Two new subvariants of the Omicron strain of COVID-19 identified in recent months could fuel an increase in cases and hospitalizations in Canada through the fall and winter, infectious disease experts say.
Experts say the variants, labeled BQ.1.1 and BA.2.75, are spreading rapidly in several countries. BQ.1.1 is a subvariant of BA.5 and has also been identified in the UK where cases have spiked in recent weeks, while BA. 275, which the European Center for Disease Prevention and Control labeled a “relevant” variant in September, is spreading rapidly in India and Singapore.
The Omicron variant and its subvariants account for 99.9% of infections sequenced in the past 30 days, according to the World Health Organization. BA.5 continues to be the dominant strain, accounting for 80.8% of sequences, but other subvariants are emerging, including those in the BA.2 family, which includes BA.275, according to the organization.
Despite WHO’s latest epidemiological update released on Wednesday, which reported that global COVID-19 cases fell by 6% to 2.9 million infections, compared to last week, experts in infectious diseases in Canada are wary of the impact that these new strains could have in the provinces. , territories over the next few months.
WHAT THE EXPERTS SAY
“Basically we took all the protection off and let it rip all over the place,” Colin Furness, an epidemiologist and assistant professor at the University of Toronto’s Dalla Lana School of Public Health, told CTVNews.ca through a telephone. call.
“We’re creating a huge petri dish for biodiversity. Omicron has had every chance to mutate and vary, and it’s taking advantage of that,” he said.
Furness says the biggest problem is that there are an “infinite number” of other variants in development.
“So whether it’s those two or two others, what we’re really doing is we’re training Omicron to adapt to new circumstances…including a highly vaccinated population,” said said Furness.
“It develops an ability to be more immune,” he said.
Reduced or discontinued public health measures have created a window of opportunity for the Omicron variant to develop more immune evasion subvariants, Furness said. Fewer restrictions around the world means more cases, as millions of cases are still being recorded per day, and more cases means the virus has more opportunities to mutate, he explained.
Horacio Bach, assistant clinical professor in the Division of Infectious Diseases at the University of British Columbia, told CTVNews.ca via telephone interview that these subvariants have learned to change so that their hosts’ immune systems does not recognize them, causing the host to be more vulnerable to infection.
“We have a new variant that evades (the immune system) (and) the antibodies we have are not so good at preventing infection,” he said.
“These viruses multiply at such a high level because the physical safeguards are not in place. You give [the virus] the land is multiplying more and more, it is multiplying so fast,” he added.
The latest WHO epidemiological update also shows that cases in Europe are increasing. Reported infections increased by 8% compared to last week, and eleven countries in the region reported cases by 20% or more than the previous week, according to the organization.
What’s happening in Europe is what Canadians should be watching, Bach said.
WILL THE BIVALENT VACCINE BE EFFECTIVE AGAINST THESE VARIANTS?
The new bivalent vaccine that is now available in Canada is intended to target the Omicron variant with the original COVID-19 strain, Bach said. He says the bivalent vaccine may not work against future variants because it may become difficult for scientists developing vaccines to keep track of how many different variants emerge.
The effectiveness of the new bivalent vaccine against the new subvariants is unknown and the answer will emerge as breakthrough infections are tracked, Bach said.
A study, published in September in the New England Journal of Medicine, found that treatments used to improve symptoms of COVID-19 infection, including remdesivir, molnupiravir and nirmatrelvir, may also be effective against the undercurrent. -BA.275 variant, but drugs such as REGEN VOC may be less effective. These drugs are antiviral drugs and can work by stopping a virus from multiplying further in the body.
The researchers said it was still too early to tell whether either of these new subvariants could become the dominant strain of COVID-19 worldwide. The current dominant strain is BA.5, according to the WHO.
Another study, published in September in the scientific journal Cell Host and Microbe, found that the BA.275 subvariant has “improved knockout resistance” compared to the original B.A2 variant, meaning that it is more likely to evade the immune system.
Sameer Elsayed, professor of infectious diseases and microbiology at Western University, told CTVNews.ca via phone interview that new subvariants may be resistant to vaccines as well as current COVID-19 treatments.
“We are essentially chasing a moving target with our therapeutic and public health interventions,” he said.
DO WE KNOW HOW THIS WILL AFFECT FALL AND WINTER?
Currently, across Canada, there has been an uptick in reported hospitalizations for COVID-19, according to data released by the Public Health Agency of Canada (PHAC).
Between September 26 and October 3, data shows that hospitalizations fell from 4,557 to 5,070.
But the three infectious disease experts CTVNews.ca spoke to said it’s unclear exactly how the new subvariants might impact Canada.
However, with the abandonment of public health measures, Canadians should expect increased transmission, Elsayed said.
Moreover, the rise in cases in the UK “heralds” what is likely to happen in Canada a few months or weeks later, he said.
The concern about a possible increase in cases in the fall and winter, potentially fueled by new subvariants, is the risk to the elderly and those at high risk, he explained.
“Once you start hitting these highly resistant variants or sub-variants, there is 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 help before the fall would be assurances from governments that if cases spike, certain health measures would return, such as mask-wearing, Furness said.
Simply monitoring the number of cases will do nothing, if not coupled with actions, he explained.
“If the government was able to say, ‘Look, here’s our sewage scale, when it gets to that level, we put on masks’…otherwise you can look at hospitalizations, sewage, you can count absences from school … but it’s not going to do anything but take note of what’s going on,” he said.
“It’s not going to equip us to respond or to protect,” he said.
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