Very Few Canadians Infected with SARS-CoV-2

Canadian Blood Services and Canada’s COVID-19 Immunity Task Force (CITF) announced results from their collaborative nine-province SARS-CoV-2 seroprevalence study that suggests that 1.5 % of healthy Canadians had been exposed to SARS-CoV-2, the virus causing COVID-19.

“Although this represents a doubling in comparison to an initial report following the first wave in May and June 2020, the overall seroprevalence – the number of people with antibodies, which suggests a previous COVID-19 infection – remains very low."

"Canada remains a long way from herd immunity,” said CITF Executive Director Tim Evans, in a press release.

This analysis is based on 33,860 blood samples from blood donor centers across Canada (excluding Quebec and the Territories) collected in October and November 2020. Donors aged between 17 and 24 years old had the highest seroprevalence rates (2.97%).

Dr. Catherine Hankins, CITF Co-Chair, added: “However, even using serology to add cases to our count that never came to light through formal diagnostic tests, it is clear that the vast majority of Canadians remain vulnerable to COVID-19. We have no choice but to keep up public health measures until vaccine-induced immunity grows substantially.”

Canadian Blood Services is moving towards using a new assay to test blood samples that will allow them to differentiate between infection-acquired and vaccine-acquired immunity.