Influenza & Other Modelling Activities at the Public Health Agency of Canada (PHAC)

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Influenza & Other Modelling Activities at the Public Health Agency of Canada (PHAC) Teresa Mersereau and Dena Schanzer, Public Health Agency of Canada Pan-InfORM and

1 Influenza & Other Modelling Activities at the Public Health Agency of Canada (PHAC) Teresa Mersereau and Dena Schanzer, Public Health Agency of Canada Pan-InfORM and NCCID Co-hosted Workshop: Use of Mathematical Modelling in Public Health Decision Making for Infectious Diseases Fort Gary Hotel Winnipeg, Manitoba Ocotober 6-7, 2014

2 Outline 1. Background 2. Influenza Surveillance in Canada 3. Influenza Modeling Activities at PHAC 4. Other Modeling Activities at PHAC 5. Challenges 6. Conclusions 2

3 Background Mathematical modelling has wide applications, including in public health and health policy Mathematical models can project plausible scenarios, guide control strategies and identify important areas for urgent research (Pan-InfORM, 2009) Modelling helps helps quantify and predict key public health outcomes including total number of persons infected, medically attended, hospitalized, and fatalities, as well as total antiviral and vaccine use. 3

4 Background Mathematical Modeling for Influenza Why is it important to study and monitor Influenza? Every year 10-20% of Canadians are infected with influenza In Canada it is estimated that there are 3,500 deaths and over 12, 200 hospitalizations each year Pandemics in 1889, 1918, 1957, 1968, 2009 Spanish Flu of 1918 The most deadly disease event in human history (World Health Organization). Infected 500 million people worldwide with death toll range of million. Recent emergence of several swine variant influenza strains in humans to US and Canada Recent and 1 st importations of human avian influenza (H5N1) in Canada 4

5 Influenza Surveillance in Canada Seasonal Influenza in Canada is nationally reportable and in most PT jurisdictions (with some exceptions) FluWatch is Canada's national surveillance system that monitors the spread of flu and flu-like illnesses including strain characterizations, antiviral profile, geographic spread, ages affected, spectrum of illness, and outcomes -all in near real time FluWatch reports contain specific information on flu and other respiratory viruses circulating in Canada. FluWatch program receives weekly data from a network of labs, hospitals, health care provided offices/clinics and provincial and territorial ministries of health 5

6 Modelling Influenza Allows for preparedness for various seasonal influenza scenarios» Mild to severe seasonal projections» Implications for vaccine ordering and preparedness, prioritizing immunization for risk groups, immunization campaign programming» Predicts health care utilization 6

7 Defining PHAC s modelling Requirements PHAC uses modelling combined with economic analysis to support decision-making with best available information» Supports forecasting/projections, decision-making» Synthesis of multiple data sources» Evaluation of new and alternative interventions and programmes» Determining burden of illness» Examining the value for money for policies, programs and interventions 7

8 Defining PHAC s modelling Requirements What are the questions that need to be answered?» Questions are diverse and ranging e.g. What is the cost-effectiveness of a specific antiviral?, What predicted amount of hospital burden will be attributable to seasonal influenza?, Who is at highest risk for adverse outcomes? Prioritizing the questions» Issues that are most relevant for the Canadian population» Questions that identify populations at-risk for vaccine preventable diseases and recommends specific vaccine use 8

9 Influenza Modelling Activities at PHAC Modelling provides supplemental information to routine influenza surveillance indicators Modelling results and projections can be used for public health decision and policy setting Burden of disease attributable to influenza Schanzer DL et al (2013) This study aimed to provide annual estimates of the mortality and hospitalization burden attributable to both seasonal influenza and the 2009 A/H1N1 pandemic influenza for Canada, and to discuss issues related to the reliability of these estimates. Impact of influenza on workforce absenteeism and productivity Schanzer DL et al (2011) The objective of this study was to estimate absenteeism rates and hours lost due to seasonal influenza and compare these estimates with estimates of absenteeism attributable to the two H1N1 pandemic waves that occurred in

10 Influenza Modeling Activities at PHAC Threshold/signal detection analysis to predict seasonal influenza onset Planning for the national antiviral stockpile:» Planning for stockpile of antivirals» Cost of maintaining the stockpile In the pandemic setting, PHAC led activities related to projections related to the burden of disease to inform planning and decision-making. 10

11 Other Modelling Activities at PHAC In addition to having some modelling expertise in-house PHAC also works with other experts to assist in the development of recommendations and other initiatives. Some recent examples where PHAC collaborated with and sponsored the work of researchers include in modelling HPV burden of disease and cost effectiveness for the implementation of HPV vaccine programs for boys, cost-effectiveness for the implementation of rotavirus vaccine program as well as for the cost effectiveness of the zoster vaccine. PHAC also sponsored work examining the incremental cost-effectiveness of using a QIV versus a TIV vaccine 11

12 Challenges Incomplete data Non-standardized and bias in data Properly defining and selecting parameters Defining working assumptions Challenges with respect answering the specific question asked 12

13 Challenges Modelling projections in a timely manner to inform public health policy and decision making Modelling using correct and complete data» Safeguards should be in place to ensure the data is as accurate as possible» Data does not cover 100% of the population Not all cases of influenza are reported Fitting the right model to answer the research question» To ensure the research question is being answered, one should chose the right kind of model and include all pertinent adjustment factors 13

14 Challenges Interpretation of models» An understanding of the model is required in order to draw conclusions from the statistical output Underlying assumptions» The modeller knows which variables are relevant Limitations of the models» Models are only as good as their data» Missing information may alter the results» Modelling represents a prediction, not a certainty 14

15 Conclusion PHAC uses modelling to support public health policy setting and decision making Questions should be identified and prioritized prior to the model being created Modelling allows PHAC to understand and prepare for influenza and inform policy action Modelling has many advantages, but only if process is done correctly Future opportunities include increasing collaboration with partners to improve the models used to protect Canadians 15

16 16 QUESTIONS?

17 References Schanzer DL, Sevenhuysen C, Winchester B, Mersereau T. Estimating influenza deaths in Canada, PLoS One Nov 27;8(11):e doi: /journal.pone ecollection 2013 Dena L Schanzer, Hui Zheng, and Jason Gilmore Statistical estimates of absenteeism attributable to seasonal and pandemic influenza from the Canadian Labour Force Survey BMC Infect Dis. 2011; 11: 90 17

Manitoba Influenza Surveillance Report

Manitoba Influenza Surveillance Report 212/213 Season Summary: Week 47: Nov 18-24, 212 The influenza-like-illness rate was 4.8% with 5% of sentinel physician sites reporting. There was one case of influenza