Re: Canada FluWatch Weekly Reports 2012-2013 Season Week 18
FluWatch report: April 28 to May 4, 2013 (Week 18)
Posted 2013-05-10For readers interested in the <ABBR title="Portable Document Format">PDF</ABBR> version, the document is available for downloading or viewing:
<A title="Flu Watch (Version PDF, 113 KB - 6 pages)" href="http://www.phac-aspc.gc.ca/fluwatch/12-13/w18_13/pdf/fw2013-18-eng.pdf">FluWatch report: April 28 to May 4, 2013 (Week 18) (<ABBR title="Portable Document Format">PDF</ABBR> Version - 113 <ABBR title=Kilobytes>KB</ABBR> - 8 pages)
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Overall Summary
In week 18, seven regions [AB(1), ON(4), QC(1) and NB(1)] reported localized activity and 25 regions reported sporadic activity. The number of regions reporting widespread or localized activity decreased compared to the previous week (Figures 1 and 2). Six new influenza outbreaks were reported: five in long-term-care facilities and one in a school (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 18
Note: Influenza 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 (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions<SUP title="sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in">?</SUP> reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N<SUP>*</SUP>=58)
?sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012
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Influenza and Other Respiratory Virus Detections
The overall percentage of positive influenza tests decreased slightly compared to recent weeks, from 11.2 in week 17 to 10.0% in week 18. Detections of influenza B decreased for the second consecutive week, and represented 86.4% of total positive influenza detections in week 18 (Figure 4). Among the influenza viruses detected in week 18 (n=301), 13.6% were positive for influenza A viruses [of which 48.8% were A(H1N1)pdm09, 9.8% were A(H3), and 41.5% were A(unsubtyped)] (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 86.5% influenza A [34.5% A(H3), 4.6% A(H1N1)pdm09 and 61.0% A(unsubtyped)] and 13.5% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 23,888 cases to date this season (Table 2). The proportion of cases by age group is as follows: 14.1% <5 years; 9.9% between 5-19 years; 15.7% between 20-44 years; 17.0% between 45-64 years of age; 43.2% ≥65 years.
The percentage of positive tests for rhinovirus increased from 12.5% in week 17 to 14.1% in week 18, and has been slowly increasing since week 01. The percentage of positive tests for parainfluenza (5.4%) was stable since week 16, but has been increasing gradually over the past 10 weeks. The percentage of tests positive for respiratory syncytial virus (RSV) (4.5%) continued its decline from a peak in week 08. The percentage of positive tests for human metapneumovirus (hMPV) (5.0%) has been stable since week 16, and the percentage of positive tests for coronavirus (0.8%) has been decreasing slowly since week 04 (Figure 5)<SUP>*</SUP>.
* For more details, see the weekly Respiratory Virus Detections in Canada Report.
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION class=alignCenter>Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2012-2013
</CAPTION><THEAD><TR class=bg-colour-yellow><TH id=ar1 rowSpan=3>Reporting provinces</TH><TH id=ac1 colSpan=6>Weekly
(April 28 to May 4, 2013)
</TH><TH id=ac9 colSpan=6>Cumulative
(August 26, 2012 to May 4, 2013)
</TH></TR><TR class=bg-colour-yellow><TH id=ac2 colSpan=5 headers=ac1>Influenza A</TH><TH id=ac8 headers=ac1>Influenza
B
</TH><TH id=ac10 colSpan=5 headers=ac9>Influenza A</TH><TH id=ac16 headers=ac9>Influenza
B
</TH></TR><TR class=bg-colour-yellow><TH id=ac3 headers=ac2>A Total</TH><TH id=ac4 headers=ac2>A(H1)</TH><TH id=ac5 headers=ac2>A(H3)</TH><TH id=ac6 headers=ac2>Pand H1N1</TH><TH id=ac7 class=noWrap headers=ac2>A
( <ABBR title=unsubtyped>Un S</ABBR>)Table 1 note*
</TH><TH headers="ac1 ac8">Total</TH><TH id=ac11 headers=ac10>A Total</TH><TH id=ac12 headers=ac10>A(H1)</TH><TH id=ac13 headers=ac10>A(H3)</TH><TH id=ac14 headers=ac10>Pand H1N1</TH><TH id=ac15 class=noWrap headers=ac10>A
(Un S) Table 1 note*
</TH><TH headers=ac16>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=13>* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals. </TD></TR></TFOOT><TBODY><TR><TH id=ar2 class=bg-colour-yellow headers=ar1><ABBR title="British Columbia ">BC</ABBR></TH><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac3">3</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac5">1</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac6">2</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar2 ac1 ac8">11</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac11">1907</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac13">1450</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac14">218</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac15">239</TD><TD class=alignRight headers="ar1 ar2 ac9 ac16">397</TD></TR><TR><TH id=ar3 class=bg-colour-yellow headers=ar1><ABBR title=Alberta>AB</ABBR></TH><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac3">7</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac5">2</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac6">4</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac7">1</TD><TD class=alignRight headers="ar1 ar3 ac1 ac8">40</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac11">2347</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac13">1766</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac14">437</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac15">144</TD><TD class=alignRight headers="ar1 ar3 ac9 ac16">748</TD></TR><TR><TH id=ar4 class=bg-colour-yellow headers=ar1><ABBR title=Saskatchewan>SK</ABBR></TH><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac3">2</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac7">2</TD><TD class=alignRight headers="ar1 ar4 ac1 ac8">27</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac11">836</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac13">476</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac14">73</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac15">287</TD><TD