The majority of Canadians have already caught COVID-19: what impact for the future?

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The majority of Canadians have already caught COVID-19: what impact for the future?

70 to 80% of Canadians under the age of 19 have already been infected with the virus causing COVID-19, according to a study.

The majority of Canadians have been infected by SARS-CoV-2, the virus that causes COVID-19, since the arrival of Omicron and its highly transmissible subvariants, which caused a huge spike in the rate of infection. infection in Canada this year. According to recent estimates, three quarters of the population have already had COVID-19.

In British Columbia, researchers have analyzed nearly 14,000 blood samples from residents of the Fraser Valley since the start of the pandemic, in order to track antibody levels in the general population. They noted a significant change in the infection rate over the past few months.

Last April, the team of researchers from the British Columbia Center for Disease Control (BCCDC) and the University of British Columbia (UBC) estimated that about half of this population had already been infected with COVID-19. The latest data shows that this rate spiked in early spring and into the summer.

Those findings were made public in a pre-published study this week, co-authored by British Columbia's Chief Medical Officer of Health, Dr. Bonnie Henry. This study, which has not yet been peer-reviewed, concludes that more than 60% of the general population has antibodies to SARS-CoV-2 due to prior infection.


Dr. Bonnie Henry is co-author of the study which has not yet been peer reviewed.

It really demonstrates the change that's been happening, especially with the arrival of Omicron […] What we're seeing is that people can get infected even when they're vaccinated and that possibly causes some immunity, says Dr. Henry.

We don't know the level of antibodies needed to be protected, adds Dr. Henry, but it shows rather well that the level of protection of the population against this virus is now very high.

The data, which is also grouped by age group, shows that Canadians under the age of 19 have the highest rate of infection, 70-80% of them having been previously infected. This rate was around 60% in April.

The rate of pre-infection is also on the rise in the adult population:60-70% of people aged 20-59 show signs of pre-infection. This rate is around 40% for people over 60, an increase of 15% compared to March.

During the first wave of COVID-19, many seniors living in care homes died.

We find that children are the most infected and the least vaccinated, while older people are always the most vaccinated and the least infected, says Dr. Danuta Skowronski, epidemiologist at BCCDC and co-author of the study. .

The most important conclusion I take from this latest data, adds Dr. Skowronski, is that older adults are particularly dependent on vaccine protection as the fall of 2022 arrives and that they should therefore continue to be prioritized for booster doses of the vaccine.

The data demonstrate a significant increase in infections after the arrival of the Omicron variant in Canada at the end of 2021. This begs the question of the impact of this important immunity rate for the future as vaccines targeting the newer, more contagious variants are administered. across Canada.

Everything has changed over the past year and even more since the start of the pandemic, says Dr. Bonnie Henry. It tells me that now very few people are at such extreme [health] risk as was the case when no one had immunity to the virus. We must take this information into account in our reflections.

Pfizer's new COVID-19 vaccine, approved by the European Medicines Agency on Monday, targets Omicron BA.4 and BA.5 subvariants.

This research report coincides with data from the Federal Task Force on COVID-19 Immunity stating that in July almost 60% of all Canadians had already been infected with the virus, a very significant increase compared to the previous year.

On Monday, the Task Force released data from Canadian Blood Services showing an increase in infections of nearly more than 30,000 among CCanadians who donated blood in July, a jump from 50 to 54%, all ages combined.

That's good news and bad news, notes Dr David Naylor, who led the federal inquiry into Canada's response to the SARS outbreak in 2003 and is now Co-Chair of the Federal COVID-19 Immunity Task Force.

In July , nearly 60% of Canadians had already been infected with the virus, according to data from the Federal Task Force on Immunity to COVID-19.

The good news is that there is significant latent immunity from vaccination and previous infections, says Dr. Naylor, adding that this hybrid immunity should limit the impact of COVID-19 as classes and in-person work resume.

This growth in the rate of hybrid immunity is a relative blessing, says Dr. Naylor. This demonstrates that the virus is continuing to spread, meaning there are more people with “long COVID” symptoms. which are of varying duration and severity.

Dr. #x27;bed in bed for several days before recovering and as COVID-19 continues to lead to the death of a significant number of vulnerable people, a number that is expected to increase this fall and winter.

The impact of this shift in Canadians' immunity on possible new waves of COVID-19 remains to be determined, but for many vulnerable people, infection with the virus poses serious risks. These people continue to be at the top of the list of future vaccination campaigns.

We know who the people most vulnerable to the virus are, says Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital. Older people and people with already compromised immunity from other illnesses are obviously at greater risk. He adds that low-income people and members of racialized communities are also disproportionately affected by the virus.

We now have a baseline level of immunity in the population that protects everyone, concludes Dr. Bonnie Henry, including people who do not develop good immunity to the virus even after being vaccinated. The number of people who are at risk of becoming seriously ill from COVID-19 is therefore greatly reduced.

Giving a dose of the vaccine that targets the Omicron variant to a An already well-immunized population helps create a community with hybrid immunity, which makes us much better prepared for potential future waves of infections, says Dr. Skowronski.

New bivalent vaccines target both the original SARS-CoV-2 virus and the Omicron BA.1 variant.

For his part, Dr Bogoch is cautiously optimistic about new bivalent vaccines and their long-term protection against future waves of the virus . He adds that these vaccines are not yet proven.

That said, I prefer a vaccine that more closely targets the circulating virus, but I don't know if that protection will be long-lasting, he says. Frankly, even the old vaccine protects against serious infection, hospitalization and death for a very long time. It's true, it's proven, it's beautiful.

Dr. Henry says vaccination has been a game-changer in Canada and despite the high rate of infection and transmission of the virus, the situation is not at all the same.

I believe this is a difficult concept to understand because we have long told people that having COVID-19 is very, very serious, especially for immunocompromised people, she says. Now, since there are so many people vaccinated and many have this hybrid immunity, the risk is really reduced for everyone.

With the information from Adam Miller

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