+ Weekly / Influenza News Week 43 (October 23 to October 29, 2016) Summary of Influenza Activity in Toronto for Week 43 Indicator (Click on the indicator Activity Level * Description name for more details) Reported Cases Comparable One new lab-confirmed cases of influenza was reported in week 43, compared to two cases reported in week 42. To date this season, the number of lab-confirmed Influenza Strains Four new isolates characterized cases is higher than the previous 10-season mean. As of week 43, four isolates have been characterized, two as A/California/07/2009-like H1N1 and two as B/Phuket/3073/2013-like virus. Institutional Outbreaks No report There have been no institutional outbreaks reported for the 2016/17 season as of week 43. Absenteeism in Schools Comparable The overall absenteeism rate for week 43 was comparable to the expected rate. Overall Influenza activity in Toronto for week 43 was comparable to the activity in week 42. * May not reflect significant changes, but describes overall observed trends. Starting in the 2015/16 season, the Ontario Ministry of Health and Long-Term Care has changed the requirements for case follow-up and data entry into iphis. As a result, data from the 2016/17 season are not directly comparable to those in seasons prior to 2015/16. In particular, subtype information will be available for a smaller proportion of cases, and hospitalization and death information will be underestimated and not be comparable to previous years. Please refer to the technical notes for details. Data as of: 04/11/16 1 of 11
Recent Influenza Reporting: - continued Overall influenza activity in Toronto for week 43 was comparable to that of week 42, with one new lab-confirmed cases of influenza reported during this week compared to two cases in the previous week. The case in week 43 was subtyped as influenza A (Table 1). To date this season, 19 lab-confirmed cases of influenza have been reported, higher than the previous 10-season mean of 10 cases (Table 3). As of week 43, no outbreaks have been reported for Toronto institutions for the 2016/17 season (Table 1). Table 1. Summary of new and cumulative influenza cases and institutional outbreaks by virus type and subtype*. Reported in week 43 (October 23 to October 29, 2016) and 2016/17 season-to-date (September 1, 2016 to October 29, 2016). Lab-confirmed Influenza cases Week 43 (%) Season-to-Date (%) Influenza A (H1N1) pdm09 0 (0) 1 (5) Influenza A (Not Subtyped/No Subtype) 1 (100) 8 (42) Influenza A (Seasonal H3) 0 (0) 5 (26) Influenza B 0 (0) 5 (26) Influenza A and B 0 (0) 0 (0) Total cases 1 (100) 19 (100) Institutional outbreaks 0 0 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis), extracted [03/11/2016]. *Subtype information will be available for a smaller proportion of influenza A cases than in previous years due to changes in processing and investigation of cases that started in the 2015/16 season. Please refer to technical notes for details. The week that the diagnosing health unit was first notified of the case's episode. Lab-confirmed cases include all reports of sporadic influenza cases and a subset of new outbreak associated cases. This reflects the number of respiratory outbreaks confirmed to be caused by influenza during the week of interest. Data as of: 04/11/16 2 of 11
- continued Influenza Strains: As of November 4, 2016, four new influenza isolates for Toronto cases have been received from the National Microbiology Laboratory (NML) for the current season (Table 2). Two were antigenetically characterized as A/California/07/2009-like H1N1, included in the 2016/17 season trivalent influenza vaccine, and two as B/Phuket/3073/2013-like virus, included in the 2016/17 quadrivalent influenza vaccine (Table 2). Table 2. Summary of influenza strains characterized by National Microbiology Lab (NML)* for Toronto cases. September 1, 2016 to October 29, 2016. Strains Number of isolates Influenza A A/California/07/2009-like H1N1 2 Total Influenza A 2 Influenza B B/Phuket/3073/2013-like virus 2 Total Influenza B 2 Total characterized strains 4 Source: National Microbiology Laboratory, as of [04/11/2016]. *The NML receives and characterizes only a subset of influenza positive specimens from the Public Health Ontario Laboratory (PHOL). Characterization data reflect results of haemmagglutination inhibition (HAI) testing compared to the reference influenza strains recommended by WHO. There is a lag in characterization Components included in the 2016/2017 trivalent influenza vaccine are: an A/California/7/2009(H1N1)pdm09-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus, and a B/Brisbane/60/2008-like virus. The 2016/2017 quadrivalent influenza vaccine includes the above three viruses and a B/Phuket/3073/2013-like virus. Data as of: 04/11/16 3 of 11