class=alignRight headers="ar1 ar4 ac9 ac16">285</TD></TR><TR><TH id=ar5 class=bg-colour-yellow headers=ar1><ABBR title=Manitoba>MB</ABBR></TH><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac3">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac8">2</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac11">657</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac13">78</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac14">10</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac15">569</TD><TD class=alignRight headers="ar1 ar5 ac9 ac16">84</TD></TR><TR><TH id=ar6 class=bg-colour-yellow headers=ar1><ABBR title=Ontario>ON</ABBR></TH><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac3">7</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac5">1</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac6">4</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac7">2</TD><TD class=alignRight headers="ar1 ar6 ac1 ac8">57</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac11">8248</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac13">3778</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac14">369</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac15">4101</TD><TD class=alignRight headers="ar1 ar6 ac9 ac16">843</TD></TR><TR><TH id=ar7 class=bg-colour-yellow headers=ar1><ABBR title=Quebec>QC</ABBR>
</TH><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac3">12</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac6">2</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac7">10</TD><TD class=alignRight headers="ar1 ar7 ac1 ac8">109</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac11">9797</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac13">546</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac14">35</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac15">9216</TD><TD class=alignRight headers="ar1 ar7 ac9 ac16">1768</TD></TR><TR><TH id=ar8 class=bg-colour-yellow headers=ar1><ABBR title="New Brunswick">NB</ABBR>
</TH><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac3">6</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac6">6</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar8 ac1 ac8">13</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac11">1859</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac13">771</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac14">71</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac15">1017</TD><TD class=alignRight headers="ar1 ar8 ac9 ac16">60</TD></TR><TR><TH id=ar9 class=bg-colour-yellow headers=ar1><ABBR title="Nova Scotia ">NS</ABBR>
</TH><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac3">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac8">1</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac11">388</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac13">165</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac14">8</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac15">215</TD><TD class=alignRight headers="ar1 ar9 ac9 ac16">7</TD></TR><TR><TH id=ar10 class=bg-colour-yellow headers=ar1><ABBR title="Prince Edward Island ">PE</ABBR>
</TH><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac3">2</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac6">2</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar10 ac1 ac8">0</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac11">116</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac13">76</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac14">9</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac15">31</TD><TD class=alignRight headers="ar1 ar10 ac9 ac16">1</TD></TR><TR><TH id=ar11 class=bg-colour-yellow headers=ar1><ABBR title="Newfoundland/Labrador ">NL</ABBR>
</TH><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac3">2</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac7">2</TD><TD class=alignRight headers="ar1 ar11 ac1 ac8">0</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac11">717</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac13">152</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac14">0</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac15">565</TD><TD class=alignRight headers="ar1 ar11 ac9 ac16">16</TD></TR><TR><TH id=ar12 class=bg-colour-yellow headers=ar1>Canada</TH><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac3">41</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac5">4</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac6">20</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac7">17</TD><TD class=alignRight headers="ar1 ar12 ac1 ac8">260</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac11">26872</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac13">9258</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac14">1230</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac15">16384</TD><TD class=alignRight headers="ar1 ar12 ac9 ac16">4209</TD></TR></TBODY></TABLE>
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2012-2013 Table 2 note*
</CAPTION><THEAD><TR class=bg-colour-yellow><TH id=br1 rowSpan=3>Age groups</TH><TH id=bc1 colSpan=5>Weekly
(April 28 to May 4, 2013)
</TH><TH id=bc8 colSpan=5>Cumulative
(August 26, 2012 to May 4, 2013)
