since the start of the 2014-15 season, 7,086 hospitalizations have been reported; 6,345 (90%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.4% were A(H3N2). The majority of cases (71%) were =65 years of age (Table 6). A total of 368 ICU admissions have been reported to date: 52% (n=193) were in adults =65 years of age and 34% (n=124) were in adults 20-64 years. A total of 527 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 478 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.
416	2	150	264	60	476 (7%)
275	2	132	141	81	356 (5%)
380	4	228	148	92	472 (7%)
597	6	255	336	99	696 (10%)
4621	2	2190	2429	391	5012 (71%)
56	1	52	3	18	74 (1%)
6345	17	3007	3321	741	7086
89.5%	0.3%	47.4%	52.3%	10.5%	100.0%

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 April 23, 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)
Influenza A(H5N6): Since the last FluWatch report, no new cases of human infection with avian influenza A (H5N6) virus from China has been reported by the World Health Organization. Globally to April 23, 2015, the WHO has been informed of a total of three cases of avian influenza A (H5N6) virus, including two deaths.
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 April 23, 2015, the WHO has reported a total of 1,106 laboratory-confirmed cases of infection with MERS-CoV, including 421 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 two infected commercial premise. All premises located within the 10 km Avian Influenza Control Zone have been placed under quarantine. 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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April 17, 2015, 04:40 PM

FluWatch report: April 5 to April 11, 2015 (Week 14)

Posted 2015-04-17 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: April 5 to April 11, 2015 (Week 14) (PDF Version - 908 KB - 10 pages)

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Overall Summary

In week 14, influenza B continued to be the predominant influenza virus circulating in all provinces and territories.
The number of influenza A and B detections remained similar to the previous week. Other circulating respiratory viruses continue to decrease with the end of the 2014-15 flu season approaching.
Influenza B is having a greater impact on adults less than 65 years of age, compared to influenza A(H3N2), which circulated earlier in the season.
Evidence from the National Microbiology Laboratory (NML) indicates that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 14

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 14, the percentage positive for influenza A (2.2%) and B (12.2%) declined from the previous week (Figure 2). Influenza B detections were greater than influenza A in all provinces. More influenza B has been observed to date this season (6,130) compared to the same time during the 2013-14 season (5,027). To date, 85% of influenza detections have been influenza A, and 99.3% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 35,137 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 60% 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 14, detections for all other respiratory viruses remained similar to, or decreased from, the previous week (Figure 3). Overall, the detections of other respiratory viruses have been declining since peaking in week 5.
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

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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
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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	0	3	21	3498	25	2603	870	342
6	0	4	2	46	3686	13	3519	154	758
0	0	0	0	9	1312	0	839	473	176
0	0	0	0	16	1121	0	390	731	119
43	0	25	18	110	11077	43	4659	6375	884
24	0	0	24	271	11376	4	422	10950	3119
26	0	3	23	72	1173	0	183	990	390
2	0	0	2	14	505	0	123	382	239
2	0	2	0	12	123	1	120	2	74
1	0	0	1	5	613	0	123	490	29
107	0	34	73	576	34484	86	12981	21417	6130
15.7%	0.0%	31.8%	68.2%	84.3%	84.9%	0.2%	37.6%	62.1%	15.1%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
5	0	1	4	32	2081	19	807	1255	392	2473	7.0%
3	0	1	2	31	1775	6	953	816	577	2352	6.7%
3	0	2	1	36	3426	16	1659	1751	804	4230	12.0%
6	0	3	3	74	3845	17	1646	2182	1354	5199	14.8%
25	0	8	17	188	18637	13	7232	11392	2120	20757	59.1%
0	0	0	0	0	121	0	100	21	5	126	0.4%
42	0	15	27	361	29885	71	12397	17417	5252	35137	100.0%
10.4%	0.0%	35.7%	64.3%	89.6%	85.1%	0.2%	41.5%	58.3%	14.9%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,197 influenza viruses for resistance to oseltamivir and 1,192 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 1,284 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
846	1	843	0	1275	1274 (99.9%)
9	0	9	0	10	10 (100%)
342	0	340	0	NA ^*	NA ^*
1197	1	1192	0	1285	1284

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 611 influenza viruses [179 A(H3N2), 10 A(H1N1) and 422 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=179), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 173 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,054 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,052 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012.
Influenza A(H1N1): Ten A(H1N1) viruses characterized were antigenically similar to A/California/7/2009.
Influenza B: Of the 422 influenza B viruses characterized, 400 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 19 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 611

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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased in week 14 to 49.4 consultations per 1,000, which is above expected levels (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

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Influenza Outbreak Surveillance

In week 14, 26 new outbreaks of influenza were reported. Similar to previous weeks, the majority of the outbreaks occurred in the Central and Atlantic provinces. Twenty outbreaks were reported in long-term care facilities (LTCF), one in hospitals and five in institutional or community settings (Figure 6). Among the outbreaks in which the influenza type was known (n=8), six outbreaks were associated with influenza B. To date this season, 1,212 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

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 14, 15 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Fourteen 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, one (7%) was <2 years of age, ten (67%) were 2 to 9 years of age and four (27%) were 10-16 years of age. One ICU admission was reported.
To date this season, 643 hospitalizations have been reported by the IMPACT network, 502 (80%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (162/164) were A(H3N2) (Table 4). To date, 82 cases were admitted to the ICU, of which 45 (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 14, 30 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 14, 21 cases (70%) were in adults over the age of 65 and 23 cases (77%) had influenza B (Figure 8b).
To date this season, 2,147 cases have been reported; 1,896 (88%) with influenza A. The majority of cases (82%) were among adults ≥65 years of age (Table 5). One hundred and fifty seven ICU admissions have been reported and 119 cases were adults ≥65 years of age. Among the 157 ICU admissions, 15 were due to influenza B (seven in adults 45 to 64 years of age and eight in adults over the age of 65). A total of 111 ICU cases (71%) reported to have at least one underlying condition or comorbidity. Of the 120 ICU cases with known immunization status, 38 (32%) reported not having been vaccinated this season. One hundred and twenty four deaths have been reported, 114 (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.
81	0	18	63	8	89 (13.8%)
109	1	35	73	29	140 (21.8%)
123	1	40	82	32	160 (24.9%)
129	0	44	85	33	167 (26.0%)
60	0	25	35	25	87 (13.5%)
502	2	162	338	127	643
79.8%	0.4%	32.3%	67.3%	20.2%	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 (%)
105	1	55	49	12	117 (5%)
214	2	94	118	61	275 (13%)
1574	3	749	822	177	1751 (82%)
1896	6	899	991	251	2147
88%	0%	47%	52%	12%	100%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 14, 122 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories^*, which is similar to the number reported the previous week. Of the 122 hospitalizations, 84 (69%) were due to influenza A and 78 (64%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 6,847 hospitalizations have been reported; 6,195 (91%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 358 ICU admissions have been reported to date: 53% (n=190) were in adults ≥65 years of age and 33% (n=119) were in adults 20-64 years. A total of 511 deaths have been reported since the start of the season: four children <5 years of age, three children 5-19 years, 41 adults 20-64 years, and 463 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.
408	2	146	260	51	459 (7%)
273	2	133	138	72	345 (5%)
372	3	223	146	78	450 (7%)
579	4	241	334	85	664 (10%)
4507	2	2109	2396	348	4855 (71%)
56	1	52	3	18	74 (1%)
6195	14	2904	3277	652	6847
90.5%	0.2%	46.9%	52.9%	9.5%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.

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April 10, 2015, 04:14 PM

FluWatch report: March 29 to April 04, 2015 (Week 13)

Posted 2015-04-10 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 29 to April 04, 2015 (Week 13) (PDF Version - 902 KB - 10 pages)

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Overall Summary

The majority of influenza activity continues to occur in the Central and Atlantic province however, less activity was reported this week from these regions.
The number of influenza A and B detections decreased this week.
Influenza B is having a greater impact on adults less than 65 years of age, compared to influenza A(H3N2), which circulated earlier in the season.
Evidence from the National Microbiology Laboratory (NML) indicates that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 13

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 13, the percentage positive for influenza A (3.4%) continued to decline from the previous week while the percentage of positive influenza B tests continued to increase (12.9%) (Figure 2).Influenza B detections were greater than influenza A in all provinces except NS. More influenza B has been observed to date this season (5,521) compared to the same time during the 2013-14 season (4,371). To date, 86% of influenza detections have been influenza A, and 99.3% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 34,604 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 60% 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 13, detections for all other respiratory viruses remained similar to, or decreased from, the previous week (Figure 3). Overall, the detections of other respiratory viruses have been declining since peaking in week 5.
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
B Total	B Total
7	0	0	7	24	3495	25	2603	867	321
14	0	11	3	45	3680	13	3513	154	712
1	0	0	1	10	1312	0	839	473	150
1	0	1	0	13	1121	0	390	731	103
60	1	25	34	104	11028	43	4633	6352	758
20	0	0	20	274	11352	4	422	10926	2848
30	0	5	25	62	1147	0	180	967	318
16	0	0	16	16	503	0	123	380	225
1	0	1	0	16	121	1	118	2	62
2	0	0	2	5	612	0	123	489	24
152	1	43	108	569	34371	86	12944	21341	5521
21.1%	0.7%	28.3%	71.1%	78.9%	86.2%	0.3%	37.7%	62.1%	13.8%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
3	0	0	3	32	2073	18	805	1250	351	2424	7.0%
4	0	0	4	35	1770	6	951	813	536	2306	6.7%
6	0	0	6	54	3419	16	1652	1751	748	4167	12.0%
7	0	1	6	98	3835	17	1639	2179	1247	5082	14.7%
46	0	17	29	168	18602	13	7215	11374	1897	20499	59.2%
0	0	0	0	0	121	0	100	21	5	126	0.4%
66	0	18	48	387	29820	70	12362	17388	4784	34604	100.0%
14.6%	0.0%	27.3%	72.7%	85.4%	86.2%	0.2%	41.5%	58.3%	13.8%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,121 influenza viruses for resistance to oseltamivir and zanamivir. All viruses were sensitive to zanamivir and one influenza A(H3N2) virus was resistant to oseltamivir. A total of 1,235 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
834	1	834	0	1230	1229 (99.9%)
6	0	6	0	6	6 (100%)
281	0	281	0	NA ^*	NA ^*
1121	1	1121	0	1236	1235

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 558 influenza viruses [179 A(H3N2), 9 A(H1N1) and 370 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=179), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 173 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1,035 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1,033 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012.
Influenza A(H1N1): Nine A(H1N1) viruses characterized were antigenically similar to A/California/7/2009.
Influenza B: Of the 370 influenza B viruses characterized, 351 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 16 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 558

