Local Influenza Surveillance Bulletin Released October 31, 2016

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1 Local Influenza Surveillance Bulletin Released October 31, 2016 Released November 28, 2016 Current Assessment of Influenza Activity in Waterloo Region As of November 28, 2016, there have been 6 laboratory confirmed cases of influenza (4 influenza A and 2 influenza B) and 0 institutional influenza outbreaks reported in Waterloo Region this season. Among laboratory-confirmed cases of influenza in Waterloo Region, there have been 2 hospitalizations 1 and 0 deaths. 2 To date, 1 case has been travel-related and 5 cases were locally acquired. Influenza Activity: August 28, 2016 to November 19, 2016 (Weeks 35 to 46) Figure 1: Number of reported 3 laboratory confirmed cases of influenza by week and type, Waterloo Region, August 28, 2016 to November 19, Source: iphis, Ministry of Health and Long-Term Care (MOHLTC), extracted November 28, In the season, only a proportion of laboratory confirmed cases are being followed up by public health units; therefore, the number of hospitalized cases may not be representative of the true burden of illness in the Waterloo Region population due to possible underreporting. 2 Includes deaths where influenza was the underlying cause, and where influenza was a contributing factor, but not the underlying cause. In the season, only a proportion of laboratory confirmed cases are being followed up by public health units; therefore, the number of deaths may not be representative of the true burden of illness in the Waterloo Region population due to possible underreporting. 3 Reported laboratory confirmed cases are based on case reported date which needs to be interpreted with caution due to the lag between the onset of illness, hospital admission, or death and reporting of the infection to public health. 4 The week numbers referenced throughout the bulletin refer to FluWatch weeks, which are established by the Public Health Agency of Canada. 1

2 Figure 2: Rates 5 of reported laboratory confirmed cases of influenza by week, Waterloo Region and Ontario and Waterloo Region previous five season historical average Waterloo Region current rate Waterloo Region 5 year average rate Ontario current rate 4 Rate per 100, Case Reported Week Source: iphis, MOHLTC, extracted November 28, Ontario Respiratory Pathogen Bulletin: Week 43. Population estimates ( ), 2011 Census (Table ), Statistics Canada, extracted April 26, Table 1: Number of reported laboratory confirmed influenza cases and incidence rates, by age group, Waterloo Region, August 28, 2016 to November 19, 2016 Age Group Number of cases Age-specific Rate per 100,000 0 to to Source: iphis, MOHLTC, extracted November 28, Population estimates ( ), 2011 Census (Table ), Statistics Canada, extracted April 26, Crude rates are presented throughout the bulletin, and thus are not age-standardized. Caution should be used when comparing crude rates across different geographical areas (i.e., Waterloo Region and Ontario), because part of the difference may be attributable to the differences in age distribution between the two populations. 2

3 Table 2: Influenza indicators 6,7,8, Waterloo Region and Ontario, August 28, 2016 to November 19, 2016 Waterloo Region Ontario Indicator Number Rate per 100,000 Number Rate per 100,000 Laboratory confirmed cases Hospitalized confirmed cases Deaths among confirmed cases Institutional outbreaks 8 0 NA 9 NA Source: iphis, MOHLTC, extracted November 28, Ontario Respiratory Pathogen Bulletin: Week 46. Population estimates ( ), 2011 Census (Table ), Statistics Canada, extracted April 26, School Absenteeism Surveillance Monitoring school absenteeism rates is an indicator of the level of community transmission of influenza. An absenteeism rate of 10 per cent or greater has been identified as a threshold by the Ministry of Health and Long Term Care (MOHLTC) to signify higher than expected levels of school absenteeism. The figure below shows the per cent absent of all schools, the average per cent absent of the previous five years of all schools in Waterloo Region by week, the overall average absenteeism of the previous five years, and the overall average of the previous five years plus two standard deviations. 6 In the season, only a proportion (20 per cent) of laboratory confirmed cases are being followed up by public health units; therefore, the number of hospitalized cases may not be representative of the true burden of illness in the Waterloo Region and Ontario population due to possible underreporting. 7 Includes deaths where influenza was the underlying cause, and where influenza was a contributing factor, but not the underlying cause. In the season, only a proportion (20 per cent) of laboratory confirmed cases are being followed up by public health units; therefore, the number of deaths may not be representative of the true burden of illness in the Waterloo Region and Ontario population due to possible underreporting. 8 The number of outbreaks reported is based on the onset date of illness for the first case in an outbreak meeting the provincial outbreak definition. 3