</TH></TR><TR class=bg-colour-yellow><TH id=bc2 colSpan=4 headers=bc1>Influenza A</TH><TH id=bc7 headers=bc1>B</TH><TH id=bc9 colSpan=4 headers=bc8>Influenza A</TH><TH id=bc14 headers=bc8>B</TH></TR><TR class=bg-colour-yellow><TH id=bc3 headers=bc2>A Total</TH><TH id=bc4 headers=bc2>Pandemic H1N1</TH><TH id=bc5 headers=bc2>A/H3N2</TH><TH id=bc6 headers=bc2>A unsubtyped</TH><TH headers="bc1 bc7">Total</TH><TH id=bc10 headers=bc9>A Total</TH><TH id=bc11 headers=bc9>Pandemic H1N1</TH><TH id=bc12 headers=bc9>A/H3N2</TH><TH id=bc13 headers=bc9>A unsubtyped</TH><TH headers=bc14>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=11>* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively. </TD></TR></TFOOT><TBODY><TR><TH id=br2 headers=br1><5</TH><TD class=alignRight>5</TD><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>32</TD><TD class=alignRight>2674</TD><TD class=alignRight>214</TD><TD class=alignRight>861</TD><TD class=alignRight>1599</TD><TD class=alignRight>706</TD></TR><TR><TH id=br3 headers=br1>5-19</TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>34</TD><TD class=alignRight>1455</TD><TD class=alignRight>66</TD><TD class=alignRight>639</TD><TD class=alignRight>750</TD><TD class=alignRight>908</TD></TR><TR><TH id=br4 headers=br1>20-44</TH><TD class=alignRight>4</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>23</TD><TD class=alignRight>3170</TD><TD class=alignRight>339</TD><TD class=alignRight>1217</TD><TD class=alignRight>1614</TD><TD class=alignRight>586</TD></TR><TR><TH id=br5 headers=br1>45-64</TH><TD class=alignRight>4</TD><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>2</TD><TD class=alignRight>27</TD><TD class=alignRight>3463</TD><TD class=alignRight>312</TD><TD class=alignRight>1233</TD><TD class=alignRight>1918</TD><TD class=alignRight>597</TD></TR><TR><TH id=br6 headers=br1>65+</TH><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>2</TD><TD class=alignRight>45</TD><TD class=alignRight>9611</TD><TD class=alignRight>132</TD><TD class=alignRight>3713</TD><TD class=alignRight>5766</TD><TD class=alignRight>718</TD></TR><TR><TH id=br7 headers=br1>Unknown</TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>166</TD><TD class=alignRight>20</TD><TD class=alignRight>144</TD><TD class=alignRight>2</TD><TD class=alignRight>1</TD></TR><TR><TH id=br8 headers=br1>Total</TH><TD class=alignRight>15</TD><TD class=alignRight>5</TD><TD class=alignRight>0</TD><TD class=alignRight>10</TD><TD class=alignRight>161</TD><TD class=alignRight>20539</TD><TD class=alignRight>1083</TD><TD class=alignRight>7807</TD><TD class=alignRight>11649</TD><TD class=alignRight>3516</TD></TR></TBODY></TABLE>
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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013
Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013
Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012
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Influenza strain characterizations
During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 1221 influenza viruses. The 600 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 193 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 338 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 90 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N =1221
Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012
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Antiviral resistance
During the 2012-13 season, NML has tested 1149 influenza viruses for resistance to oseltamivir, and 1145 influenza viruses for resistance to zanamivir. Among these, one A(H3N2) virus was resistant to oseltamivir and zanamivir. A total of 1180 influenza A viruses were tested for amantadine resistance and all but one were resistant (Table 3).
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013</CAPTION><THEAD><TR class=bg-colour-yellow><TH id=cr1 rowSpan=2>Virus type and subtype</TH><TH id=cc1 colSpan=2>Oseltamivir</TH><TH id=cc4 colSpan=2>Zanamivir</TH><TH id=cc7 colSpan=2>Amantadine</TH></TR><TR class=bg-colour-yellow><TH id=cc2 headers=cc1># tested</TH><TH id=cc3 headers=cc1># resistant (%)</TH><TH id=cc5 headers=cc4># tested</TH><TH id=cc6 headers=cc4># resistant (%)</TH><TH id=cc8 headers=cc7># tested</TH><TH id=cc9 headers=cc7># resistant (%)</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=7><SUP>*</SUP> NA - not applicable</TD></TR></TFOOT><TBODY><TR><TH id=cr2 class="alignLeft bg-colour-blue" headers=cr1>A (H3N2)</TH><TD class=alignRight headers="cr2 cc2">572</TD><TD class=alignRight headers="cr2 cc3">1 (0.2%)</TD><TD class=alignRight headers="cr2 cc5">573</TD><TD class=alignRight headers="cr2 cc6">1 (0.2%)</TD><TD class=alignRight headers="cr2 cc8">955</TD><TD class=alignRight headers="cr2 cc9">954 (99.9%)</TD></TR><TR><TH id=cr3 class="alignLeft bg-colour-blue" headers=cr1>A (H1N1)</TH><TD class=alignRight headers="cr3 cc2">194</TD><TD class=alignRight headers="cr3 cc3">0</TD><TD class=alignRight headers="cr3 cc5">190</TD><TD class=alignRight headers="cr3 cc6">0</TD><TD class=alignRight headers="cr3 cc8">225</TD><TD class=alignRight headers="cr3 cc9">225 (100%)</TD></TR><TR><TH id=cr4 class="alignLeft bg-colour-blue" headers=cr1>B</TH><TD class=alignRight headers="cr4 cc2">383</TD><TD class=alignRight headers="cr4 cc3">0</TD><TD class=alignRight headers="cr4 cc5">382</TD><TD class=alignRight headers="cr4 cc6">0</TD><TD class=alignRight headers="cr4 cc8">NA <SUP>*</SUP></TD><TD class=alignRight headers="cr4 cc9">NA <SUP>*</SUP></TD></TR><TR><TH id=cr5 class="alignLeft bg-colour-blue" headers=cr1>TOTAL</TH><TD class=alignRight headers="cr5 cc2">1149</TD><TD class=alignRight headers="cr5 cc3">1 (0.1%)</TD><TD class=alignRight headers="cr5 cc5">1145</TD><TD class=alignRight headers="cr5 cc6">1 (0.1%)</TD><TD class=alignRight headers="cr5 cc8">1180</TD><TD class=alignRight headers="cr5 cc9">1179 (99.9%)</TD></TR></TBODY></TABLE>
Influenza-like Illness (ILI) Consultation Rate
The national influenza-like-illness (ILI) consultation rate increased from 14.5 ILI consultations per 1,000 patient visits in week 17 to 17.6 / 1,000 in week 18, and is above the expected range (Figure 7). In week 18, the highest consultation rate was observed in children under 5 years of age (63.2/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)
Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
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Severe Respiratory Illness Surveillance
Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 18, 16 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 15 in week 17. All of the cases reported in week 18 were identified with influenza B. The age distribution is as follows: 3 (18.8%) between 0-5 months, 2 (12.5%) between 6-23 months, 4 (25.0%) 2-4 years of age, and 7 (43.8%) 5-9 years of age. Two cases were admitted to an intensive care unit (ICU) during week 18, one child 2-4 years of age and one 5-9 years of age; both with influenza B. No deaths were reported in week 18.