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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased in week 13 to 31.2 consultations per 1,000, which is within expected levels (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

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Influenza Outbreak Surveillance

In week 13, 25 new outbreaks of influenza were reported. The majority of the outbreaks occurred in the Central and Atlantic provinces. Nineteen outbreaks were reported in long-term care facilities (LTCF), one in hospitals and five in institutional or community settings (Figure 6). Among the outbreaks in which the influenza type was known (n=9), seven outbreaks were associated with influenza B. To date this season, 1,192 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

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 13, 10 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. All 10 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, two (20%) were <2 years of age, five (50%) were 2 to 9 years of age and three (30%) were 10-16 years of age. Three ICU admissions were reported.
To date this season, 629 hospitalizations have been reported by the IMPACT network, 502 (80%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (162/164) were A(H3N2) (Table 4).To date, 82 cases were admitted to the ICU, of which 46 (56%) 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 13, 24 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 13, 20 cases (83%) were in adults over the age of 65 and 14 cases (58%) had influenza B (Figure 8b).
To date this season, 2,101 cases have been reported; 1,887 (90%) with influenza A. The majority of cases (82%) were among adults ≥65 years of age (Table 5). One hundred and fifty four ICU admissions have been reported and 116 cases were adults ≥65 years of age. Among the 154 ICU admissions, 12 were due to influenza B (six in adults 45 to 64 years of age and six in adults over the age of 65). A total of 110 ICU cases (73%) reported to have at least one underlying condition or comorbidity. Of the 112 ICU cases with known immunization status, 38 (34%) reported not having been vaccinated this season. One hundred and twenty three deaths have been reported, 113 (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.
81	0	18	63	8	89 (14.1%)
109	1	35	73	29	138 (21.9%)
123	1	40	82	32	155 (24.6%)
129	0	44	85	33	162 (25.8%)
60	0	25	35	25	85 (13.5%)
502	2	162	338	127	629
79.8%	0.4%	32.3%	67.3%	20.2%	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 (%)
105	1	54	50	10	115 (5%)
215	1	92	122	52	267 (13%)
1564	3	734	827	151	1715 (82%)
1887	5	881	1001	214	2101
90%	0%	47%	53%	10%	100%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 13, 120 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories^*, which is less than the number reported the previous week. Of the 120 hospitalizations, 84 (70%) were due to influenza A and 82 (68%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 6,679 hospitalizations have been reported; 6,108 (91.5%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 352 ICU admissions have been reported to date: 53% (n=188) were in adults ≥65 years of age and 33% (n=116) were in adults 20-64 years. A total of 493 deaths have been reported since the start of the season: four children <5 years of age, three children 5-19 years, 40 adults 20-64 years, and 446 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.
401	2	143	256	45	446 (7%)
267	2	130	135	65	332 (5%)
371	3	223	145	72	443 (7%)
572	5	239	328	73	645 (10%)
4441	2	2066	2373	298	4739 (71%)
56	1	52	3	18	74 (1%)
6108	15	2853	3240	571	6679
91.5%	0.2%	46.7%	53.0%	8.5%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.

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April 3, 2015, 04:28 PM

FluWatch report: March 22 to 28, 2015 (Week 12)

Posted 2015-04-02 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 22 to 28, 2015 (Week 12) (PDF Version - 902 KB - 10 pages)

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Overall Summary

The majority of influenza activity continues to occur in the Central and Atlantic provinces.
Influenza B detections continue to increase steadily across Canada while detections of influenza A continues to steadily decrease. This increase in influenza B is expected as influenza B often shows up later in the flu season.
Influenza B is having a greater impact on adults less than 65 years of age, compared to influenza A(H3N2), which circulated earlier in the season.
Evidence from the National Microbiology Laboratory (NML) indicates that this year?s vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 12

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 12, the percentage positive for influenza A (4.7%) continued to decline from the previous week while the percentage of positive influenza B tests continued to increase (11.5%) (Figure 2). Influenza B detections were greater than influenza A in all provinces except NL. To date, 87% of influenza detections have been influenza A, and 99.3% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 33,953 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 60% 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 12, detections for all other respiratory viruses remained similar to, or decreased from, the previous week (Figure 3).
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
26	0	19	7	32	3488	25	2603	860	297
4	0	3	1	58	3666	13	3502	151	667
4	0	2	2	11	1311	0	839	472	131
1	0	1	0	18	1119	0	389	730	90
88	2	40	46	104	10959	41	4606	6312	626
43	0	0	43	365	11332	4	422	10906	2574
75	0	11	64	80	1117	0	175	942	256
23	0	0	23	29	487	0	123	364	209
0	0	0	0	20	120	1	117	2	46
7	0	0	7	6	610	0	53	557	19
271	2	76	193	723	34209	84	12829	21296	4915
27.3%	0.7%	28.0%	71.2%	72.7%	87.4%	0.2%	37.5%	62.3%	12.6%

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
5	1	0	4	31	2069	19	804	1246	305	2374	7.0%
4	0	0	4	33	1760	6	945	809	482	2242	6.6%
6	0	1	5	61	3407	16	1650	1741	669	4076	12.0%
5	0	1	4	133	3814	17	1631	2166	1107	4921	14.5%
72	0	15	57	178	18514	13	7176	11325	1701	20215	59.5%
0	0	0	0	1	120	0	99	21	5	125	0.4%
92	1	17	74	437	29684	71	12305	17308	4269	33953	100.0%
17.4%	1.1%	18.5%	80.4%	82.6%	87.4%	0.2%	41.5%	58.3%	12.6%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,094 influenza viruses for resistance to oseltamivir and 1,090 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 1,235 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
831	1	827	0	1230	1229 (99.9%)
6	0	6	0	6	6 (100%)
257	0	257	0	NA ^*	NA ^*
1094	1	1090	0	1236	1235

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 490 influenza viruses [176 A(H3N2), 9 A(H1N1) and 305 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=176), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 170 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 1025 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 1023 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Nine A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 305 influenza B viruses characterized, 291 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and 14 were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 490

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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased in week 12 to 20.5 consultations per 1,000, which is below expected levels (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

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Influenza Outbreak Surveillance

In week 12, 33 new outbreaks of influenza were reported. The majority of the outbreaks occurred in the Central and Atlantic provinces. Thirty-one outbreaks were reported in long-term care facilities (LTCF) and two in institutional or community settings (Figure 6). Among the outbreaks in which the influenza type was known (n=12), eight outbreaks were associated with influenza B. To date this season, 1,173 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

During week 12, the proportion of prescriptions for antivirals decreased to 110.0 antiviral prescriptions per 100,000 total prescriptions (from 135.8 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups decreased in week 12. The rate was highest among seniors at 176.7 per 100,000 total prescriptions and lowest among infants at 10.4 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 12, 23 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. All 23 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, five (22%) were <2 years of age, ten (43%) were 2 to 9 years of age and eight (35%) were 10-16 years of age. Three ICU admissions were reported.
To date this season, 621 hospitalizations have been reported by the IMPACT network, 503 (81%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (162/164) were A(H3N2) (Table 4). To date, 79 cases were admitted to the ICU, of which 44 (56%) were 2 to 9 years of age (Figure 9a). A total of 51 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 12, 40 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 12, 30 cases (75%) were in adults over the age of 65 and 25 cases (63%) had influenza B (Figure 8b).
To date this season, 2,071 cases have been reported; 1,876 (91%) with influenza A. The majority of cases (82%) were among adults ≥65 years of age (Table 5). One hundred and fifty one ICU admissions have been reported and 113 cases were adults ≥65 years of age. A total of 110 ICU cases (73%) reported to have at least one underlying condition or comorbidity. Of the 114 ICU cases with known immunization status, 38 (33%) reported not having been vaccinated this season. One hundred and twenty one deaths have been reported, 111 (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.
81	0	18	63	7	88 (14.2%)
109	1	35	73	29	138 (22.2%)
124	1	40	83	28	152 (24.5%)
129	0	44	85	31	160 (25.8%)
60	0	25	35	23	83 (13.4%)
503	2	162	339	118	621
81.0%	0.4%	32.2%	67.4%	19.0%	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 (%)
104	1	54	49	10	114 (6%)
214	1	92	121	48	262 (13%)
1555	3	732	820	136	1691 (82%)
1876	5	879	992	195	2071
91%	0%	47%	53%	9%	100%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 12, 148 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*, which is similar to the number reported the previous week. Of the 148 hospitalizations, 97 (66%) were due to influenza A and 97 (65%) were in patients ≥65 years of age.
Since the start of the 2014-15 season, 6,499 hospitalizations have been reported; 6,008 (92.4%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 340 ICU admissions have been reported to date: 54% (n=183) were in adults ≥65 years of age and 32% (n=110) were in adults 20-64 years. A total of 479 deaths have been reported since the start of the season: three children <5 years of age, three children 5-19 years, 40 adults 20-64 years, and 433 adults ≥65 years of age. Adults 65 years of age or older represent 90% 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.

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.
398	2	143	253	34	432 (7%)
266	2	130	134	56	322 (5%)
366	3	220	143	66	432 (7%)
564	4	234	326	63	627 (10%)
4358	2	2024	2332	254	4612 (71%)
56	1	52	3	18	74 (1%)
6008	14	2803	3191	491	6499
92.4%	0.2%	46.7%	53.1%	7.6%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.