- continued Figure 1. Number and rate* of reported lab-confirmed influenza cases by influenza type and reported week. Toronto, comparison of reported cases, 2016/17 season-to-date and 10-year mean (2006/07 to 2015/16). 20 Influenza A 0.16 Influenza B 2016/17 incidence rate 0.14 Number of reported cases 15 10 5 Historical mean and 95% confidence intervals 0.12 0.10 0.08 0.06 0.04 Reported cases per 100,000 population 0.02 0 36 37 38 39 40 41 42 43 0.00 Reported week Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis), extracted [03/11/2016] *Cases per 100,000 population. Population source: Intellihealth [August 26, 2016]. The week that the diagnosing health unit was first notified of the case's episode. The 10-year-mean excludes all pandemic influenza cases reported after week 14 of the 2008/09 season until the end of the 2009/10 season. Data as of: 04/11/16 4 of 11
- continued Table 3. New lab-confirmed influenza cases reported in week 43 compared to the cumulative number of lab-confirmed influenza cases for the 2016/17 season-to-date and the 10-year mean (2006/07-2015/16) by age group. Age group (years) Number of cases (%) Number of cases (%) season-to-date* Week 43 2016/17 10-year mean (2006/07-2015/16) < 1 0 (0) 1 (5) 0 (3) 1 to 4 0 (0) 0 (0) 1 (9) 5 to 14 0 (0) 0 (0) 0 (3) 15 to 24 0 (0) 1 (5) 0 (4) 25 to 44 0 (0) 2 (11) 1 (8) 45 to 64 0 (0) 7 (37) 2 (20) 65+ 1 (100) 8 (42) 5 (52) Unknown 0 (0) 0 (0) 0 (100) Total 1 (100) 19 (100) 10 (100) Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis), extracted [03/11/2016]. *All cases reported since September 1st of each season. Due to a potential lag in entry of influenza cases in the 2015/16 season, the number of cases with reported dates in the current week may be an underestimate and will increase as more cases are entered in coming weeks. Please refer to technical notes for details. All influenza A (H1N1) pdm09 cases reported after week 14 for the 2008/09 season and for the entire 2009/10 season were excluded from the 10-year mean. The total for season to date may fluctuate as missing ages prevent classification of cases in their week of report. Percentages and the 10-year mean are rounded up. Data as of: 04/11/16 5 of 11
- continued 9 Figure 2. Number and rate* of reported lab-confirmed influenza cases by age group Toronto, September 1, 2016 to October 29, 2016. 3.5 8 Number of Cases Age-specific Rate 3.0 Number of reported cases 7 6 5 4 3 2 1 2.5 2.0 1.5 1.0 0.5 Number of cases per 100,000 population 0 <1 1-4 5-14 15-24 25-44 45-64 65+ Age group (years) 0.0 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis), extracted [03/11/2016]. *Cases per 100,000 population. Population source: Intellihealth August 26, 2016. Data as of: 04/11/16 6 of 11
- continued Table 4. Summary of influenza hospitalizations and deaths, by virus type and subtype*. Season-to-date (September 1, 2016 to October 29, 2016). Hospitalizations Deaths Season-to-date (%) Season-to-date (%) Lab-confirmed influenza cases Influenza A (H1N1) pdm09 0 (0) 0 Influenza A (Not Subtyped/No Subtype) 2 (40) 0 Influenza A (Seasonal H3) 1 (20) 0 Influenza B 2 (40) 0 Total lab-confirmed influenza cases 5 (100) 0 Non lab-confirmed influenza cases 0 0 Total cases 5 0 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis), extracted [03/11/2016]. *Subtype information may not be conducted for all cases as the laboratory testing algorithm changes throughout the season. Due to changes in the methodology of processing and investigation of influenza cases starting in the 2015/16 season, hospitalizations and deaths will be underestimated