Since the start of the 2012-13 season, a total of 855 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 621 (72.6%) with influenza A [of which 120 (19.3%) were A(H3N2), 25 (4.0%) were A(H1N1)pdm09 and the remaining 476 were A(unsubtyped); and 234 (27.4%) with influenza B. The distribution of cases by age group is as follows: 157 (18.4%) <6 months of age; 199 (23.3%) age 6-23 months; 244 (28.5%) age 2-4 years; 183 (21.4%) age 5-9 years; and 72 (8.4%) age 10-16 years. Ninety-two (10.8%) of the 855 cases were admitted to the ICU. Of the 70 ICU admissions with available data, 60 (85.7%) cases had at least one co-morbidity. One death has been reported to date this season in a child 6-23 months of age with an underlying condition, with influenza B.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Adult Influenza Hospitalizations and Deaths (PCIRN)
PCIRN-SOS surveillance has concluded for the 2012-13 influenza season. In week 18, eight 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. All eight hospitalizations were cases of influenza B; three cases were ≥65 years of age, two were 45-64 years, two were 20-44 years and one was <20 years of age. Two ICU admissions were reported, both cases with influenza B; one ≥65 years of age and one 45-64 years of age. No deaths were reported in week 18. Only nine of the 17 PCIRN centres reported data in week 18. A summary of final data will be included in the 2012-13 FluWatch annual report.
From November 4, 2012 to May 4, 2013, 1,779 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,620 (91.1%) with influenza A [of which 310 were A(H3N2), 19 were A(H1N1)pdm09, and 1,291 were A(unsubtyped)]; 113 (6.4%) with influenza B, and the type has not been reported for 46 cases. The age distribution of hospitalizations is as follows: 1,212 (68.1%) were ≥65 years of age, 364 (20.5%) were 45-64 years, 194 (10.9%) were 20-44 years, and 9 (0.5%) were <20 years of age. ICU admission was required for 214 hospitalizations; the majority of which were adults ≥65 years of age (124; 57.9%). Of the ICU admissions, 90 (42.1%) had at least one co-morbidity, five (2.3%) had no co-morbidities, and 119 had no information to date. A total of 115 deaths have been reported: 26 with influenza A(H3N2), one with A(H1N1)pdm09, 82 with A(unsubtyped), five with influenza B, and one untyped. More than 85% of the deaths (98/115) were in adults ≥65 years of age, 14 (12.2%) were adults 45-64 years of age, and 3 (2.6%) were 20-44 years of age. Fifty-two (45.2%) deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining cases.
Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System<SUP>*</SUP>)
In week 18, 69 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories<SUP>*</SUP>. The majority of cases were influenza A (56.5%). The highest proportion of hospitalisations were in adults ≥65 years of age (40.6%), followed by children 0-4 years of age (21.7%). Of the 17 cases with available data, six cases were admitted to the ICU, three with influenza A(H1N1)pdm09 and three with influenza B; four were ≥65 years of age, one was 45-64 years of age, and one was 5-14 years of age. Two deaths were reported in week 18, both adults ≥65 years of age with influenza A.
To date this season, 4,733 influenza-associated hospitalizations have been reported, of which 89.1% have been influenza A. Of those subtyped (48.8%), influenza A(H3) was the predominant influenza strain. The cumulative proportion of hospitalizations with influenza B continues to increase (10.9% in week 18). Age information was available for 4,730 cases, and the age distribution is as follows: 2,518 (53.2%) were ≥65 years of age; 789 (16.7%) were 45-64 years of age; 429 (9.1%) were 20-44 years of age; 40 (0.8%) were 15-19 years of age; 228 (4.8%) were 5-14 years; and 726 (15.3%) were 0-4 years of age. Of the 1,293 cases with available data, there have been 204 hospitalisations for which admission to an ICU was required; the highest proportions have been in adults 45-64 years of age, followed by adults ≥65 years of age (35.8% and 34.3%, respectively). To date, 297 deaths have been reported: 245 adults ≥65 years of age, 35 adults 45-64 years; 11 adults 20-44 years, one child 5-14 years of age, and 5 were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.
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FluWatch report: April 28 to May 4, 2013 (Week 18)
Posted 2013-05-10For readers interested in the <ABBR title="Portable Document Format">PDF</ABBR> version, the document is available for downloading or viewing:
<A title="Flu Watch (Version PDF, 113 KB - 6 pages)" href="http://www.phac-aspc.gc.ca/fluwatch/12-13/w18_13/pdf/fw2013-18-eng.pdf">FluWatch report: April 28 to May 4, 2013 (Week 18) (<ABBR title="Portable Document Format">PDF</ABBR> Version - 113 <ABBR title=Kilobytes>KB</ABBR> - 8 pages)
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Overall Summary
- Influenza activity in Canada continued its slow decline in week 18, with the percentage of laboratory tests positive for influenza at 10%. Influenza B was the predominant strain, but detections continued to decrease.
- Detections of rhinovirus continued to increase, while detections of other respiratory viruses were stable or decreasing in week 18.
- The ILI consultation rate increased slightly and was above the expected range. However, fewer regions reported localized activity compared to the previous week.
