More than 17 million Canadians were infected with the COVID-19 Omicron variant in five months, according to a review of 21 antibody testing studies by a government task force.
Canada's COVID-19 Immunity Task Force (CITF) analyzed the studies to provide a clearer picture of the scale of the Omicron wave in the country.
Before the arrival of the Omicron variant, approximately 7% of Canadians had infection-acquired antibodies to SARS-CoV-2. Between December 2021 and May 2022, the proportion rose by 45%, according to the findings.
The percentage represents an average of more than 100,000 infections per day during the period, CTIF Executive Director Dr. Tim Evans said in a statement. "New sublineages in the Omicron line have been continuing to spread since then, and the percentage of Canadians who have had a SARS-CoV-2 infection is now likely well above 50%," he added.
The studies relied on the analysis of blood donations made to Canadian Blood Services, which provides the CITF with updated information every two weeks. CITF has supported more than 100 studies across Canada that are generating insights on the levels, trends, nature, and duration of immunity arising from SARS-CoV-2 infection and COVID-19 vaccination.