4 Figure 3: School Absenteeism, Waterloo Region, August 28, 2016 to November 18, Cumulative 5 season average Previous 5 season weekly average Cumulative 5 season average plus 2 standard deviations 6% 5% Per cent absent 4% 3% 2% 1% 0% 36* 37 38* *42* * * 1* 2 3 4* 5* 6 7 8* * *15*16* 17 18* *22* Week of the year *Indicates incomplete/partial data due to school closure (e.g. PA day, secondary school exams, statutory holiday, school break, or snow day). Source: Waterloo Region District and Catholic School Boards, extracted November 28, Influenza Strain Characterization Interpretation: Based on the small sample of influenza strains typed to date, it is difficult to determine how well the circulating strains are a match to the recommended vaccine components this season. However, so far the characterized strains are demonstrating to be either similar to or related to the recommended vaccines. Vaccines used in Ontario: In Ontario, both the trivalent and quadrivalent influenza vaccines are available this season as recommended by the World Health Organization (WHO) for the season. The trivalent influenza vaccine is recommended for use in adults and includes: A/California/7/2009(H1N1) pdm09-like virus, A/Hong Kong/4801/2014 (H3N2)-like virus, and B/Brisbane/60/2008-like virus. The quadrivalent vaccine is recommended and publicly funded for use among children 2 to 18 years of age as it includes the addition of a second influenza B component: B/Phuket/3073/2013-like virus. Details: In order to determine how well the influenza vaccine for the season matches with the strains exhibited in the population, Figure 4 shows the breakdown of influenza strains characterized by the National Microbiology Laboratory (NML) to date. As of November 19, 2016, the NML has characterized 91 influenza viruses from Canadian laboratories. 4

5 Figure 4: Strain characterization completed on influenza isolates, August 28, 2016 to November 19, 2016, Canada, N = 91 9,10 Influenza A (H3N2) Antigenically A/Hong Kong/4801/2014-like 9 35% Genetically A/Hong Kong/4801/2014-like 10 49% Influenza A (H1N1) A/California/7/2009-like 5% Influenza B B/Brisbane/60/2008-like (Victoria lineage) 8% B/Phuket/3073/2013-like (Yamagata lineage) 2% Source: National Microbiology Laboratory, extracted November 28, Provincial and National Influenza Surveillance For more information on influenza for the season, please visit the following websites: Public Health Ontario, Ontario Respiratory Pathogen Bulletins: Respiratory-Virus-Bulletin.aspx Public Health Agency of Canada, FluWatch Reports: 9 Viruses antigenically similar to A/Hong Kong/4801/2014, the A(H3N2) component of the trivalent and quadrivalent vaccine. 10 Viruses belonging to a genetic group for which most viruses were antigenically related to A/Hong Kong/4801/2014, the A(H3N2) component of the trivalent and quadrivalent vaccine. 5

6 Contact Information Region of Waterloo Public Health and Emergency Services Epidemiology and Health Analytics Team 99 Regina Street South, Third Floor Waterloo, Ontario, N2J 4V3 Canada Phone: Fax: TTY: Website: Accessible formats of this document are available upon request. Please call the Coordinator, Marketing and Communications at ext. 2244, (TTY ) to request an accessible format. Internal access to report: DOCS # The Epidemiology and Health Analytics Team would like to express thanks to all of the local influenza partners for their contributions to this year s influenza surveillance program. 6