In week 18, seven regions [AB(1), ON(4), QC(1) and NB(1)] reported localized activity and 25 regions reported sporadic activity. The number of regions reporting widespread or localized activity decreased compared to the previous week (Figures 1 and 2). Six new influenza outbreaks were reported: five in long-term-care facilities and one in a school (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 18
Note: Influenza 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 (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions<SUP title="sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in">?</SUP> reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N<SUP>*</SUP>=58)
?sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012
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Influenza and Other Respiratory Virus Detections
The overall percentage of positive influenza tests decreased slightly compared to recent weeks, from 11.2 in week 17 to 10.0% in week 18. Detections of influenza B decreased for the second consecutive week, and represented 86.4% of total positive influenza detections in week 18 (Figure 4). Among the influenza viruses detected in week 18 (n=301), 13.6% were positive for influenza A viruses [of which 48.8% were A(H1N1)pdm09, 9.8% were A(H3), and 41.5% were A(unsubtyped)] (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 86.5% influenza A [34.5% A(H3), 4.6% A(H1N1)pdm09 and 61.0% A(unsubtyped)] and 13.5% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 23,888 cases to date this season (Table 2). The proportion of cases by age group is as follows: 14.1% <5 years; 9.9% between 5-19 years; 15.7% between 20-44 years; 17.0% between 45-64 years of age; 43.2% ≥65 years.
The percentage of positive tests for rhinovirus increased from 12.5% in week 17 to 14.1% in week 18, and has been slowly increasing since week 01. The percentage of positive tests for parainfluenza (5.4%) was stable since week 16, but has been increasing gradually over the past 10 weeks. The percentage of tests positive for respiratory syncytial virus (RSV) (4.5%) continued its decline from a peak in week 08. The percentage of positive tests for human metapneumovirus (hMPV) (5.0%) has been stable since week 16, and the percentage of positive tests for coronavirus (0.8%) has been decreasing slowly since week 04 (Figure 5)<SUP>*</SUP>.
* For more details, see the weekly Respiratory Virus Detections in Canada Report.
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION class=alignCenter>Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2012-2013
</CAPTION><THEAD><TR class=bg-colour-yellow><TH id=ar1 rowSpan=3>Reporting provinces</TH><TH id=ac1 colSpan=6>Weekly
(April 28 to May 4, 2013)
</TH><TH id=ac9 colSpan=6>Cumulative
(August 26, 2012 to May 4, 2013)
</TH></TR><TR class=bg-colour-yellow><TH id=ac2 colSpan=5 headers=ac1>Influenza A</TH><TH id=ac8 headers=ac1>Influenza
B
</TH><TH id=ac10 colSpan=5 headers=ac9>Influenza A</TH><TH id=ac16 headers=ac9>Influenza
B
</TH></TR><TR class=bg-colour-yellow><TH id=ac3 headers=ac2>A Total</TH><TH id=ac4 headers=ac2>A(H1)</TH><TH id=ac5 headers=ac2>A(H3)</TH><TH id=ac6 headers=ac2>Pand H1N1</TH><TH id=ac7 class=noWrap headers=ac2>A
( <ABBR title=unsubtyped>Un S</ABBR>)Table 1 note*
</TH><TH headers="ac1 ac8">Total</TH><TH id=ac11 headers=ac10>A Total</TH><TH id=ac12 headers=ac10>A(H1)</TH><TH id=ac13 headers=ac10>A(H3)</TH><TH id=ac14 headers=ac10>Pand H1N1</TH><TH id=ac15 class=noWrap headers=ac10>A
(Un S) Table 1 note*
</TH><TH headers=ac16>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=13>* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals. </TD></TR></TFOOT><TBODY><TR><TH id=ar2 class=bg-colour-yellow headers=ar1><ABBR title="British Columbia ">BC</ABBR></TH><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac3">3</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac5">1</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac6">2</TD><TD class=alignRight headers="ar1 ar2 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar2 ac1 ac8">11</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac11">1907</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac13">1450</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac14">218</TD><TD class=alignRight headers="ar1 ar2 ac9 ac10 ac15">239</TD><TD class=alignRight headers="ar1 ar2 ac9 ac16">397</TD></TR><TR><TH id=ar3 class=bg-colour-yellow headers=ar1><ABBR title=Alberta>AB</ABBR></TH><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac3">7</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac5">2</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac6">4</TD><TD class=alignRight headers="ar1 ar3 ac1 ac2 ac7">1</TD><TD class=alignRight headers="ar1 ar3 ac1 ac8">40</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac11">2347</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac13">1766</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac14">437</TD><TD class=alignRight headers="ar1 ar3 ac9 ac10 ac15">144</TD><TD class=alignRight headers="ar1 ar3 ac9 ac16">748</TD></TR><TR><TH id=ar4 class=bg-colour-yellow headers=ar1><ABBR title=Saskatchewan>SK</ABBR></TH><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac3">2</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar4 ac1 ac2 ac7">2</TD><TD class=alignRight headers="ar1 ar4 ac1 ac8">27</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac11">836</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac13">476</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac14">73</TD><TD class=alignRight headers="ar1 ar4 ac9 ac10 ac15">287</TD><TD class=alignRight headers="ar1 ar4 ac9 ac16">285</TD></TR><TR><TH id=ar5 class=bg-colour-yellow headers=ar1><ABBR title=Manitoba>MB</ABBR></TH><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac3">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar5 ac1 ac8">2</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac11">657</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac13">78</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac14">10</TD><TD class=alignRight headers="ar1 ar5 ac9 ac10 ac15">569</TD><TD class=alignRight headers="ar1 ar5 ac9 ac16">84</TD></TR><TR><TH id=ar6 class=bg-colour-yellow headers=ar1><ABBR title=Ontario>ON</ABBR></TH><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac3">7</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac5">1</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac6">4</TD><TD class=alignRight headers="ar1 ar6 ac1 ac2 ac7">2</TD><TD class=alignRight headers="ar1 ar6 ac1 ac8">57</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac11">8248</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac13">3778</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac14">369</TD><TD class=alignRight headers="ar1 ar6 ac9 ac10 ac15">4101</TD><TD class=alignRight headers="ar1 ar6 ac9 ac16">843</TD></TR><TR><TH id=ar7 class=bg-colour-yellow headers=ar1><ABBR title=Quebec>QC</ABBR>