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March 27, 2015, 05:08 PM

FluWatch report: March 15 to 21, 2015 (Week 11)

Posted 2015-03-27 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 15 to 21, 2015 (Week 11) (PDF Version - 824 KB - 10 pages)

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Overall Summary

The majority of influenza activity is occurring in the Central and Atlantic provinces.
Influenza B detections continue to increase steadily across Canada while detections of influenza A continues to steadily decrease. This increase in influenza B is expected as influenza B often shows up later in the flu season.
Despite the late-season circulation of influenza B, influenza A(H3N2) remains the most common influenza virus detected this season to date and seniors continue to be affected.
Evidence from the National Microbiology Laboratory (NML) indicates that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 11

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 11, the number of positive influenza tests (958) and the percentage positive for influenza A (5.4%) continued to decline from the previous week (Figure 2). The percentage of positive influenza B tests continued to increase and was 11.5% in week 11. Influenza B detections were greater than influenza A detections in many provinces (BC, AB, SK, MB, QC, PE and NS). To date, 89% of influenza detections have been influenza A, and 99.4% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 33,253 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, accounting for 60% 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 11, detections for all other respiratory viruses remained similar to, or decreased from, the previous week, except those for rhinovirus (Figure 3).
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
10	0	0	10	38	3462	25	2584	853	265
14	0	11	3	78	3662	13	3497	152	609
0	0	0	0	10	1306	0	837	469	108
0	0	0	0	11	1118	0	388	730	72
138	3	46	89	98	10854	39	4561	6254	494
81	0	0	81	318	11289	4	422	10863	2209
38	0	10	28	36	1042	0	164	878	176
14	0	0	14	53	464	0	123	341	180
4	0	4	0	3	120	1	117	2	26
11	0	0	11	3	603	0	53	550	13
310	3	71	236	648	33920	82	12746	21092	4152
32.4%	1.0%	22.9%	76.1%	67.6%	89.1%	0.2%	37.6%	62.2%	10.9%

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
13	0	2	11	33	2059	17	801	1241	267	2326	7.0%
6	1	4	1	30	1757	6	946	805	430	2187	6.6%
18	0	3	15	68	3388	16	1644	1728	592	3980	12.0%
24	0	1	23	114	3803	17	1626	2160	944	4747	14.3%
105	1	16	88	227	18419	12	7143	11264	1471	19890	59.8%
1	0	1	0	0	120	0	99	21	3	123	0.4%
167	2	27	138	472	29546	68	12259	17219	3707	33253	100.0%
26.1%	1.2%	16.2%	82.6%	73.9%	88.9%	0.2%	41.5%	58.3%	11.1%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 1,024 influenza viruses for resistance to oseltamivir and 1,021 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 1,223 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
811	1	809	0	1218	1217 (99.9%)
6	0	5	0	6	6 (100%)
207	0	207	0	NA ^*	NA ^*
1024	1	1021	0	1224	1223

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 414 influenza viruses [174 A(H3N2), 5 A(H1N1) and 235 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=174), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 168 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 971 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 969 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Five A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 235 influenza B viruses characterized, 225 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and seven were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 414

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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased in week 11 to 28.9 consultations per 1,000, which is within expected levels (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

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Influenza Outbreak Surveillance

In week 11, 63 new outbreaks of influenza were reported. The majority of the outbreaks occurred in the Central and Atlantic provinces. Forty-nine outbreaks were reported in long-term care facilities (LTCF), five in hospitals and nine in institutional or community settings (Figure 6). An additional two outbreaks of ILI were reported in schools. Among the outbreaks in which the influenza subtype was known (n=11), ten outbreaks were associated with influenza B (one in a hospital, seven in LTCFs, and two in an institutional or community setting). To date this season, 1,142 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

During week 11, the proportion of prescriptions for antivirals was 119.1 antiviral prescriptions per 100,000 total prescriptions which was similar to the previous week. The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups except seniors decreased in week 11. The rate was highest among seniors at 189.5 per 100,000 total prescriptions and lowest among infants at 50.5 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 11, 14 laboratory-confirmed influenza-associated paediatric (=16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: five cases of influenza A and nine cases of 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, three (21%) were <2 years of age, ten (71%) were 2 to 9 years of age and one (7%) was 10-16 years of age. One ICU admission was reported.
To date this season, 595 hospitalizations have been reported by the IMPACT network, 502 (84%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (163/165) were A(H3N2) (Table 4). To date, 74 cases were admitted to the ICU, of which 39 (53%) were 2 to 9 years of age (Figure 9a). A total of 49 ICU cases reported to have at least one underlying condition or comorbidity. Three 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 11, 28 laboratory-confirmed influenza-associated adult (=16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 11, 20 cases (74%) were in adults over the age of 65 and 18 cases (67%) had influenza B (Figure 8b).
To date this season, 2,009 cases have been reported; 1,852 (92%) with influenza A. The majority of cases (82%) were among adults =65 years of age (Table 5). One hundred and forty nine ICU admissions have been reported and 112 cases were adults =65 years of age. A total of 107 ICU cases (72%) reported to have at least one underlying condition or comorbidity. Of the 114 ICU cases with known immunization status, 37 (32%) reported not having been vaccinated this season. One hundred and seventeen deaths have been reported, 107 (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.
81	0	18	63	6	87 (14.6%)
109	1	35	73	24	133 (22.4%)
122	1	40	81	23	145 (24.4%)
130	0	45	85	25	155 (26.1%)
60	0	25	35	15	75 (12.6%)
502	2	163	337	93	595
84.4%	0.4%	32.5%	67.1%	15.6%	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 (%)
104	1	48	55	8	112 (6%)
214	0	89	125	38	252 (13%)
1531	3	661	867	110	1641 (82%)
1852	4	799	1049	157	2009
92%	0%	43%	57%	8%	100%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 11, 148 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is slightly more than the number reported in week 10 (n=139). Of the 148 hospitalizations, all but 49 were due to influenza A, and 67% were in patients =65 years of age.
Since the start of the 2014-15 season, 6,249 hospitalizations have been reported; 5,877 (95%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (71%) were =65 years of age (Table 6). A total of 321 ICU admissions have been reported to date: 54% (n=172) were in adults =65 years of age and 32% (n=102) were in adults 20-64 years. A total of 462 deaths have been reported since the start of the season: three children <5 years of age, three children 5-19 years, 38 adults 20-64 years, and 418 adults =65 years of age. Adults 65 years of age or older represent 90% 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.

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.
389	2	139	248	28	417 (7%)
259	2	127	130	43	302 (5%)
364	3	218	143	43	407 (7%)
547	4	226	317	52	599 (10%)
4262	2	1958	2302	191	4453 (71%)
56	1	52	3	15	71 (1%)
5877	14	2720	3143	372	6249
94.0%	0.2%	46.3%	53.5%	6.0%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.
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March 20, 2015, 05:04 PM

FluWatch report: March 8 to 14, 2015 (Week 10)

Posted 2015-03-20 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 8 to 14, 2015 (Week 10) (PDF Version - 824 KB - 10 pages)

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Overall Summary

Elevated influenza activity was mostly reported in the Central and Atlantic provinces and in a few regions in the Western provinces. Widespread activity was reported in regions in Quebec and Newfoundland and Labrador.
Influenza B detections continue to increase steadily, particularly in the West, the Prairies and in Quebec and is mainly affecting individuals less than 65 years of age. This week, overall detections for influenza B surpassed that of influenza A. This increase in influenza B is expected as influenza B often shows up later in the flu season.
Despite the late-season circulation of influenza B, influenza A(H3N2) remains the most common influenza virus detected this season to date and seniors continue to be affected.
Evidence from the National Microbiology Laboratory (NML) indicates that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 10

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 10, the number of positive influenza tests (1,010) and the percentage positive for influenza A (6.6%) continued to decline from the previous week (Figure 2). The percentage of positive influenza B tests continued to increase and was 10.0% in week 10. Influenza B detections were greater than influenza A detections in many provinces (BC, AB, SK, MB, QC, PE and NS). To date, 91% of influenza detections have been influenza A, and 99.4% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 32,237 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, accounting for 61% 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 10, detections of all respiratory viruses decreased from the previous week (Figure 3). Since week 04, detections of parainfluenza have been greater than those reported in each of the past three seasons. Weekly detections of hMPV this season have been lower compared to the previous 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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
19	0	18	1	23	3452	25	2584	843	227
8	0	5	3	45	3648	12	3484	152	531
3	0	0	3	11	1304	0	836	468	85
5	0	0	5	6	1118	0	385	733	61
173	3	58	112	82	10684	34	4511	6139	379
98	0	0	98	349	11208	4	422	10782	1891
74	0	12	62	38	1004	0	154	850	140
14	0	0	14	40	450	0	123	327	127
3	0	3	0	10	116	1	113	2	23
6	0	0	6	3	592	0	53	539	10
403	3	96	304	607	33576	76	12665	20835	3474
39.9%	0.7%	23.8%	75.4%	60.1%	90.6%	0.2%	37.7%	62.1%	9.4%

¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
13	0	2	11	26	2033	15	796	1222	226	2259	7.0%
3	0	2	1	32	1738	5	937	796	360	2098	6.5%
8	0	2	6	45	3350	14	1631	1705	500	3850	11.9%
18	0	0	18	122	3741	15	1608	2118	786	4527	14.0%
80	0	4	76	208	18194	11	7064	11119	1192	19386	60.1%
0	0	0	0	0	115	0	97	18	2	117	0.4%
122	0	10	112	433	29171	60	12133	16978	3066	32237	100.0%
22.0%	0.0%	8.2%	91.8%	78.0%	90.5%	0.2%	41.6%	58.2%	9.5%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 946 influenza viruses for resistance to oseltamivir and 943 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 1,144 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
773	1	770	0	1141	1140 (99.9%)
169	0	169	0	4	4 (100%)
4	0	4	0	NA ^*	NA ^*
946	1	943	0	1145	1144

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 373 influenza viruses [152 A(H3N2), 5 A(H1N1) and 216 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=152), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 146 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 913 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 911 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Five A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 216 influenza B viruses characterized, 207 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and six were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 373

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 by WHO.
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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate remained similar to the previous week and was at 49.3 consultations per 1,000, which is within expected levels (Figure 5). The rate was highest among the 0 to 4 years of age group (60.7 consultations per 1,000) and lowest among the 5 to 19 years age group (35.1 consultations per 1,000).

