Thousands in Ontario catching COVID twice: Why reinfections are now more common than you’d think

As a scientist and a mom, Julie Lajoie was frustrated" to recently discover her daughter appeared to have been reinfected with COVID, the dreaded two lines showing up on a rapid test for the second time in only about a month.

I am seeing my oldest, who is normally full of energy, asking for a nap and slowly fighting this virus - again," Lajoie, a research associate at the University of Manitoba who holds a PhD in virology and immunology, said in an email, having lost her voice due to her own COVID infection.

More than two years into the pandemic, Lajoie's little girl joins a growing number of people around the world who have contracted the disease twice, from Britain's Prince Charles to White House press secretary Jen Psaki, whose second positive test since October made headlines as she was forced to cancel an upcoming trip to Europe with President Joe Biden.

Reinfections were once thought to be very rare. But that changed with the arrival of Omicron, which is different enough from the original virus that causes COVID and other variants to evade some existing immunity.

Now, with cases soaring in the midst of a sixth wave, documented reinfections of COVID-19 are rising again, according to Public Health Ontario data, with over 10,000 total reinfections since November 2020. The agency warns that the risk of reinfection with the more contagious BA.2 subvariant, which is now dominant globally, is high."

Experts say while getting Omicron (also known as BA.1) after an earlier variant such as Delta, Alpha, or the original version, is more common, you should have some immunity to BA.2 if you were sick earlier this winter, and some protection against getting BA.2 if you've just had it. But a lot depends on your individual immune system and vaccination status. There's still a lot scientists don't know - and don't be tempted to skip that booster shot.

It's not that necessarily all of a sudden BA.2 is more capable of causing reinfections, it's that there's more opportunities for reinfections to occur," said Angela Rasmussen, a research scientist and adjunct professor at the University of Saskatchewan, because we're opening up."

With protective measures such as masking in most indoor public spaces and vaccine certificates now dropped in Ontario and most other provinces, there are just more opportunities for the virus to find people, she said. The same is true of Britain where reinfections, tracked publicly by the U.K. Health Security Agency (UKHSA), and cases in general, are once again rising.

But, Rasmussen said, it's not clear whether these are reinfections from people who had Omicron and then BA.2 or who had an earlier variant.

As for whether the average person who recently got Omicron or BA.2 can expect to be reinfected, Rasmussen said it depends on a number of factors including their vaccination status and immune system.

It's expected that those who've had a prior strain and/or been vaccinated and then get BA.1 would expand their antibody repertoire" with this new infection. A second time around should, in general, also be more mild. That doesn't mean though, that they shouldn't get their third shot if they've had Omicron.

There's certainly a lot of evidence that also indicates that getting a booster shot of the vaccine does really significantly improve protection, including against infection with BA.1 and presumably also BA.2," Rasmussen added.

Public Health Ontario began tracking weekly reported reinfections in its epidemiological summaries in late May 2021. These numbers were fairly flat, at under 20 a week, until the Omicron surge of December 2021, when they rose to a high of 806 the last week of January, before falling and plateauing in the 200s. They are now on the uptick again, with 326 reported for the week ending March 26. The latest summary includes a cumulative total since November 2020, listing just over 10,000 reinfections during that time.

The province started including reinfections that occur at least 90 days after a previous infection, as well as laboratory confirmed reinfections, in mid-January.

That means Lajoie's daughter's case wouldn't have even been officially counted if she lived in Ontario.

But, before the family came out of isolation the first time, they rapid tested twice, 24 hours apart, and were all negative. There are now three confirmed cases by rapid tests in her daughter's daycare cohort, Lajoie said, and she believes reinfection is becoming more common.

The scientific research on reinfections is happening in real time.

A February preprint study from Denmark concluded that reinfection with BA.2 shortly after BA.1 was possible, yet rare, Lajoie noted. But now there are little to no public health measures, masking, or contact tracing, so we are hearing of more cases."

Another preprint study out of the U.S. published online in March that analyzed over 300,000 cases of COVID, found that reinfections increased from less than 500 per month through November 2021, to over 4,000 per month in January.

We are over three months of the December peak so we will see more Omicron reinfections, at what rate we don't know," said Lajoie. The narrative" that one COVID infection means guaranteed long-lasting immunity needs to change as it's no longer accurate, she added.

If people were more aware of this maybe they would be more cautious."

At the beginning of the pandemic, herd immunity was one controversial strategy for dealing with the disease. But it's now looking like immunity from previous infection wanes, lasting a few months, rather than years, said Dr. Charu Kaushic, a professor at the McMaster University School of Medicine, and a member of Canada's COVID-19 Immunity Task Force. Plus, the virus itself has mutated.

It would be possible if it was one virus that never changed and the more people got it the more immunity you got in the population, but that's not how this has turned out to be," she said.

With that in mind, the focus now should be on making sure people around the world have access to vaccines to prevent new variants that can escape existing immunity, like Omicron, from developing.

Wherever there are lots and lots of infections and the more the virus replicates, the more likely it's going to mutate and more variants will come out," said Kaushic.

Globally, there's still a lot of susceptible people that the virus can pass through and eventually new variants will emerge that can get around our vaccines, which is why it's still causing a problem for us," added Rasmussen.

And on an individual level, the best thing people can do, regardless of whether they've had COVID already, is get a third shot of the vaccine, all three experts agreed. According to the Ontario Science Table, only 60 per cent of people 18 and up have received a third dose. The national figure is even lower, just 56 per cent.

The booster as this point really shouldn't be regarded as something optional that you get to make yourself feel better, there is really strong data supporting its use against Omicron," Rasmussen said.

May Warren is a Toronto-based breaking news reporter for the Star. Follow her on Twitter: @maywarren11