More than 17 million Canadians have been infected with the Omicron variant of the coronavirus. This represents more than 100,000 contaminations per day since the arrival of this strain in the country, according to estimates by the Task Force on Immunity to COVID-19 (GTIC).
Since at least 2021, the team of Canadian researchers has been analyzing the blood of patients for traces of previous infections. This “seroprevalence” of SARS-CoV-2 antibodies increased from 5.1% before the Delta wave to 55.7% after five months of the Omicron wave.
Young adults (17 to 24 years old) were the most affected by this tsunami. No less than 65% of them were struck down by the disease.
The rate of infection decreases with age. It is 57% for those aged 25-39, 51% for those aged 40-59 and 31% for those over 60.
Spread over time, Omicron infections have been around 100,000 cases per day since December 15. This is “more than ten times the number of daily cases observed during the peaks of previous waves of SARS-CoV-2 for two years”, summarize the researchers in their report.
Not a seasonal virus
“This virus does not have a seasonal pattern like other respiratory viruses that we expect, when everyone returns to work or school in the fall,” notes the To have to the DD Catherine Hankins, co-chair of the GTIC. “The virus takes advantage of our behavior. […] Maybe it will become seasonal like other viruses of this type, in 5 or 10 years, I don’t know. At the moment, these are waves that depend a lot on what happens in terms of immunity. »
“Millions of Canadians now have hybrid immunity resulting from a combination of COVID-19 vaccines and infection. Unfortunately, new evidence suggests that most of these people remain at risk of reinfection with viruses of the Omicron variant lineage,” warned his colleague, Dr.r David Naylor, co-chair of the GTIC, in the written communication accompanying the report.
The blood test does not make it possible to estimate the prevalence of reinfections, but “it is obvious that there are a lot of reinfections, not only Delta-Omicron, but also Omicron-Omicron”, indicates the professor at the McGill University. “The virus continues to evolve, as we can see. We can’t wash our hands of it and say it’s over. »
This analysis ran until May 30, 2022. The number of infections today is therefore even higher.