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

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Influenza Outbreak Surveillance

In week 10, 38 new outbreaks of influenza were reported. The majority of the outbreaks occurred in the Central and Atlantic provinces. Thirty-two outbreaks were reported in long-term care facilities (LTCF), and six in institutional or community settings (Figure 6). An additional thirteen outbreaks of ILI were reported in schools. Among the outbreaks in which the influenza subtype was known, one LTCF outbreak was associated with A(H3N2) and five outbreaks were associated with influenza B. To date this season, 1,093 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

During week 10, the proportion of prescriptions for antivirals decreased to 108.4 antiviral prescriptions per 100,000 total prescriptions (from 137.9 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups except infants decreased in week 10. The rate was highest among seniors at 142.9 per 100,000 total prescriptions and lowest among infants at 68.8 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 10, 17 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: four cases of influenza A and 13 cases of 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, five (29%) were <2 years of age, seven (41%) were 2 to 9 years of age and five (30%) were 10-16 years of age. One ICU admission was reported.
To date this season, 579 hospitalizations have been reported by the IMPACT network, 495 (86%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (162/164) were A(H3N2) (Table 4). To date, 72 cases were admitted to the ICU, of which 38 (53%) were 2 to 9 years of age (Figure 9a). A total of 39 ICU cases reported to have at least one underlying condition or comorbidity. Three 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 10, 44 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 10, 32 cases (73%) were in adults over the age of 65 and 25 cases (57%) had influenza B (Figure 8b).
To date this season, 1,961 cases have been reported; 1,832 (93%) with influenza A. The majority of cases (82%) were among adults ≥65 years of age (Table 5). One hundred and forty seven ICU admissions have been reported and 110 cases were adults ≥65 years of age. A total of 105 ICU cases (71%) reported to have at least one underlying condition or comorbidity. Of the 107 ICU cases with known immunization status, 37 (35%) reported not having been vaccinated this season. One hundred and thirteen deaths have been reported, 103 (91%) 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.
79	0	17	62	6	85 (14.7%)
107	1	35	71	23	130 (22.5%)
121	1	40	80	19	140 (24.2%)
128	0	45	83	21	149 (25.7%)
60	0	25	35	15	75 (13.0%)
495	2	162	331	84	579
85.5%	0.4%	32.7%	66.9%	14.5%	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 (%)
103	1	47	55	7	110 (6%)
210	0	88	122	31	241 (12%)
1516	3	643	870	90	1606 (82%)
1832	4	779	1049	129	1961
93%	0%	43%	57%	7%	100%

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 10, 139 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is less than the number reported in week 09 (n=182). Of the 139 hospitalizations, all but 35 were due to influenza A, and 72% were in patients ≥65 years of age. Since the start of the 2014-15 season, 5,998 hospitalizations have been reported; 5,709 (95%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (72%) were ≥65 years of age (Table 6). A total of 302 ICU admissions have been reported to date: 54% (n=164) were in adults ≥65 years of age and 32% (n=96) were in adults 20-64 years. A total of 436 deaths have been reported since the start of the season: three children <5 years of age, three children 5-19 years, 26 adults 20-64 years, and 404 adults ≥65 years of age. Adults 65 years of age or older represent 93% 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.

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.
378	2	137	239	19	397 (7%)
247	2	123	122	35	282 (5%)
353	3	208	142	33	386 (6%)
534	4	221	309	40	574 (10%)
4141	2	1899	2240	151	4292 (72%)
56	1	52	3	11	67 (1%)
5709	14	2640	3055	289	5998
95.2%	0.2%	46.2%	53.5%	4.8%	100.0%

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.

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March 13, 2015, 04:51 PM

FluWatch report: March 1 to 7, 2015 (Week 9)

Posted 2015-03-13 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 1 to 7, 2015 (Week 9) (PDF Version - 913 KB - 10 pages)

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Overall Summary

In week 09, all influenza indicators remained similar to, or declined from the previous week.
Elevated influenza activity was mostly reported in the Central and Atlantic provinces
Influenza B detections continues to increase steadily, particularly in the West, the Prairies and in Quebec. It is mainly affecting individuals less than 64 years of age. This increase in influenza B is expected as influenza B often shows up later in the flu season.
A(H3N2) continues to be the most common influenza virus this season and seniors continue to have the highest number of positive laboratory detections, hospitalizations and deaths.
Evidence from the National Microbiology Laboratory (NML) indicates that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

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 09, no widespread activity was reported. Seventeen regions reported localized activity: AB, ON(7), QC, NB(3), NS(4), and NL. Twenty-seven regions reported sporadic activity: in YK, BC(5), AB(4), SK(2), MB(3), QC(5), NB(3), NS(2), PE and NL. No activity was reported in fourteen regions: NU(3), NT(2), SK, MB(2), NB, NS(3) and NF(2). When compared to the previous week, there was an overall decrease in influenza activity as there were less regions reporting activity and no regions reporting widespread activity.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 9

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 09, the number of positive influenza tests (1,081) and the percentage positive for influenza A (8.6%) continued to decline from the previous week (Figure 2). The percentage of positive influenza B tests continued to increase and was 7.7% in week 09. Influenza B detections were greater than influenza A detections in many provinces (BC, AB, SK, MB, QC and PE). To date, 92% of influenza detections have been influenza A, and 99.4% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 31,623 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 64 years of age, accounting to 63% 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 09, detections of all respiratory viruses decreased from the previous week (Figure 3). Detections of respiratory syncytial virus (RSV) in week 09 were greater than the detections of influenza A with 757 detections (vs 572 detections of influenza A). In recent weeks, weekly detections of adenovirus, coronavirus, rhinovirus and parainfluenza have been greater than those reported in each of the past three seasons. Weekly detections of hMPV this season have been lower compared to the previous 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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

B Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
25	1	16	8	28	3433	25	2566	842	204
19	0	15	4	39	3640	10	3477	153	485
4	0	2	2	12	1300	0	836	464	68
5	0	1	4	12	1113	0	384	729	55
228	5	72	151	44	10490	30	4448	6012	285
181	0	0	181	310	11110	4	422	10684	1542
66	0	14	52	27	930	0	142	788	102
35	0	0	35	27	436	0	123	313	87
2	0	2	0	7	113	1	110	2	13
7	0	0	7	3	586	0	53	533	7
572	6	122	444	509	33151	70	12561	20520	2848
52.9%	1.0%	21.3%	77.6%	47.1%	92.1%	0.2%	37.9%	61.9%	7.9%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
27	1	2	24	25	2020	15	731	1274	196	2216	7.0%
12	0	4	8	28	1734	5	899	830	324	2058	6.5%
32	0	7	25	66	3341	13	1483	1845	449	3790	12.0%
39	0	6	33	113	3721	14	1443	2264	651	4372	13.8%
208	0	26	182	176	18104	11	6618	11475	966	19070	60.3%
0	0	0	0	0	115	0	97	18	2	117	0.4%
318	1	45	272	408	29035	58	11271	17706	2588	31623	100.0%
43.8%	0.3%	14.2%	85.5%	56.2%	91.8%	0.2%	38.8%	61.0%	8.2%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 857 influenza viruses for resistance to oseltamivir and 853 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 1,062 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
705	1	701	0	1059	1058 (99.9%)
4	0	4	0	4	4 (100%)
148	0	148	0	NA ^*	NA ^*
857	1	853	0	1063	1062

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 305 influenza viruses [149 A(H3N2), 3 A(H1N1) and 153 influenza B]. Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=149), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 143 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 893 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 891 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Three A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B:Of the 153 influenza B viruses characterized, 146 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and four were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 305

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 by WHO.
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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased to 50.5 consultations per 1,000, which is above expected levels for week 09 (Figure 5). The rate was highest among the 5 to 19 years of age group (61.3 consultations per 1,000) and lowest among the adults =65 years of age (41.4 consultations per 1,000)

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

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Influenza Outbreak Surveillance

In week 09, 33 new outbreaks of influenza were reported. The majority of the outbreaks occurred in the Central and Atlantic provinces. Twenty-two outbreaks were reported in long-term care facilities (LTCF), six in hospitals and five in institutional or community settings (Figure 6). An additional five outbreaks of ILI were reported in schools. Among the outbreaks in which the influenza subtype was known, three LTCF outbreaks were associated with A(H3N2) and one outbreak was associated with influenza B. To date this season, 1,061 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

During week 09, the proportion of prescriptions for antivirals decreased to 147.3 antiviral prescriptions per 100,000 total prescriptions (from 150.1 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups except infants decreased in week 09. The rate was highest among seniors at 210.1 per 100,000 total prescriptions and lowest among infants at 64.9 per 100,000 total prescriptions.

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 3,000 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

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 09, seventeen laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: six cases of influenza A and eleven cases of 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, five (29%) were <2 years of age, nine (53%) were 2 to 9 years of age and three (17%) were 10-16 years of age. No ICU admissions were reported.
To date this season, 565 hospitalizations have been reported by the IMPACT network, 496 (88%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (159/161) were A(H3N2) (Table 4). To date, 69 cases were admitted to the ICU, of which 36 (52%) were 2 to 9 years of age (Figure 9a). A total of 38 ICU cases reported to have at least one underlying condition or comorbidity. Three 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 09, 63 laboratory-confirmed influenza-associated adult (=16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 09, 46 cases (73%) were in adults over the age of 65 and 43 cases (68%) had influenza A (Figure 8b).
To date this season, 1,898 cases have been reported; 1,801 (95%) with influenza A. The majority of cases (82%) were among adults =65 years of age (Table 5). One hundred and forty ICU admissions have been reported and 107 cases were adults =65 years of age. A total of 99 ICU cases (71%) reported to have at least one underlying condition or comorbidity. Of the 99 ICU cases with known immunization status, 35 (35%) reported not having been vaccinated this season. One hundred and six deaths have been reported, 97 (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.

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.
79	0	16	63	4	83 (14.7%)
109	1	36	72	23	132 (23.4%)
121	1	40	80	15	136 (24.1%)
127	0	44	83	16	143 (25.3%)
60	0	23	37	11	71 (12.6%)
496	2	159	335	69	565
87.8%	0.4%	32.1%	67.5%	12.2%	100.0%

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.
3	0	1	2	0	3 (%)
102	1	45	56	6	108 (6%)
207	0	88	119	24	231 (12%)
1489	3	632	854	67	1556 (82%)
1801	4	766	1031	97	1898
95%	0%	43%	57%	5%	100%

* 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)

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 09, 182 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is less than the number reported in week 08 (n=213). Of the 182 hospitalizations, all but 28 were due to influenza A, and 74% were in patients =65 years of age. Since the start of the 2014-15 season, 5769 hospitalizations have been reported; 5541 (97%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (72%) were =65 years of age (Table 6). A total of 282 ICU admissions have been reported to date: 54% (n=153) were in adults =65 years of age and 31% (n=88) were in adults 20-64 years. A total of 413 deaths have been reported since the start of the season: three children <5 years of age, two children 5-19 years, 24 adults 20-64 years, and 384 adults =65 years of age. Adults 65 years of age or older represent 93% 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.
374	2	136	236	12	386 (7%)
237	2	119	116	31	268 (5%)
346	3	202	141	27	373 (6%)
518	3	216	299	29	547 (9%)
4010	1	1843	2166	118	4128 (72%)
56	1	52	3	11	67 (1%)
5541	12	2568	2961	228	5769
96.0%	0.2%	46.3%	53.4%	4.0%	100.0%

