Measles is re-emerging in countries and regions where it was previously controlled, demanding a change in our thinking about the disease. The vulnerability of Canada and the potential gap in immunity to measles of its residents was recently exposed with large outbreaks in several provinces, coinciding with a resurgence of cases across Europe and Africa. These unexpected outbreaks were a warning that Canada cannot currently predict its risk of measles epidemics. The aims of this study are to determine whether Canada meets the level of population immunity required for measles elimination, and to identify which groups in Canada may be at higher risk of measles outbreaks.

Blood samples will be obtained from the Canadian Health Measures Survey (CHMS), a nationally representative survey developed by Statistics Canada, and also from patients presenting for a range of diagnostic testing in Ontario. Samples will be tested for measles antibodies, and epidemiological analyses will be performed to determine national and provincial population immunity estimates by age/sex-band, and whether born in Canada. CHMS and Ontario sera will be compared to determine which sample type is more appropriate. In addition to determining the current levels of immunity to measles in Canada, data from this study will be used to parameterize a mathematical model as part of a linked CIRN proposal led by Dr. Marc Brisson. This model will be used to assess the effect of waning immunity and variation in immunity between age-groups on our risk of measles epidemics in the future.

Team Members:

• Shelly Bolotin, Project Lead, Public Health Ontario
• Natasha Crowcroft, Public Health Ontario
• Todd Hatchette, Dalhousie University
• Alberto Severini, University of Manitoba
• Cecile Tremblay, University of Montréal
• Bouchra Serhir, Institut national de santé publique du Québec
• Tony Mazzulli, Mt. Sinai Hospital
• Shelley Deeks, Public Health Ontario
• Sarah Wilson, Public Health Ontario
• Scott Halperin, Dalhousie University
• Marc Brisson, Laval University
• Heather Deehan, Public Health Agency of Canada
• Ian Gemmill, KFL&A Public Health