What are BA.2.75 and BQ 1.1? The two emerging COVID-19 subvariants raising concern among infectious disease experts

Two new subvariants of the Omicron strain of COVID-19 identified in recent months could fuel increased cases and hospitalizations in Canada through the fall and winter, infectious disease experts say.

Experts say the variants, labelled BQ.1.1 and BA.2.75, are spreading rapidly in multiple countries. BQ.1.1 is a subvariant of BA.5 and has also been identified in the U.K., where cases have ballooned in recent weeks, while BA.2.75, which the European Centre for Disease Prevention and Control labelled as a variant “of interest” in September, is spreading quickly in India and Singapore.

The Omicron variant and its subvariants account for 99.9 per cent of sequenced infections in the last 30 days, according to the World Health Organization. BA.5 continues to be the dominant strain, making up 80.8 per cent of sequences, but other subvariants are emerging, including those in the BA.2 family, which includes BA.2.75, the organization says.

Despite the WHO's latest epidemiological update released Wednesday, which reported that COVID-19 cases globally have declined six per cent to 2.9 million infections, compared to last week, infectious disease experts in Canada are wary about what impact these new strains could have across the provinces, territories over the coming months.

WHAT THE EXPERTS ARE SAYING

"Globally, we've pulled back all protections and we've let it rip just about everywhere," said Colin Furness, an epidemiologist and assistant professor at the University of Toronto’s Dalla Lana School of Public Health, told CTVNews.ca via a phone call.

"We're creating a massive petri dish for biodiversity. Omicron has been given every opportunity to mutate and to vary, and it's taking advantage of that," he said.

Furness says the bigger issue is that there’s an "infinite number" of other variants developing.

"So whether it's those two or another two, what we’re really doing is we're training Omicron to fit to new circumstances…including a highly vaccinated population," said Furness.

"It's developing a capacity to be more immune-escaping," he said.

Reduced or abandoned public health measures have created a window of opportunity for the Omicron variant to develop more immune-evading subvariants, said Furness. Less restrictions globally mean more cases, as millions of cases are still being recorded a day, and more cases means the virus has more opportunity to mutate, he explained.

Horacio Bach, a clinical assistant professor in the Division of Infectious Diseases at the University of British Columbia, told CTVNews.ca via a phone interview that these subvariants have learned to change in order for their hosts' immune system not to recognize them, causing the host to be more vulnerable to infection.

"We have a new variant that is escaping (the immune system) (and) the antibodies we have are not so good to prevent the infection," he said.

"These viruses are multiplying at such a high amount because the physical protections are not in place. You give [the virus] grounds to multiple more and more, they multiply so fast," he added.

The WHO's latest epidemiological update also shows cases in Europe are rising. Reported infections have increased eight per cent from last week, and eleven countries in the region have reported cases that are 20 per cent or higher than the previous week, according to the organization.

What's happening in Europe is what Canadians should be watching for, said Bach.

WILL THE BIVALENT VACCINE BE EFFECTIVE AGAINST THESE VARIANTS?

The new bivalent vaccine that is now available in Canada is meant to target the Omicron variant along with the original COVID-19 strain, said Bach. He says it is possible the bivalent vaccine may not work against future variants as it can become difficult for scientists developing vaccines to keep up with the amount of different variants that are emerging.

How effective the new bivalent vaccine will be against the new subvariants is unknown and the answer will emerge as breakthrough infections are tracked, said Bach.

A study, published in September in the New England Journal of Medicine, found that treatments used to improve symptoms of a COVID-19 infection, including remdesivir, molnupiravir, and nirmatrelvir may also be effective against the BA.2.75 subvariant, but such drugs as REGEN COV may be less effective. These drugs are antiviral medications, and can work by preventing a virus from multiplying further within the body.

The researchers said it’s still too early to tell whether either of these new subvariants could become the dominant COVID-19 strain globally The current dominant strain is BA.5, according to the WHO.

Another study, published in September in scientific journal Cell Host and Microbe, found the BA.2.75 subvariant has "enhanced neutralization resistance" over the original B.A2 variant, meaning it’s more likely to evade the immune system.

Sameer Elsayed, a professor of infectious diseases and microbiology at Western University, told CTVNews.ca via a phone interview that new subvariants could be resistant toward vaccines as well as current COVID-19 treatments.

"We’re basically chasing a moving target with our therapeutics and public health interventions," he said.

DO WE KNOW HOW THIS WILL IMPACT THE FALL AND WINTER?

Currently across Canada, there has been a slight uptick in reported COVID-19 hospitalizations, according to data published by the Public Health Agency of Canada (PHAC).

Between Sept. 26 and Oct. 3, the data shows hospitalizations increased from 4,557 to 5,070.

But all three infectious disease experts CTVNews.ca spoke to said it’s uncertain exactly how the new subvariants may impact Canada.

However, with the dropped public health measures, Canadians should expect increased transmission, said Elsayed.

As well, the cases rising in the United Kingdom is “heralding” what will likely occur in Canada a few months or weeks later, he said.

The concern with a possible increase of cases into the fall and winter, potentially fuelled by new subvariants, is the risk toward older people and those who are high-risk, he explained.

“Once you start hitting these very resistant variants or subvariants, there’s a risk that [older people] won't have very good immunity…and then we won’t have good treatments that work well,” he said.

What would be useful heading into the fall is assurances from governments that if cases explode, some health measures would return, like mask-wearing, said Furness.

Simply surveilling the number of cases will do nothing, if it’s not coupled with action, he explained.

“If the government were able to say, ‘Look, here’s our wastewater scale, when it gets to this level we put on masks’....otherwise you can watch hospitalizations, wastewater, you can count absences from school…but that’s not going to do anything but take note of what’s happening,” he said.

“It’s not going to equip us to respond or to protect,” he said.