Canada's COVID-19 infections among adults tripled in early 2022: study

TORONTO — The number of Canadian adults infected with COVID-19 tripled during the fifth wave of the pandemic compared with the total number of adults infected in the previous four waves, according to a new study led by Toronto researchers.

More than 5,000 Canadian adults — members of the Angus Reid Forum, a public polling cohort — took part in the fourth phase of the Action to Beat Coronavirus study. The findings were published as a letter to the editor in The New England Journal of Medicine Wednesday.

The adult participants took a self-administered dried blood spot test between Jan. 15 and March 15, 2022 and sent the samples back to the researchers for analysis. The team then tested the samples for antibodies related to COVID-19.

From those results, the team found nearly 30 per cent of Canadian adults were infected amid the first Omicron wave compared with roughly 10 per cent who were infected in the previous four waves. Of those fifth wave infections, one million were among the country's 2.3 million unvaccinated adults, the study says.