</TH><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac3">12</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac6">2</TD><TD class=alignRight headers="ar1 ar7 ac1 ac2 ac7">10</TD><TD class=alignRight headers="ar1 ar7 ac1 ac8">109</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac11">9797</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac13">546</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac14">35</TD><TD class=alignRight headers="ar1 ar7 ac9 ac10 ac15">9216</TD><TD class=alignRight headers="ar1 ar7 ac9 ac16">1768</TD></TR><TR><TH id=ar8 class=bg-colour-yellow headers=ar1><ABBR title="New Brunswick">NB</ABBR>
</TH><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac3">6</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac6">6</TD><TD class=alignRight headers="ar1 ar8 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar8 ac1 ac8">13</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac11">1859</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac13">771</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac14">71</TD><TD class=alignRight headers="ar1 ar8 ac9 ac10 ac15">1017</TD><TD class=alignRight headers="ar1 ar8 ac9 ac16">60</TD></TR><TR><TH id=ar9 class=bg-colour-yellow headers=ar1><ABBR title="Nova Scotia ">NS</ABBR>
</TH><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac3">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar9 ac1 ac8">1</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac11">388</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac13">165</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac14">8</TD><TD class=alignRight headers="ar1 ar9 ac9 ac10 ac15">215</TD><TD class=alignRight headers="ar1 ar9 ac9 ac16">7</TD></TR><TR><TH id=ar10 class=bg-colour-yellow headers=ar1><ABBR title="Prince Edward Island ">PE</ABBR>
</TH><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac3">2</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac6">2</TD><TD class=alignRight headers="ar1 ar10 ac1 ac2 ac7">0</TD><TD class=alignRight headers="ar1 ar10 ac1 ac8">0</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac11">116</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac13">76</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac14">9</TD><TD class=alignRight headers="ar1 ar10 ac9 ac10 ac15">31</TD><TD class=alignRight headers="ar1 ar10 ac9 ac16">1</TD></TR><TR><TH id=ar11 class=bg-colour-yellow headers=ar1><ABBR title="Newfoundland/Labrador ">NL</ABBR>
</TH><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac3">2</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac5">0</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac6">0</TD><TD class=alignRight headers="ar1 ar11 ac1 ac2 ac7">2</TD><TD class=alignRight headers="ar1 ar11 ac1 ac8">0</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac11">717</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac13">152</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac14">0</TD><TD class=alignRight headers="ar1 ar11 ac9 ac10 ac15">565</TD><TD class=alignRight headers="ar1 ar11 ac9 ac16">16</TD></TR><TR><TH id=ar12 class=bg-colour-yellow headers=ar1>Canada</TH><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac3">41</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac4">0</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac5">4</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac6">20</TD><TD class=alignRight headers="ar1 ar12 ac1 ac2 ac7">17</TD><TD class=alignRight headers="ar1 ar12 ac1 ac8">260</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac11">26872</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac12">0</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac13">9258</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac14">1230</TD><TD class=alignRight headers="ar1 ar12 ac9 ac10 ac15">16384</TD><TD class=alignRight headers="ar1 ar12 ac9 ac16">4209</TD></TR></TBODY></TABLE>
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2012-2013 Table 2 note*
</CAPTION><THEAD><TR class=bg-colour-yellow><TH id=br1 rowSpan=3>Age groups</TH><TH id=bc1 colSpan=5>Weekly
(April 28 to May 4, 2013)
</TH><TH id=bc8 colSpan=5>Cumulative
(August 26, 2012 to May 4, 2013)
</TH></TR><TR class=bg-colour-yellow><TH id=bc2 colSpan=4 headers=bc1>Influenza A</TH><TH id=bc7 headers=bc1>B</TH><TH id=bc9 colSpan=4 headers=bc8>Influenza A</TH><TH id=bc14 headers=bc8>B</TH></TR><TR class=bg-colour-yellow><TH id=bc3 headers=bc2>A Total</TH><TH id=bc4 headers=bc2>Pandemic H1N1</TH><TH id=bc5 headers=bc2>A/H3N2</TH><TH id=bc6 headers=bc2>A unsubtyped</TH><TH headers="bc1 bc7">Total</TH><TH id=bc10 headers=bc9>A Total</TH><TH id=bc11 headers=bc9>Pandemic H1N1</TH><TH id=bc12 headers=bc9>A/H3N2</TH><TH id=bc13 headers=bc9>A unsubtyped</TH><TH headers=bc14>Total</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=11>* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively. </TD></TR></TFOOT><TBODY><TR><TH id=br2 headers=br1><5</TH><TD class=alignRight>5</TD><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>32</TD><TD class=alignRight>2674</TD><TD class=alignRight>214</TD><TD class=alignRight>861</TD><TD class=alignRight>1599</TD><TD class=alignRight>706</TD></TR><TR><TH id=br3 