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, 59 new laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus were reported by the World Health Organization. Globally to March 13, 2015, the WHO reported a total of 631 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 221 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)
Influenza A(H5N6): Since the last FluWatch report, no new cases of human infection with avian influenza A (H5N6) virus from China has been reported by the World Health Organization. Globally to March 13, 2015, the WHO has been informed of a total of three cases of avian influenza A (H5N6) virus, including two deaths.
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, 20 new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to March 13, 2015, the WHO has been informed of a total of 1,060 laboratory-confirmed cases of infection with MERS-CoV, including 394 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)
As of March 9, 2015, the CFIA has removed the avian influenza Primary Control Zone PCZ in British Columbia. Permits are no longer required for the movement of birds and bird products in British Columbia. Surveillance by the CFIA has not detected the H5N2 and H5N1 strains of the virus in domestic poultry since February 2, 2015.
CFIA - Notifiable Avian Influenza

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March 6, 2015, 06:35 PM

FluWatch report: February 22 to 28, 2015 (Week 8)

Posted 2015-03-06 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 22 to 28, 2015 (Week 8) (PDF Version - 385 KB - 10 pages)

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Overall Summary

In week 08, all influenza indicators except the influenza-like illness consultation rate remained similar to, or declined from the previous week.
Elevated influenza activity was mostly reported in the Central and Atlantic provinces and in a few regions in the Western provinces.
Influenza B detections continues to increase steadily, particularly in the Prairies and in Quebec. This increase in influenza B is expected as influenza B often shows up later in the flu season.
A(H3N2) continues to be the most common influenza virus this season and seniors continue to have the highest number of positive laboratory detections, hospitalizations and deaths.
Evidence from the National Microbiology Laboratory (NML) indicates that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

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 08, two regions in Quebec reported widespread activity. Twenty-three regions reported localized activity: BC(2), AB(2), MB, ON(7), QC(2), NB(4), NS(3), PE and NL. Twenty-five regions reported sporadic activity: in YK, NU, NT(2), BC(3), AB(3), SK(3), MB(3), QC(2), NB(3), NS(3), and NL. No activity was reported in seven regions: NU, MB, NS(3) and NL(2). Overall when compared to the previous week, there was a decrease in widespread activity. The majority of widespread and localized activity was reported in the Central and Atlantic provinces; however, more regions reported localised activity compared to the previous week.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 8

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 08, the number of positive influenza tests (1,242) and the percentage positive for influenza A (11.1%) continued to decline from the previous week. The percentage of positive influenza B tests continued to increase and was 5.9% in week 08 (Figure 2). Influenza B detections were greater than influenza A detections in QC and AB; accounting for 57% and 63% of influenza detections respectively. To date, 93% of influenza detections have been influenza A, and 99.5% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 30,350 cases. A significantly greater proportion of laboratory detections of influenza have been reported in adults ≥65 years of age (61%) this season (Table 2) compared to the 2013-14 season when only 16.3% of cases were in adults ≥65 years of age.

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 08, detections of all respiratory viruses except parainfluenza and human metapneumovirus (hMPV) decreased from the previous week (Figure 3). Detections of respiratory syncytial virus (RSV) in week 08 were greater than the detections of influenza A with 867 detections (vs 818 detections of influenza A). In recent weeks, weekly detections of adenovirus, coronavirus, rhinovirus and parainfluenza have been greater than those reported in each of the past three seasons. Weekly detections of hMPV this season have been lower compared to the previous 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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

B Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
36	1	28	7	22	3408	24	2550	834	176
23	0	15	8	39	3621	10	3455	156	446
17	0	0	11	6	1293	0	0	1293	51
12	0	3	9	5	1108	0	382	726	43
341	7	113	221	48	10245	25	4357	5863	236
200	0	0	200	260	10929	4	422	10503	1232
145	0	26	119	25	864	0	128	736	43
23	0	0	23	15	401	0	123	278	60
6	0	6	15	0	579	0	53	526	4
15	0	0	15	0	579	0	53	526	4
818	8	191	613	424	32559	64	11578	20917	2329
65.9%	1.0%	23.3%	74.9%	34.1%	93.3%	0.2%	35.6%	64.2%	6.7%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
28	2	3	23	21	1936	12	723	1201	162	2098	6.9%
13	4	4	5	35	1682	5	895	782	269	1951	6.4%
26	0	5	21	60	3251	13	1460	1778	369	3620	11.9%
53	0	9	44	85	3609	13	1428	2168	512	4121	13.6%
245	0	43	202	136	17677	10	6543	11124	766	18443	60.8%
2	0	2	0	0	115	0	97	18	2	117	0.4%
367	6	66	295	337	28270	53	11146	17071	2080	30350	100.0%
52.1%	1.6%	18.0%	80.4%	47.9%	93.1%	0.2%	39.4%	60.4%	6.9%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 764 influenza viruses for resistance to oseltamivir and 759 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 1042 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
651	1	646	0	1038	1037 (99.9%)
3	0	3	0	4	4 (100%)
110	0	110	0	NA ^*	NA ^*
764	1	759	0	1042	1041

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 277 influenza viruses [125 A(H3N2), 3 A(H1N1) and 149 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=125), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 119 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 827 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 825 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012.
Influenza A(H1N1): Three A(H1N1) viruses characterized were antigenically similar to A/California/7/2009.
Influenza B: Of the 149 influenza B viruses characterized, 142 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and four were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 277

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 by WHO.
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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased to 52.0 consultations per 1,000, which is above expected levels for week 08 (Figure 5). The rate was highest among the 5 to 19 years of age group (67.7 consultations per 1,000) and lowest among the adults ≥65 years of age (34.6 consultations per 1,000)

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

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Influenza Outbreak Surveillance

In week 08, 31 new outbreaks of influenza were reported, a decrease from the previous week. The majority of the outbreaks occurred in the Central and Atlantic provinces. Twenty-four outbreaks were reported in long-term care facilities (LTCF) and seven in institutional or community settings (Figure 6). Among the outbreaks in which the influenza subtype was known, two LTCF outbreaks were associated with A(H3N2). To date this season, 1,039 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

During week 08, the proportion of prescriptions for antivirals decreased to 157.8 antiviral prescriptions per 100,000 total prescriptions (from 221.8 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups decreased in week 08. The rate was highest among seniors at 260.3 per 100,000 total prescriptions and lowest among infants at 45.2 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 08, nine laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: four cases of influenza A and five cases of 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, three (44%) were 2 to 9 years of age and one (11%) was 10-16 years of age. One case was admitted to the ICU.
To date this season, 541 hospitalizations have been reported by the IMPACT network, 486 (90%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (157/159) were A(H3N2) (Table 4). To date, 66 cases were admitted to the ICU, of which 36 (55%) were 2 to 9 years of age (Figure 9a). A total of 38 ICU cases reported to have at least one underlying condition or comorbidity. Three 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 08, 67 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 08, 50 cases (75%) were in adults over the age of 65 and 53 cases (79%) had influenza A (Figure 8b).
To date this season, 1,810 cases have been reported; 1,741 (96%) with influenza A. The majority of cases (82%) were among adults ≥65 years of age (Table 5). One hundred and thirty-six ICU admissions have been reported and 103 cases were adults ≥65 years of age. A total of 97 ICU cases (71%) reported to have at least one underlying condition or comorbidity. Of the 94 ICU cases with known immunization status, 33 (35%) reported not having been vaccinated this season. Ninety-three deaths have been reported, 85 (91%) 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.

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.
76	0	16	60	3	79 (14.6%)
107	1	35	77	20	127 (23.5%)
120	1	39	80	12	132 (24.4%)
125	0	44	81	12	137 (25.3%)
58	0	23	35	8	66 (12.2%)
486	2	157	327	55	541
89.8%	0.4%	32.3%	67.3%	10.2%	100.0%

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.
5	0	1	4	0	5(%)
91	1	40	56	4	101(6%)
195	0	79	116	19	214(12%)
1444	3	576	865	46	1490(82%)
1741	4	696	1041	69	1810
96%	0%	40%	60%	4%	100%

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)

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 08, 213 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is less than the number reported in week 07 (n=276).Of the 213 hospitalizations, all but 16 were due to influenza A, and 73% were in patients ≥65 years of age. Since the start of the 2014-15 season, 5,493 hospitalizations have been reported; 5,312 (97%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 274 ICU admissions have been reported to date: 54% (n=149) were in adults ≥65 years of age and 30% (n=83) were in adults 20-64 years. A total of 389 deaths have been reported since the start of the season: three children <5 years of age, one child 5-19 years, 32 adults 20-64 years, and 353 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.
363	2	132	229	8	371 (7%)
218	0	107	111	16	234 (4%)
263	3	133	127	18	281 (5%)
581	5	279	297	35	616 (11%)
3832	1	1765	2066	94	3926 (71%)
55	1	51	3	10	65 (1%)
5312	12	2467	2833	181	5493
96.7%	0.2%	46.4%	53.3%	3.3%	100.0%

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 March 6, 2015, the WHO reported a total of 572 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 204 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)
Influenza A(H5N6): Since the last FluWatch report, no new cases of human infection with avian influenza A (H5N6) virus from China has been reported by the World Health Organization. Globally to March 5, 2015, the WHO has been informed of a total of three cases of avian influenza A (H5N6) virus, including two deaths.
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, 10 new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to March 6, 2015, the WHO has been informed of a total of 1,040 laboratory-confirmed cases of infection with MERS-CoV, including 383 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)
Since the last FluWatch report, no new information has been provided by the CFIA. Further information on the outbreak is provided on the following CFIA website.
CFIA - Notifiable Avian Influenza

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February 27, 2015, 05:54 PM

FluWatch report: February 15 to 21, 2015 (Week 7)

Posted 2015-02-27 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 15 to 21, 2015 (Week 7) (PDF Version - 385 KB - 10 pages)

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Overall Summary

In week 07, all influenza indicators remained similar to, or declined, from the previous week.
Overall, elevated activity was mostly reported in the Central and Atlantic provinces.
For the past few weeks, influenza B detections have been increasing steadily, particularly in the Prairies and in Quebec. In week 07, influenza B detections were greater than influenza A detections in QC and AB. This increase in influenza B is expected as influenza B often shows up later in the flu season.
A(H3N2) continues to be the most common type of influenza affecting Canadians. Seniors continue to have the highest number of positive laboratory detections, hospitalizations and deaths.
Detections of respiratory syncytial virus (RSV) continue to be the second most frequently detected virus after influenza.
Evidence from the National Microbiology Laboratory (NML) does indicate that this year?s vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

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 atFluWatch@phac-aspc.gc.ca
Influenza/ILI Activity (geographic spread)

In week 07, six regions reported widespread activity: in ON(2). QC(2), PEI and NL. Twenty regions reported localized activity: in AB, ON(5), QC(2), NB(6), NS(5) and NL. Twenty-six regions reported sporadic activity: in YK, NU(2), BC(5), AB(4), SK(3), MB(4), QC(2), NB, NS(3), and NL. No activity was reported in four regions: NU, MB, NS and NF. No data was reported from NT. Overall, influenza activity in week 07 was similar to the previous week with elevated activity (widespread and localized) mostly reported in the Central and Atlantic provinces.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 7

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 07, the number of positive influenza tests (1,279) and the percentage positive for influenza A (12.2%) continued to decline from the previous week The percentage of positive influenza B tests continued to increase and was 5.3% in week 07, the highest this season thus far (Figure 2). In week 07, influenza B detections were greater than influenza A detections in QC and AB; accounting for 53% and 60% of influenza detections respectively. When comparing by influenza type, the majority of the influenza A cases (62%) were in the elderly while the majority of the influenza B cases (61%) were >45 years of age. To date, 94% 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 29,741 cases. A significantly greater proportion of laboratory detections of influenza have been reported in adults ≥65 years of age (61%) this season (Table 2) compared to the 2013-14 season when only 16.1% of cases were in adults ≥65 years of age.

