New Omicron strains on the horizon could drive future COVID waves

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Omicron has completely taken over the pandemic, driving massive waves of COVID-19 in Canada and around the world in the past year. Now, scientists are trying to answer a crucial question — what could it throw at us next?

COVID levels reached new heights this year as Omicron and its highly contagious subvariants fought for dominance in the population, leading to relentless spread of the virus across the country. 

But as Omicron continues to mutate and produce new strains that have been shown to better evade immunity, with the potential to drive new COVID waves, scientists are warning that it may not be done with us yet. 

"The challenge is, we don't understand yet what this virus still has in store for us," Michael Osterholm, an epidemiologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told CBC News. 

"If you've got subvariants that can evade immune protection from previous infections and you've got waning immunity — that could set us up for a whole new set of circumstances." 

Global COVID levels have declined in recent weeks, with cases dropping 11 per cent and deaths declining by 18 per cent, according to the World Health Organization (WHO), but there are some troubling signs that rates of infection may soon pick up.

A recent spike in cases and hospitalizations in the U.K., and a recent rise of the virus in wastewater levels in Ontario and Saskatchewan have scientists bracing for potential fall and winter waves.

"There may be a giant wave from these variants, because they're going to spread," said Jeremy Kamil, a virologist and associate professor of microbiology and immunology at Louisiana State University. 

"But the possibility that they're going to cause hospitals to be overwhelmed is what I wanted to dial people back on because we're not seeing any signs of that."

Omicron has outlasted all other variants because of its ability to rapidly mutate and partially escape immunity, explaining why new subvariants have consistently emerged that have completely eclipsed other strains over the past year.

The WHO said Omicron subvariants now make up 99.9 per cent of sequenced cases globally — with BA.5 at 81 per cent, BA.4 at 8.1 per cent, BA.2.75 at 2.9 per cent, while other other Omicron subvariants are responsible for an estimated 7.8 per cent of sequenced cases.

The BA.5 subvariant remains the current dominant circulating strain in Canada, making up more than 85 per cent of cases in the latest federal data, but there are concerning new Omicron subvariants that scientists are now watching closely for signs of wider spread.

Two new subvariants, BA.2.75.2 and BQ.1.1, evolved from previous BA.2 and BA.5 strains and have mutations that have been shown to allow them to better evade immunity from vaccination and prior infection.