headers=br1>5-19</TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>34</TD><TD class=alignRight>1455</TD><TD class=alignRight>66</TD><TD class=alignRight>639</TD><TD class=alignRight>750</TD><TD class=alignRight>908</TD></TR><TR><TH id=br4 headers=br1>20-44</TH><TD class=alignRight>4</TD><TD class=alignRight>1</TD><TD class=alignRight>0</TD><TD class=alignRight>3</TD><TD class=alignRight>23</TD><TD class=alignRight>3170</TD><TD class=alignRight>339</TD><TD class=alignRight>1217</TD><TD class=alignRight>1614</TD><TD class=alignRight>586</TD></TR><TR><TH id=br5 headers=br1>45-64</TH><TD class=alignRight>4</TD><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>2</TD><TD class=alignRight>27</TD><TD class=alignRight>3463</TD><TD class=alignRight>312</TD><TD class=alignRight>1233</TD><TD class=alignRight>1918</TD><TD class=alignRight>597</TD></TR><TR><TH id=br6 headers=br1>65+</TH><TD class=alignRight>2</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>2</TD><TD class=alignRight>45</TD><TD class=alignRight>9611</TD><TD class=alignRight>132</TD><TD class=alignRight>3713</TD><TD class=alignRight>5766</TD><TD class=alignRight>718</TD></TR><TR><TH id=br7 headers=br1>Unknown</TH><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>0</TD><TD class=alignRight>166</TD><TD class=alignRight>20</TD><TD class=alignRight>144</TD><TD class=alignRight>2</TD><TD class=alignRight>1</TD></TR><TR><TH id=br8 headers=br1>Total</TH><TD class=alignRight>15</TD><TD class=alignRight>5</TD><TD class=alignRight>0</TD><TD class=alignRight>10</TD><TD class=alignRight>161</TD><TD class=alignRight>20539</TD><TD class=alignRight>1083</TD><TD class=alignRight>7807</TD><TD class=alignRight>11649</TD><TD class=alignRight>3516</TD></TR></TBODY></TABLE>
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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013
Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013
Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012
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Influenza strain characterizations
During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 1221 influenza viruses. The 600 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 193 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 338 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 90 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N =1221
Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012
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Antiviral resistance
During the 2012-13 season, NML has tested 1149 influenza viruses for resistance to oseltamivir, and 1145 influenza viruses for resistance to zanamivir. Among these, one A(H3N2) virus was resistant to oseltamivir and zanamivir. A total of 1180 influenza A viruses were tested for amantadine resistance and all but one were resistant (Table 3).
<TABLE class=widthFull border=1 cellSpacing=0 cellPadding=2><CAPTION>Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013</CAPTION><THEAD><TR class=bg-colour-yellow><TH id=cr1 rowSpan=2>Virus type and subtype</TH><TH id=cc1 colSpan=2>Oseltamivir</TH><TH id=cc4 colSpan=2>Zanamivir</TH><TH id=cc7 colSpan=2>Amantadine</TH></TR><TR class=bg-colour-yellow><TH id=cc2 headers=cc1># tested</TH><TH id=cc3 headers=cc1># resistant (%)</TH><TH id=cc5 headers=cc4># tested</TH><TH id=cc6 headers=cc4># resistant (%)</TH><TH id=cc8 headers=cc7># tested</TH><TH id=cc9 headers=cc7># resistant (%)</TH></TR></THEAD><TFOOT><TR><TD class=fontSize85 colSpan=7><SUP>*</SUP> NA - not applicable</TD></TR></TFOOT><TBODY><TR><TH id=cr2 class="alignLeft bg-colour-blue" headers=cr1>A (H3N2)</TH><TD class=alignRight headers="cr2 cc2">572</TD><TD class=alignRight headers="cr2 cc3">1 (0.2%)</TD><TD class=alignRight headers="cr2 cc5">573</TD><TD class=alignRight headers="cr2 cc6">1 (0.2%)</TD><TD class=alignRight headers="cr2 cc8">955</TD><TD class=alignRight headers="cr2 cc9">954 (99.9%)</TD></TR><TR><TH id=cr3 class="alignLeft bg-colour-blue" headers=cr1>A (H1N1)</TH><TD class=alignRight headers="cr3 cc2">194</TD><TD class=alignRight headers="cr3 cc3">0</TD><TD class=alignRight headers="cr3 cc5">190</TD><TD class=alignRight headers="cr3 cc6">0</TD><TD class=alignRight headers="cr3 cc8">225</TD><TD class=alignRight headers="cr3 cc9">225 (100%)</TD></TR><TR><TH id=cr4 class="alignLeft bg-colour-blue" headers=cr1>B</TH><TD class=alignRight headers="cr4 cc2">383</TD><TD class=alignRight headers="cr4 cc3">0</TD><TD class=alignRight headers="cr4 cc5">382</TD><TD class=alignRight headers="cr4 cc6">0</TD><TD class=alignRight headers="cr4 cc8">NA <SUP>*</SUP></TD><TD class=alignRight headers="cr4 cc9">NA <SUP>*</SUP></TD></TR><TR><TH id=cr5 class="alignLeft bg-colour-blue" headers=cr1>TOTAL</TH><TD class=alignRight headers="cr5 cc2">1149</TD><TD class=alignRight headers="cr5 cc3">1 (0.1%)</TD><TD class=alignRight headers="cr5 cc5">1145</TD><TD class=alignRight headers="cr5 cc6">1 (0.1%)</TD><TD class=alignRight headers="cr5 cc8">1180</TD><TD class=alignRight headers="cr5 cc9">1179 (99.9%)</TD></TR></TBODY></TABLE>
Influenza-like Illness (ILI) Consultation Rate
The national influenza-like-illness (ILI) consultation rate increased from 14.5 ILI consultations per 1,000 patient visits in week 17 to 17.6 / 1,000 in week 18, and is above the expected range (Figure 7). In week 18, the highest consultation rate was observed in children under 5 years of age (63.2/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)
Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
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Severe Respiratory Illness Surveillance
Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 18, 16 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 15 in week 17. All of the cases reported in week 18 were identified with influenza B. The age distribution is as follows: 3 (18.8%) between 0-5 months, 2 (12.5%) between 6-23 months, 4 (25.0%) 2-4 years of age, and 7 (43.8%) 5-9 years of age. Two cases were admitted to an intensive care unit (ICU) during week 18, one child 2-4 years of age and one 5-9 years of age; both with influenza B. No deaths were reported in week 18.