and not comparable to previous years. Newly reported deaths (among sporadic, outbreak associated or ILI cases) may include deaths occurring during this report week and/or deaths which had been reported as new cases/ili in previous weeks, but who were not deceased when they were originally reported as a case. The contribution of influenza to the death in the lab-confirmed influenza case could not be determined. Lab-confirmed cases include all reports of sporadic influenza cases and a subset of new outbreak associated cases. Non lab-confirmed cases are cases with ILI who are epi-linked to lab-confirmed cases and part of an institutional outbreak. Percentages for each subtype may not sum to total due to rounding. Data as of: 04/11/16 7 of 11
Institutional Outbreaks: - continued For the purposes of this report, institutions include: long-term care homes, acute care hospitals, complex care hospitals, special care facilities, retirement homes and rehabilitation hospitals in Toronto. As of week 43, there have no reports of influenza outbreaks in Toronto institutions for the 2016/17 season. Data as of: 04/11/16 8 of 11
Absenteeism in Schools: - continued Overall, the absenteeism rate for elementary school children attending both school boards was comparable to the rate expected for week 43 (Figure 4). Six percent of all elementary schools had more than 10% absenteeism and the overall absenteeism rate was 6% in week 43. Figure 3. Overall all-cause absenteeism rate for all elementary schools by day. TDSB and TCDSB combined. 2016/17 school year compared to previous 3- year* mean (2013/14 to 2015/16), year-to-date. Proportion of students absent (%) 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 0% 2016/17 3-year mean 36 37 38 39 40 41 42 43 Week Toronto Public Health (TPH) receives all-cause student absenteeism data weekly from the Toronto District School Board (TDSB) and the Toronto Catholic District School Board (TCDSB) for all elementary schools. Data are received for the previous school week. The school week runs from Monday to Friday, versus the influenza reporting week which runs from Sunday to Saturday. September 5 2016 and October 12 2016 were holidays, and October 7 2016 was a PA day. *Absenteeism data for the TDSB and TCDSB only became available as of week 46 for the 2013/2014 seasonn. Two-year means were calculated for weeks 36 to 45. Data as of: 04/11/16 9 of 11
For related influenza information visit: ONTARIO Most recent Ontario Respiratory Virus Bulletin: http://www.publichealthontario.ca/en/servicesandtools/surveillanceservices/pages/ontario- Respiratory-Virus-Bulletin.aspx#.UoOpdHDks2s CANADA Most recent Public Health Agency of Canada FluWatch: http://www.phac-aspc.gc.ca/fluwatch/ INTERNATIONAL The most recent WHO influenza updates: http://www.who.int/csr/disease/influenza/en/index.html The current WHO phase of pandemic alert for avian influenza H5N1: http://www.who.int/influenza/preparedness/pandemic/h5n1phase/en/index.html Data as of: 04/11/16 10 of 11
Influenza surveillance weeks, 2016/17 season Week Start End 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 04-Sep-16 11-Sep-16 18-Sep-16 25-Sep-16 02-Oct-16 09-Oct-16 16-Oct-16 23-Oct-16 30-Oct-16 06-Nov-16 13-Nov-16 20-Nov-16 27-Nov-16 04-Dec-16 11-Dec-16 18-Dec-16 25-Dec-16 01-Jan-17 08-Jan-17 15-Jan-17 22-Jan-17 29-Jan-17 05-Feb-17 12-Feb-17 19-Feb-17 26-Feb-17 05-Mar-17 12-Mar-17 19-Mar-17 26-Mar-17 02-Apr-17 09-Apr-17 16-Apr-17 23-Apr-17 30-Apr-17 07-May-17 14-May-17 21-May-17 28-May-17 04-Jun-17 11-Jun-17 18-Jun-17 25-Jun-17 02-Jul-17 09-Jul-17 16-Jul-17 23-Jul-17 30-Jul-17 06-Aug-17 13-Aug-17 20-Aug-17 27-Aug-17 10-Sep-16 17-Sep-16 24-Sep-16 01-Oct-16 08-Oct-16 15-Oct-16 22-Oct-16 29-Oct-16 05-Nov-16 12-Nov-16 19-Nov-16 26-Nov-16 03-Dec-16 10-Dec-16 17-Dec-16 24-Dec-16 31-Dec-16 07-Jan-17 14-Jan-17 21-Jan-17 28-Jan-17 04-Feb-17 11-Feb-17 18-Feb-17 25-Feb-17 04-Mar-17 11-Mar-17 18-Mar-17 25-Mar-17 01-Apr-17 08-Apr-17 15-Apr-17 22-Apr-17 29-Apr-17 06-May-17 13-May-17 20-May-17 27-May-17 03-Jun-17 10-Jun-17 17-Jun-17 24-Jun-17 01-Jul-17 08-Jul-17 15-Jul-17 22-Jul-17 29-Jul-17 05-Aug-17 12-Aug-17 19-Aug-17 26-Aug-17 02-Sep-17 Data as of: 04/11/16 11 of 11