Majority of Canadians have now caught COVID — so what does that mean for the future? 

The majority of Canadians have caught COVID-19 since Omicron and its highly contagious subvariants triggered enormous waves of infection this year — with new estimates suggesting almost two-thirds of the population have had it.

Researchers in British Columbia analyzed close to 14,000 blood samples in the Lower Mainland throughout the pandemic to track antibody levels in the general population, and found a massive shift in the number of infections in the past few months.

The B.C. Centre for Disease Control and Prevention (BCCDC) and University of British Columbia team previously found almost half previously had COVID as of April, but their new data suggests that number continued to skyrocket into the spring and summer.

The findings were published in a preprint study co-authored by B.C. Provincial Health Officer Dr. Bonnie Henry this week, which has not yet been peer reviewed, that found more than 60 per cent of the overall population had antibodies from prior infection by August. 

"It really shows us the change that we saw, particularly when Omicron came … what we're seeing now is that people may have an infection on top of being vaccinated and that has led to a level of potential immunity," Henry told CBC News. 

"We don't know how much antibody you actually have to have to be protected, but it does give us a good sense that we have a very high level of population protection against this virus now." 

The data is also broken down by age groups and found the highest level of infections by far were in Canadians under 19, with at least 70 to 80 per cent of youth now showing evidence of prior infection — compared to about two-thirds as of April.

But adults are also seeing an increase in COVID, with at least 60 to 70 per cent of those aged 20 to 59 years old now showing evidence of previous infection, and about 40 per cent of Canadians over 60 — up from just 15 per cent as of March. 

"What we observed is that children currently appear to be the most infected and least vaccinated, whereas elderly adults remain the most vaccinated and least infected," said Dr. Danuta Skowronski, epidemiology lead at the BCCDC and co-author of the preprint. 

"The main takeaway for me and my colleagues from this most recent update is that the elderly are particularly now reliant on vaccine-induced protection alone as we enter the fall of 2022, and so they should remain the priority for additional booster doses." 

The data shows huge surges of infections after Omicron landed in Canada in late 2021 and raises new questions about what that level of population immunity means for the future as updated vaccines begin to roll out across the country targeting the highly contagious strain. 

"We're in a completely different place than we were even a year ago, but particularly from the beginning of the pandemic," Henry said. 

"So what that tells me is that there are very few people now who are at extreme risk like they were early on when we didn't have any immunity at all in anybody — and we need to pay attention to that." 

The research also coincides with national data from the federal government's COVID-19 Immunity Task Force that suggests close to 60 per cent of Canadians from coast to coast had been previously infected up to July — a massive increase over the past year.