Since the start of the 2012-13 season, a total of 855 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 621 (72.6%) with influenza A [of which 120 (19.3%) were A(H3N2), 25 (4.0%) were A(H1N1)pdm09 and the remaining 476 were A(unsubtyped); and 234 (27.4%) with influenza B. The distribution of cases by age group is as follows: 157 (18.4%) <6 months of age; 199 (23.3%) age 6-23 months; 244 (28.5%) age 2-4 years; 183 (21.4%) age 5-9 years; and 72 (8.4%) age 10-16 years. Ninety-two (10.8%) of the 855 cases were admitted to the ICU. Of the 70 ICU admissions with available data, 60 (85.7%) cases had at least one co-morbidity. One death has been reported to date this season in a child 6-23 months of age with an underlying condition, with influenza B.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Adult Influenza Hospitalizations and Deaths (PCIRN)
PCIRN-SOS surveillance has concluded for the 2012-13 influenza season. In week 18, eight 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. All eight hospitalizations were cases of influenza B; three cases were ≥65 years of age, two were 45-64 years, two were 20-44 years and one was <20 years of age. Two ICU admissions were reported, both cases with influenza B; one ≥65 years of age and one 45-64 years of age. No deaths were reported in week 18. Only nine of the 17 PCIRN centres reported data in week 18. A summary of final data will be included in the 2012-13 FluWatch annual report.
From November 4, 2012 to May 4, 2013, 1,779 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,620 (91.1%) with influenza A [of which 310 were A(H3N2), 19 were A(H1N1)pdm09, and 1,291 were A(unsubtyped)]; 113 (6.4%) with influenza B, and the type has not been reported for 46 cases. The age distribution of hospitalizations is as follows: 1,212 (68.1%) were ≥65 years of age, 364 (20.5%) were 45-64 years, 194 (10.9%) were 20-44 years, and 9 (0.5%) were <20 years of age. ICU admission was required for 214 hospitalizations; the majority of which were adults ≥65 years of age (124; 57.9%). Of the ICU admissions, 90 (42.1%) had at least one co-morbidity, five (2.3%) had no co-morbidities, and 119 had no information to date. A total of 115 deaths have been reported: 26 with influenza A(H3N2), one with A(H1N1)pdm09, 82 with A(unsubtyped), five with influenza B, and one untyped. More than 85% of the deaths (98/115) were in adults ≥65 years of age, 14 (12.2%) were adults 45-64 years of age, and 3 (2.6%) were 20-44 years of age. Fifty-two (45.2%) deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining cases.
Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System<SUP>*</SUP>)
In week 18, 69 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories<SUP>*</SUP>. The majority of cases were influenza A (56.5%). The highest proportion of hospitalisations were in adults ≥65 years of age (40.6%), followed by children 0-4 years of age (21.7%). Of the 17 cases with available data, six cases were admitted to the ICU, three with influenza A(H1N1)pdm09 and three with influenza B; four were ≥65 years of age, one was 45-64 years of age, and one was 5-14 years of age. Two deaths were reported in week 18, both adults ≥65 years of age with influenza A.
To date this season, 4,733 influenza-associated hospitalizations have been reported, of which 89.1% have been influenza A. Of those subtyped (48.8%), influenza A(H3) was the predominant influenza strain. The cumulative proportion of hospitalizations with influenza B continues to increase (10.9% in week 18). Age information was available for 4,730 cases, and the age distribution is as follows: 2,518 (53.2%) were ≥65 years of age; 789 (16.7%) were 45-64 years of age; 429 (9.1%) were 20-44 years of age; 40 (0.8%) were 15-19 years of age; 228 (4.8%) were 5-14 years; and 726 (15.3%) were 0-4 years of age. Of the 1,293 cases with available data, there have been 204 hospitalisations for which admission to an ICU was required; the highest proportions have been in adults 45-64 years of age, followed by adults ≥65 years of age (35.8% and 34.3%, respectively). To date, 297 deaths have been reported: 245 adults ≥65 years of age, 35 adults 45-64 years; 11 adults 20-44 years, one child 5-14 years of age, and 5 were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.
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