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Scientists are closely monitoring new Omicron subvariants that can evade immunity better than previous strains.
The new sub-variants have the potential to cause future waves, but protection from severe COVID-19 has so far held up in the population.
Updated bivalent boosters and the population’s immunity to vaccination and previous infection will be put to the test this fall and winter.
Omicron has completely taken over the pandemic and has caused massive waves of COVID-19 in Canada and around the world over the past year. Now scientists are trying to answer a crucial question: What could it get us next?
COVID levels reached new heights this year as Omicron and its highly contagious subvariants battled 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 trigger new waves of COVID, scientists warn it may not be done with us yet.
“The challenge is that we don’t yet understand what this virus 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 have subvariants that can evade immune protection against previous infections and you have declining immunity — that could put us in front of a whole new set of conditions.”
Global COVID levels have fallen in recent weeks, with cases falling 11 percent and deaths falling 18 percent, according to the World Health Organisation (WHO), but there are some disturbing signs that the infection rate could increase soon.
A recent peak in UK cases and hospitalizationsand a recent rise of the virus in wastewater levels in Ontario and Saskatchewan let scientists brace themselves for possible fall and winter waves.
“There could be a giant wave of these variants as they start to spread,” said Jeremy Kamil, a virologist and associate professor of microbiology and immunology at Louisiana State University.
“But the possibility of them overwhelming hospitals is what I wanted to call people back on because we’re not seeing any signs of that.”
New Omicron Subvariants Raise Concern
Omicron has outlasted all other variants due to its ability to mutate quickly and partially escape immunity, which explains why new sub-variants have consistently emerged that have completely eclipsed other strains in the past year.
The WHO mentioned Omicron subvariants now make up 99.9 percent of sequenced cases worldwide – with BA.5 at 81 percent, BA.4 at 8.1 percent, BA.2.75 at 2.9 percent, while other Omicron subvariants subvariants are responsible for an estimated 7.8 percent of consecutive cases.
The BA.5 subvariant remains the current dominant circulating strain in Canada, accounting for more than 85 percent of cases in the last federal databut there are new Omicron subvariants that scientists are now watching closely for signs of wider distribution.
Two new sub-variants, BA.2.75.2 and BQ.1.1has evolved from prior BA.2 and BA.5 strains and has mutations shown to better evade immunity from vaccination and prior infection.
A new preprint laboratory study from Sweden, which has not been peer-reviewed, found that the Omicron subvariant BA.2.75.2 had a “profound antibody escape” against immunity from previous infection, suggesting it can “effectively circumvent antibody immunity in the population” “.
BA.2.75.2 and BQ.1.1 were also found to be “the most antibody-evasive” strains tested, “much higher than BA.5” in a new preprint lab study from China that has not been peer-reviewed – looking specifically at protection against the Sinovac vaccine.
Despite the fact that these two new sub-variants are only one fraction of a percent of recently sequenced cases worldwide, virologists are concerned they could potentially trigger future waves of COVID, especially given their mutations involved.
Tom Peacock, a virologist at Imperial College London, said they may trigger future spikes because they are structurally different enough from previous wave-causing strains and can also partially escape previous immunity to vaccination and infection.
“Several of these genera grow quite quickly — this includes BA.2.75.2 and BQ.1.1,” he told CBC News. “These combined traits suggest they could trigger the next wave of COVID, both regionally and globally.”
If these new sub-variants push up COVID levels again in the future, the biggest unanswered question we face right now is, how will our immune defenses against vaccination and previous infection withstand what Omicron faces next?
“There is clearly a horse race going on between these variants to replace each other,” Kamil said. “Whether that means that in cases these variants will really cause a massive massive wave and spike, we don’t know and it’s too early to say — but it seems possible.”
‘Hybrid immunity’ being tested
While vaccine effectiveness against serious consequences has held up well, two-dose protection against Omicron infection dropped dramatically compared to previous variants — dropping to just 36 percent in December and rising to 61 percent with a booster, according to a new Ontario study published in JAMA.
That hit our population immunity to vaccination against Omicron infection underlined the need for boosters earlier this year, and it made us highly susceptible to the Omicron subvariant-driven waves that have since ripped through the population.
New national data of the federal COVID-19 Immunity Task Force found nearly two-thirds of Canadian adults are infectedlargely since Omicron first popped up last December — with younger adults bearing the brunt of more than 73 percent.
“Canada had very limited transmission of the virus through the population for nearly the first two years of the pandemic,” said Dr. Tim Evans, director of the School of Population and Global Health at McGill University and executive director of the task force. .
“Omicron changed all that, and none of us really knew how much it would change that.”
But that level of immunity in the population to vaccination and infection can have a silver lining as we head into the fall and winter — if it lasts.
A new Canadian study published in The Lancet who analyzed protection against both vaccination and previous infection found that those with combined hybrid immunity fared better against future COVID infections.
The study found that two doses of a COVID-19 vaccine plus recovery from an Omicron infection provided protection equivalent to three doses, and those with protection against both vaccination and infection may be better protected against future reinfections.
dr. Gaston De Serres, an epidemiologist at the Quebec National Institute of Public Health and co-author of the study, said that while vaccination offers significant protection against infection and hospitalization, the study demonstrates hybrid immunity. gives a head start.
“You do have some protection [with vaccination]but it’s clear that being infected adds a lot,” he said, pointing out that infections can still be serious and should be avoided. “This concept of hybrid immunity being stronger and more efficient is pretty well demonstrated here, I think. .”
But given that only about 40 percent of Canadians over the age of 60 were found to have had COVID-19, according to the national immunity dataleaving much of the population still more vulnerable to infection in the future, especially with newer strains.
“Omicron hasn’t affected everyone equally,” Evans said. “We still have a significant minority of Canadians who are not infected and they cluster in the older age groups where the risk of adverse effects from [the virus] are the biggest.”
Bivalent vaccines may reduce risk
Canada recently launched a updated bivalent COVID-19 vaccine which targets both the original virus and the original Omicron variant BA.1, but whether it will help prevent future waves is unclear.
“In terms of the duration of that protection and how it will apply to future variants – unfortunately we don’t have a clear answer to that,” said De Serres.
“We think the bivalent vaccines will help reduce the risk of infections with the new viruses, but again, it’s not like it will be as effective as the vaccine was before the arrival of Omicron.”
The new dose does not directly target dominant subvariants BA.4 and BA.5, which US has approved an updated recording for this month. Pfizer and Moderna both filed for Health Canada approval earlier this month for their BA.4-BA.5 targeted vaccines.
In the meantime, public health officials across the country are prioritize additional boosters of bivalent vaccines for vulnerable groups, including older Canadians and the immunocompromised, in hopes of providing better immune protection for the fall.
“It remains to be seen,” Evans said, regarding how well the population’s immunity will hold up. “I think the trend lines are going in the right direction, and that’s clearly a function of people having good protection, either through vaccination or vaccination and infection.”
How long the protection against infection and serious illness lasts, even with updated bivalent vaccines and high levels of immunity in the population, is unclear, but it will likely be put to the test this fall and winter.
“We don’t know what else is going to happen. We could go on like this for a few more months and then suddenly see a big change,” Osterholm said. “The immunity we have will certainly provide a roadblock to that — but how good it is, we don’t know.”