Kira Sviderskaia, University of Alberta

Kira Sviderskaia1, Tak Fan Eric Chau2, Jo Lin Chew2, Pranavi Thota1, Tamara Semeria Maitret3, Bruce Ritchie1, Karina Top2, Vanessa Meier-Stephenson1,3,5 1 Department of Medicine, University of Alberta 2 Department of Pediatrics, University of Alberta 3 Department of Laboratory Medicine & Pathology 4 Li Ka Shing Institute of Virology, University of Alberta 5 Department of Medical Microbiology and Immunology, University of Alberta

Fighting & Responding

Measles remains a major public health concern, as Canada has lost its measles elimination status in 2025 due to the on-going outbreak currently counting over 5500 cases. Our study aims to assess the Edmonton metropolitan region population immunity levels by testing the presence of measles-specific IgG antibodies and T cell activation levels in cohorts stratified by age. Serum and PBMCs, collected 2020-2024, were acquired from the Canadian BioSample Repository. 160 participants were grouped by birth year into 10-year cohorts from 1920s to 2000 and after, balanced for number and sex. ELISA responses were assigned as negative <150 mIU/ml; equivocal 150-200, and positive>200 mIU/ml. Using a two-side Cochran–Armitage test (Z=-4.04, p=5.4e-05), we showed a significant decrease in antibody prevalence with increasing birth year – participants born before 1970 showed 91-100% seroprevalence, compared to 60-85% in younger cohorts. Notably, AHS presumes those born before 1970 to have natural immunity, meanwhile 1970s correspond to the 1st generation of children to have received the MMR vaccine. Measles specific T-cell immunity will be assessed with FluoroSpot to evaluate the level of protection in IgG-negative/ equivocal individuals. These results could help direct the development of public policy and the necessary interventions, like public awareness and education, or targeted immunization campaigns.