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 07, detections of all respiratory viruses decreased from the previous week (Figure 3). Respiratory syncytial virus (RSV) remains the second most frequently detected virus after influenza with 817 detections. Detections of RSV since week 38 have been higher than in the previous season. Weekly detections of human metapneumovirus this season have been lower compared to the previous season.
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2014-2015

B Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
117	4	96	17	26	3163	16	2324	823	119
23	1	16	6	35	3597	9	3436	152	406
7	0	5	2	6	1279	0	821	458	41
16	0	3	13	5	1096	0	379	717	38
372	1	135	236	25	9850	18	4236	5596	183
241	0	0	241	267	10758	4	422	10332	983
54	0	0	54	15	719	0	102	617	50
25	0	0	25	11	378	0	123	255	45
7	0	7	0	0	105	1	102	2	2
27	0	0	27	0	564	0	53	511	4
889	6	262	621	390	31509	48	11998	19463	1871
69.5%	0.7%	29.5%	69.9%	30.5%	94.4%	0.2%	38.1%	61.8%	5.6%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
35	0	5	30	19	1928	10	776	1142	140	2068	7.0%
16	0	5	11	44	1687	1	919	767	249	1936	6.5%
51	0	7	44	65	3234	11	1579	1644	296	3530	11.9%
50	0	9	41	81	3580	14	1560	2006	414	3994	13.4%
319	1	63	255	123	17473	9	6861	10603	625	18098	60.9%
4	0	2	2	0	113	0	95	18	2	115	0.4%
475	1	91	383	332	28015	45	11790	16180	1726	29741	100.0%
58.9%	0.2%	19.2%	80.6%	41.1%	94.2%	0.2%	42.1%	57.8%	5.8%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 659 influenza viruses for resistance to oseltamivir and 656 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 956 influenza A viruses (99.9%) were resistant to amantadine (Table 3).

^* NA - not applicable
565	1	562	0	954	953 (99.9%)
2	0	2	0	3	3 (100%)
92	0	92	0	NA ^*	NA ^*
659	1	656	0	957	956

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 243 influenza viruses [110 A(H3N2), 2 A(H1N1) and 131 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=110), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 104 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 745 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 743 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Two A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 131 influenza B viruses characterized, 124 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and four were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 243

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 by WHO.
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.
The WHO has released the recommended composition of the influenza vaccine for the northern hemisphere for the 2015-2016 season. Trivalent vaccines are recommended to contain 1) an A/California/7/2009 (H1N1)pdm09-like virus 2) an A/Switzerland/9715293/2013 (H3N2)-like virus, and 3) an B/Phuket/3073/2013-like virus(Yamagata lineage). Quadrivalent vaccines are recommended to additionally contain a B/Brisbane/60/2008-like virus (Victoria lineage).

Text equivalent for figure 4Influenza strain characterizations, Canada, 2014-2015, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased to 32.7 consultations per 1,000, which is within expected levels for week 07 (Figure 5). The rate was highest among the 5 to 19 years of age group (83.3 consultations per 1,000) and lowest among the adults ≥65 years of age (18.7 consultations per 1,000).

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

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Influenza Outbreak Surveillance

In week 07, 56 new outbreaks of influenza were reported, a decrease from the previous week. The majority of the outbreaks occurred in the Central and Atlantic provinces. Forty-five outbreaks were reported in long-term care facilities (LTCF), two in hospitals and nine in institutional or community settings (Figure 6). An additional seven outbreaks of ILI were reported in schools. Among the outbreaks in which the influenza subtype was known, three LTCF outbreaks were associated with A(H3N2) and two outbreaks were associated with influenza B. To date this season, 1,015 outbreaks in LTCFs have been reported and the majority of those with known subtypes were attributable to A(H3N2). There has 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

During week 07, the proportion of prescriptions for antivirals decreased to 226.4 antiviral prescriptions per 100,000 total prescriptions (from 299.6 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups decreased in week 07. The rate was highest among seniors at 407.0 per 100,000 total prescriptions and lowest among infants at 105.7 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 07, 24 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: 12 cases of influenza A and 12 cases of influenza B (Figure 8a). Among the reported cases, 11 (46%) were <2 years of age, five (46%) were 2 to 9 years of age and two (8%) was 10-16 years of age. Two cases were admitted to the ICU. To date this season, 530 hospitalizations have been reported by the IMPACT network, 480 (91%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (157/159) were A(H3N2) (Table 4). To date, 65 cases were admitted to the ICU, of which 37 (57%) were 2 to 9 years of age (Figure 9a). Three 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 07, 60 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 07, 48 cases (80%) were in adults over the age of 65 and 48 cases (80%) had influenza A (Figure 8b). To date this season, 1,717 cases have been reported; 1,663 (97%) with influenza A. The majority of cases (83%) were among adults ≥65 years of age (Table 5). One hundred and twenty-nine ICU admissions have been reported and 97 cases were adults ≥65 years of age. A total of 94 ICU cases (73%) reported to have at least one underlying condition or comorbidity. Of the 91 ICU cases with known immunization status, 33 (36%) reported not having been vaccinated this season. Eighty deaths have been reported, 73 (91%) 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.

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.
76	0	17	59	3	79 (14.9%)
105	1	34	70	19	124 (23.4%)
117	1	39	77	11	128 (24.2%)
124	0	44	80	10	134 (25.3%)
58	0	23	35	7	65 (12.3%)
480	2	157	321	50	530
90.6%	0.4%	32.7%	66.9%	9.4%	100.0%

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.
5	0	1	4	0	5(%)
91	1	39	51	3	94(5%)
183	0	75	108	15	198(12%)
1384	3	543	838	36	1420(83%)
1663	4	658	1001	54	1717
97%	0%	40%	60%	3%	100%

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 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)

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 07, 276 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is slightly more than the number reported in week 06 (n=264).Of the 276 hospitalizations, all but 14 were due to influenza A, and 72% were in patients ≥65 years of age. Since the start of the 2014-15 season, 5,204 hospitalizations have been reported; 5,062 (97%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.5% were A(H3N2). The majority of cases (72%) were ≥65 years of age (Table 6). A total of 254 ICU admissions have been reported to date: 55% (140) were in adults ≥65 years of age and 30% (75) were in adults 20-64 years. A total of 364 deaths have been reported since the start of the season: three children <5 years of age, one child 5-19 years, 24 adults 20-64 years, and 336 adults ≥65 years of age. Adults 65 years of age or older represent 93% 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.
353	2	130	221	7	360 (7%)
213	0	105	108	10	223 (4%)
248	2	127	119	14	262 (5%)
549	5	262	282	27	576 (11%)
3645	1	1686	1958	75	3720 (71%)
54	1	50	3	9	63 (1%)
5062	11	2360	2691	142	5204
97.3%	0.2%	46.6%	53.2%	2.7%	100.0%

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, one new laboratory-confirmed case of human infection with avian influenza A(H7N9) virus was reported by the World Health Organization. Globally to February 26, 2015, the WHO reported a total of 572 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 204 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)
Influenza A(H5N6): Since the last FluWatch report, no new cases of human infection with avian influenza A (H5N6) virus from China has been reported by the World Health Organization. Globally to February 26, 2015, the WHO has been informed of a total of three cases of avian influenza A (H5N6) virus, including two deaths.
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, 47 new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to February 26, 2015, the WHO has been informed of a total of 1,030 laboratory-confirmed cases of infection with MERS-CoV, including 381 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)
Since the last FluWatch report, no new information has been provided by the CFIA. Further information on the outbreak is provided on the following CFIA website.
CFIA - Notifiable Avian Influenza
For the latest Travel Health Notice on Avian Influenza (H5N1) visit the following webpage: PHAC ? Travel Health Notice.

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February 20, 2015, 04:04 PM

FluWatch report: February 8 to 14, 2015 (Week 6)

Posted 2015-02-20 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 8 to 14, 2015 (Week 6) (PDF Version - 385 KB - 10 pages)

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Overall Summary

In week 06, all influenza indicators declined from, or remained similar to, the previous week.
Influenza activity in the Central and the Atlantic Provinces continued into week 06 (mainly due to influenza A) while activity in the Western provinces and the Territories declined.
For the past few weeks, influenza B detections have been increasing steadily, particularly in the Prairies and in Quebec.
A(H3N2) continues to be the most common type of influenza affecting Canadians. Seniors continue to have the highest number of positive laboratory detections, hospitalizations and deaths.
Detections of respiratory syncytial virus (RSV) continue to be the second most frequently detected virus after influenza.
Evidence from the National Microbiology Laboratory (NML) does indicate that this year?s vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

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 06, seven regions reported widespread activity: in MB, ON(2). QC(2), PEI and NL. Twenty-one regions reported localized activity: in AB, MB, ON(5), QC(2), NB(7), and NS(5). Twenty-two regions reported sporadic activity: in YK, NT(2), NU, BC(5), AB(4), SK(3), MB(2), QC(2), NS, and NL. No activity was reported for eight regions: NU(2), MB, NS(3) and NF(2). Compared to the previous week, influenza activity declined overall in the Western provinces while influenza activity increased or remained similar in the Central and Atlantic provinces.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 6

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 06, the number of positive influenza tests (1,625) and the percentage positive for influenza A (16.3%) continued to decline from the previous week The percentage of positive influenza B tests continued to increase and was 3.6 % in week 06, the highest this season thus far (Figure 2). In week 06, influenza B accounted for 33%-52% of influenza detections in AB, SK and QC. To date, 95% of influenza detections have been influenza A, and 99.7% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 28,650 cases. A significantly greater proportion of laboratory detections of influenza have been reported in adults ≥65 years of age (61%) this season (Table 2) compared to the 2013-14 season when only 15.6% of cases were in adults ≥65 years of age.

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, 2013-14
In week 06, the number of positive respiratory syncytial virus (RSV) tests decreased to 914 RSV detections and remains the second most frequently detected virus after influenza (Figure 3). In week 06, the percent positive for RSV detections were highest in the Prairies and has surpassed the percent positive for influenza detections in those regions. Detections of RSV since week 38 have been higher than in the previous season. Detections of all other respiratory viruses except human metapneumovirus decreased in week 06. Detections of respiratory viruses (other than RSV) have generally been lower this season compared to the previous season.
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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2013-2014

B Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
174	3	102	69	9	3046	12	2228	806	93
31	0	22	9	33	3573	8	3412	153	371
18	0	13	5	12	1610	0	1092	518	46
32	0	3	29	3	1078	0	369	709	33
535	5	199	331	37	9422	17	4079	5326	152
366	0	0	366	181	10517	4	422	10091	716
89	0	0	89	11	665	0	102	563	35
49	0	0	49	8	353	0	123	230	34
18	0	18	0	1	98	1	95	2	2
17	0	0	17	1	537	0	53	484	4
1,329	8	357	964	296	30899	42	11975	18882	1486
81.8%	0.6%	26.9%	72.5%	18.2%	95.4%	0.1%	38.8%	61.1%	4.6%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
61	0	8	53	18	1875	9	734	1132	119	1994	7.0%
29	0	4	25	38	1654	1	900	753	191	1845	6.4%
58	0	7	51	46	3154	11	1545	1598	222	3376	11.8%
106	0	13	93	58	3480	10	1516	1954	322	3802	13.3%
441	0	57	384	82	17033	8	6663	10362	490	17523	61.2%
4	0	3	1	0	108	0	92	16	2	110	0.4%
699	0	92	607	242	27304	39	11450	15815	1346	28650	100.0%
74.3%	0.0%	13.2%	86.8%	25.7%	95.3%	0.1%	41.9%	57.9%	4.7%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 575 influenza viruses for resistance to oseltamivir and 574 influenza viruses for resistance to zanamivir and all were sensitive to both agents. A total of 856 (99.9%) influenza A viruses were resistant to amantadine (Table 3).

^* NA - not applicable
491	0	490	0	855	854 (99.9%)
2	0	2	0	2	2 (100%)
82	0	82	0	NA ^*	NA ^*
575	0	574	0	857	856

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 194 influenza viruses [95 A(H3N2), 2 A(H1N1) and 97 influenza B].
Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=95), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 89 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 686 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 684 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Two A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 97 influenza B viruses characterized, 90 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and four were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 194

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 by WHO.
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, 2013-2014, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased to 44.5 consultations per 1,000, which is slightly above expected levels for week 06 (Figure 5). The rate was highest among the 5 to 19 years of age group (60.1 consultations per 1,000) and lowest among the adults ≥65 years of age (36.2 consultations per 1,000)

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

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Influenza Outbreak Surveillance

In week 06, 74 new outbreaks of influenza were reported, which is slightly higher than the number of outbreaks reported in the previous week. The majority of the outbreaks occurred in the Central and Atlantic provinces. Sixty outbreaks were reported in long-term care facilities (LTCF), four in hospitals and 10 in institutional or community settings (Figure 6). An additional five outbreaks of ILI were reported in schools. Among the outbreaks in which the influenza subtype was known, four LTCF outbreaks were associated with A(H3N2) and five outbreaks were associated with influenza B. To date this season, 970 outbreaks in LTCFs have been reported and the majority of those with known subtypes were attributable to A(H3N2). There has 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, 2013-2014
Pharmacy Surveillance

During week 06, the proportion of prescriptions for antivirals increased slightly to 298.1 antiviral prescriptions per 100,000 total prescriptions (from 289.9 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in infants and seniors increased in week 06, while the rate in children and adults decreased. The rate was highest amongst seniors at 527.0 per 100,000 total prescriptions and lowest among infants at 135.4 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 06, 14 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: seven cases of influenza A and seven cases of influenza B (Figure 8a). Among the reported cases, six (43%) were <2 years of age, seven (50%) were 2 to 9 years of age and one (7%) was 10-16 years of age. One case was admitted to the ICU. To date this season, 503 hospitalizations have been reported by the IMPACT network, 465 (93%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (142/144) were A(H3N2) (Table 4). To date, 57 cases were admitted to the ICU, of which 35 (61%) were 2 to 9 years of age (Figure 9a). Three 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 06, 56 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 06, 41 cases (73%) were in adults over the age of 65 and 46 cases (82%) had influenza A (Figure 8b). To date this season, 1,628 cases have been reported; 1,590 (98%) with influenza A. The majority of cases (83%) were among adults ≥65 years of age (Table 5). One hundred and nineteen ICU admissions have been reported and 89 cases were adults ≥65 years of age. A total of 86 ICU cases (72%) reported to have at least one underlying condition or comorbidity. Of the 82 ICU cases with known immunization status, 30 (37%) reported not having been vaccinated this season. Seventy-four deaths have been reported, 67 (91%) 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.

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.
74	0	14	60	3	77 (15.3%)
100	1	31	68	14	114 (22.7%)
114	1	37	76	8	122 (24.3%)
118	0	39	79	8	126 (25.0%)
59	0	21	38	5	64 (12.7%)
465	2	142	321	38	503
92.4%	0.4%	30.5%	69.0%	7.6%	100.0%

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.
5	0	1	4	0	5(%)
88	1	37	50	2	90(6%)
179	0	70	109	8	187(11%)
1318	3	511	804	28	1346(83%)
1590	4	619	967	38	1628
98%	0%	39%	61%	2%	100%

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, 2013-14: Paediatric hospitalizations (≤16 years of age, IMPACT)
B) Adult hospitalizations (≥16 year of age, PCIRN-SOS)

Text equivalent for figure 9aPercentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2013-14: 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, 2013-14: Adult hospitalizations (≥16 year of age, PCIRN-SOS)

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 06, 264 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is less than the number reported in week 05 (n=292). Of the 264 hospitalizations, all but two were influenza A, and 77% were in patients ≥65 years of age. Since the start of the 2014-15 season, 4,817 hospitalizations have been reported; 4,715 (98%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.7% were A(H3N2). The majority of cases (72%) were ≥65 years of age (Table 6). A total of 237 ICU admissions have been reported to date: 55% (130) were in adults ≥65 years of age and 30%(73) were in adults 20-64 years. A total of 342 deaths have been reported since the start of the season: four children <5 years of age, one child 5-19 years, 24 adults 20-64 years, and 313 adults ≥65 years of age. Adults 65 years of age or older represent 92% 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.
333	2	126	205	4	337 (7%)
210	1	107	102	13	223 (5%)
288	1	174	113	12	300 (6%)
435	1	188	246	9	444 (9%)
3395	1	1595	1799	57	3452 (72%)
54	1	50	3	7	61 (1%)
4715	7	2240	2468	102	4817
97.9%	0.1%	47.5%	52.3%	2.1%	100.0%

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 February 19, 2015, the WHO reported a total of 571 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 204 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)
Influenza A(H5N6): Since the last FluWatch report, no new cases of human infection with avian influenza A (H5N6) virus from China has been reported by the World Health Organization. Globally to February 19, 2015, the WHO has been informed of a total of three cases of avian influenza A (H5N6) virus, including two deaths.
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, 6 new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to February 19, 2015, the WHO has been informed of a total of 983 laboratory-confirmed cases of infection with MERS-CoV, including 360 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 an outbreak of highly pathogenic avian influenza H5N2 virus in British Columbia's Fraser Valley. To date, there have been 11 commercial infected premises and one non-commercial infected premise with H5N2.
On February 7, 2015 an additional non-commercial farm in the Fraser Valley was confirmed to be infected with highly pathogenic avian influenza H5N1. The CFIA applies the same disease control measures following detections of H5N1 and H5N2. The infected premise is under quarantine, depopulation of the affected birds has been completed and disposal measures are underway. The CFIA has now reduced the size of the restricted zone as progress continues to be made in the control of avian influenza in British Columbia. Avian influenza viruses do not pose risks to food safety when poultry and poultry products are properly handled and cooked. Further information on the outbreak is provided on the following CFIA website.
CFIA - Notifiable Avian Influenza
For the latest Travel Health Notice on Avian Influenza (H5N1) visit the following webpage: PHAC ? Travel Health Notice
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February 13, 2015, 05:00 PM

FluWatch report: February 1 to February 7, 2015 (Week 5)

Posted 2015-02-13 For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 1 to February 7, 2015 (Week 5) (PDF Version - 385 KB- 10 pages)

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Overall Summary

In week 5, all influenza indicators with the exception of ILI and influenza activity continued to decline.
There is ongoing influenza activity in the Western, Central and the Atlantic provinces, predominantly due to influenza A. Influenza B detections have been increasing steadily, particularly in the Prairies and in Quebec.
A(H3N2) continues to be the most common type of influenza affecting Canadians. In both laboratory detections, hospitalizations and deaths and the majority of cases have been among seniors ≥65 years of age.
Detections of respiratory syncytial virus (RSV) continue to be the second most frequently detected virus after influenza. In the Prairies and Quebec, the percent positive for RSV detections surpassed the percent positive for influenza detections in week 05.
A record number of long term care facility (LTCF) outbreaks have been reported this season to date (n=910) and has surpassed the number of LTCF outbreaks reported in each of the past four seasons.
Evidence from the National Microbiology Laboratory (NML) does indicate that this year's vaccine will continue to provide protection against the circulating A(H1N1) and B strains.

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 05, 11 regions reported widespread activity: in BC(2), ON(6), QC, NF and PEI. Eighteen regions reported localized activity: in BC, AB(2), MB, ON, QC(3), NB(4), NS(5), and NL. Twenty-four regions reported sporadic activity: in YK, NU, BC(2), AB(3), SK(3), MB(4), QC(2), NB(2), NS(4), and NF(2). Compared to the previous week, the number of regions reporting widespread activity in week 05 increased. However the overall number of regions reporting elevated activity (widespread and localized) in week 05 declined from the previous week.

Figure 1. Map of overall influenza/ILI activity level by province and territory, Canada, Week 5

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

The number of positive influenza tests decreased from 2,409 in week 04 to 1,729 in week 05. The percentage of positive influenza A tests decreased from 23.1% to 19.5%. The percentage of positive influenza B tests have been increasing for the past few weeks to 2.2% in week 05, the highest this season thus far (Figure 2). The proportion of influenza B detections were highest in the Prairies and Quebec in week 05 (influenza B accounted for 15%-36% of all influenza detections). To date, 96% of influenza detections have been influenza A, and 99.7% of those subtyped have been A(H3N2) (Table 1). To date this season, detailed information on age and type/subtype has been received for 27,061 cases. A significantly greater proportion of laboratory detections of influenza have been reported in adults ≥65 years of age (62%) this season (Table 2) compared to the 2013-14 season when only 15.6% of cases were in adults ≥65 years of age.

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, 2013-14
In week 05, the number of positive respiratory syncytial virus (RSV) tests decreased to 980 RSV detections and remains the second most frequently detected virus after influenza (Figure 3). In week 05, the percent positive for RSV detections in the Prairies and Quebec surpassed the percent positive for influenza detections in those regions. Detections of RSV since week 38 have been higher than in the previous season. Detections of all other respiratory viruses except adenovirus decreased in week 05. Detections of respiratory viruses (other than RSV) have generally been lower this season compared to the previous season. 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

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RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2013-2014

B Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage 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.
172	1	59	112	13	2872	9	2136	737	84
52	1	38	13	29	3476	5	3325	146	299
18	0	10	8	5	1238	0	763	475	20
35	0	9	26	1046	1046	0	366	680	30
610	2	259	349	13	8429	12	3872	4545	106
431	1	0	430	92	10151	4	422	9725	535
150	0	36	114	7	576	0	102	474	24
47	0	0	47	7	304	0	123	181	26
20	0	20	0	0	80	1	77	2	1
22	0	0	22	0	520	0	53	467	3
1,557	5	431	1,121	172	28692	31	11229	17432	1128
90.1%	0.3%	27.7%	72.0%	9.9%	96.2%	0.1%	39.1%	60.8%	3.8%

Total	Total
¹Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Cumulative data includes updates to previous weeks. ²Percentage of tests positive for sub-types of influenza A are a percentage of all influenza A detections. ³Table 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.
72	0	6	66	12	1748	7	681	1060	99	1847	6.8%
36	0	6	30	26	1586	1	850	735	148	1734	6.4%
104	1	12	91	23	3002	9	1453	1540	171	3173	11.7%
105	1	16	88	33	3272	6	1403	1863	259	3531	13.0%
502	0	87	415	44	16267	7	6329	9931	404	16671	61.6%
10	0	8	2	0	103	0	87	16	2	105	0.4%
829	2	135	692	138	25978	30	10803	15145	1083	27061	100.0%
85.7%	0.2%	16.3%	83.5%	14.3%	96.0%	0.1%	41.6%	58.3%	4.0%

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Antiviral Resistance

During the 2014-2015 influenza season, the NML has tested 503 influenza viruses for resistance to oseltamivir and 502 influenza viruses for resistance to zanamivir and all were sensitive to both agents. A total of 783 (99.8%) influenza A viruses were resistant to amantadine (Table 3).

^* NA - not applicable
428	0	428	0	782	781 (99.9%)
2	0	2	0	2	2 (100%)
73	0	72	0	NA ^*	NA ^*
503	0	502	0	784	783

Influenza Strain Characterizations

During the 2014-2015 influenza season, the National Microbiology Laboratory (NML) has characterized 172 influenza viruses [81 A(H3N2), 2 A(H1N1) and 89 influenza B]. Influenza A (H3N2): When tested by hemagglutination inhibition (HI) assay (n=81), one virus was antigenically similar to A/Texas/50/2012, five showed reduced titers to A/Texas/50/2012 and 75 were antigenically similar to A/Switzerland/9715293/2013, which is the influenza A(H3N2) component recommended for the 2015 Southern Hemisphere influenza vaccine. Additionally, 619 A(H3N2) viruses were unable to be tested by HI assay; however, sequence analysis showed that 617 belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Influenza A(H1N1): Two A(H1N1) viruses characterized were antigenically similar to A/California/7/2009. Influenza B: Of the 89 influenza B viruses characterized, 82 viruses were antigenically similar to B/Massachusetts/2/2012, three viruses showed reduced titers against B/Massachusetts/2/2012, and four were B/Brisbane/60/2008-like (Figure 4).

Figure 4. Influenza strain characterizations, Canada, 2014-2015, N = 172

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 by WHO.
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, 2013-2014, N =3
Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased to 55.0 consultations per 1,000, which is slightly above expected levels for week 05 (Figure 5). The rate were highest among the 5 to 19 years of age group (64.9 consultations per 1,000) and lowest among the adults ≥65 years of age (33.9 consultations per 1,000)

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

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Influenza Outbreak Surveillance

In week 05, 71 new outbreaks of influenza were reported, which is lower than the number of outbreaks reported in the previous week. Fifty-one outbreaks were reported in long-term care facilities (LTCF), 7 in hospitals and 13 in institutional or community settings (Figure 6). An additional 8 outbreaks of ILI were reported in schools. Among the outbreaks in which the influenza subtype was known, five LTCF outbreaks were associated with A(H3N2). To date this season, 910 outbreaks in LTCFs have been reported and the majority of those with known subtypes were attributable to A(H3N2). There has 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, 2013-2014
Pharmacy Surveillance

During week 05, the proportion of prescriptions for antivirals decreased to 290.2 antiviral prescriptions per 100,000 total prescriptions (down from 391.1 per 100,000). The rate for antivirals since week 48 has been higher than the previous three seasons (Figure 7). The rate in all age groups decreased in week 05. The rate was highest amongst seniors at 650.0 per 100,000 total prescriptions and lowest among infants at 91.9 per 100,000 total prescriptions.

Figure 7. Proportion of prescription sales for influenza antivirals by age-group and week, Canada, 2014-15

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Sentinel Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 05, 16 laboratory-confirmed influenza-associated paediatric (=16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: 12 cases of influenza A and four cases of influenza B (Figure 8a). Among the reported cases, 6 (38%) were <2 years of age, 9 (56%) were 2 to 9 years of age and one (6%) was 10-16 years of age. One case was admitted to the ICU. To date this season, 489 hospitalizations have been reported by the IMPACT network, 458 (94%) of which were cases of influenza A. Among cases for which the influenza A subtype was reported, 99% (142/144) were A(H3N2) (Table 4). To date, 56 cases were admitted to the ICU, of which 34 (61%) were 2 to 9 years of age (Figure 9a). Three 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 05, 89 laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Among the cases in week 05, 71 cases (80%) were in adults over the age of 65 and 84 cases (94%) had influenza A (Figure 8b). To date this season, 1,532 cases have been reported; 1,505 (98%) with influenza A. The majority of cases (83%) were among adults ≥65 years of age (Table 5). One hundred and five ICU admissions have been reported and 78 cases were adults ≥65 years of age. A total of 81 ICU cases reported to have at least one underlying condition or comorbidity. Of the 72 ICU cases with known immunization status, 24 (33%) reported not having been vaccinated this season. Sixty-six deaths have been reported, 59 (89%) 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.

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.
72	0	14	58	3	75 (15.3%)
98	1	31	66	13	111 (22.7%)
112	1	37	74	4	116 (23.7%)
117	0	39	78	7	124 (25.4%)
59	0	21	38	4	63 (12.9%)
458	2	142	314	31	489
93.7%	0.4%	31.0%	68.6%	6.3%	100.0%

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.
4	0	1	3	0	4(%)
82	1	34	47	2	84(5%)
167	0	68	99	3	170(11%)
1252	3	476	773	22	1274(83%)
1505	4	579	922	27	1532
98%	0%	38%	61%	2%	100%

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 9bPercentage of hospitalizations, ICU admissions and deaths with influenza reported by age-group, Canada, 2013-14: Adult hospitalizations (≥16 year of age, PCIRN-SOS)

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Provincial/Territorial Influenza Hospitalizations and Deaths

In week 05, 292 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories* which is less than the number reported in week 04 (n=345).Of the 292 hospitalizations, all but four were influenza A, and 73% were in patients ≥65 years of age. Since the start of the 2014-15 season, 4,458 hospitalizations have been reported; 4,368 (98%) with influenza A. Among cases for which the subtype of influenza A was reported, 99.7% (2110/2117) were A(H3N2). The majority of cases (71%) were ≥65 years of age (Table 6). A total of 189 ICU admissions have been reported to date, all with influenza A: 65% (122) were in adults ≥65 years of age and 35%(67) were in adults 20-64 years. A total of 307 deaths have been reported since the start of the season: four children <5 years of age, two children 5-19 years, 21 adults 20-64 years, and 280 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.
313	2	121	190	4	317 (7%)
197	0	100	97	7	204 (5%)
218	1	117	100	10	228 (5%)
461	2	231	228	15	476 (11%)
3125	1	1490	1634	49	3174 (71%)
54	1	51	2	6	60 (1%)
4368	7	2110	2251	91	4459
98.0%	0.2%	48.3%	51.5%	2.0%	100.0%

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, 83 new laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus were reported by the World Health Organization. Globally to February 12, 2015, the WHO reported a total of 571 laboratory-confirmed human cases with avian influenza A(H7N9) virus, including 204 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)
Influenza A(H5N6): Since the last FluWatch report, one new case of human infection with avian influenza A (H5N6) virus from China has been reported by the World Health Organization. Globally to February 12, 2015, the WHO has been informed of a total of three cases of avian influenza A (H5N6) virus, including two deaths.
Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
Since the last FluWatch report, 12 new laboratory-confirmed cases of MERS-CoV have been reported by the World Health Organization. Globally, from September 2012 to February 12, 2015, the WHO has been informed of a total of 977 laboratory-confirmed cases of infection with MERS-CoV, including 359 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 an outbreak of highly pathogenic avian influenza H5N2 virus in British Columbia's Fraser Valley. To date, there have been 11 commercial infected premises and one non-commercial infected premise with H5N2. On February 7, 2015 an additional non-commercial farm in the Fraser Valley was confirmed to be infected with highly pathogenic avian influenza H5N1. This is the first time the H5N1 strain of the virus has been detected during the current avian influenza outbreak. The CFIA applies the same disease control measures following detections of H5N1 and H5N2. The infected premise is under quarantine, depopulation of the affected birds has been completed and disposal measures are underway. Avian influenza viruses do not pose risks to food safety when poultry and poultry products are properly handled and cooked. Further information on the outbreak is provided on the following CFIA website.
CFIA - Notifiable Avian Influenza
For the latest Travel Health Notice on Avian Influenza (H5N1) visit the following webpage: PHAC - Travel Health Notice.

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Canada FluWatch Weekly Reports 2014-2015 Season Week 20

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