A highly mutated variant of the virus behind COVID-19 has appeared in a number of countries, but scientists are still unsure if it will help fuel a wave of infections or just go away.
BA.2.86 was considered a variant under the control of the World Health Organization on August 17. Although only a few samples exist, its appearance on multiple continents since it was first identified in late July, coupled with its unusually high number of mutations, has put COVID watchers on high alert.
In the ever-growing SARS-CoV-2 family tree, BA.2.86 likely came from BA.2, a descendant of Omicron that helped trigger a wave of infections in the spring of 2022. So far, at least six times in four countries. , including Israel, Denmark, the US and the UK, all within the span of a few weeks. (There are no detections of BA.2.86 in Canada yet, although scientists are actively monitoring this lineage, the Public Health Agency of Canada told Breaking: on Monday.)
This offshoot of Omicron has more than 30 mutations relative to BA.2 in its spike protein, the crown-shaped structures on the outside of each coronavirus that help it enter human cells, and is dramatically different in terms of their number of mutations compared to the parent virus or the XBB strain targeted by upcoming fall vaccines.
“It’s unusual for [this virus] change so significantly and develop 30 new mutations,” said Morten Rasmussen, a senior researcher at the Statens Serum Institut (SSI) in Denmark, in a sentence.
“The last time we saw such a big change was when [Omicron] appeared.”
While that assessment may seem bleak given the way Omicron altered the course of the pandemic and pushed infection rates to new heights, the scientists were quick to point out that BA.2.86 may not measure up to its predecessor.
“The most likely scenario is that this variant is less transmissible than the current dominant variants, so it never spreads widely.” prominent US-based virologist and researcher Jesse Bloom in a series of social media posts about the evolution of BA.2.86.
“However, occasionally a variant has a sufficient combination of antigenic advantage and inherent transmissibility to spread widely. Whether this will happen can only be determined by waiting to see if more sequences are identified.”
Importance of ‘hard to predict’ mutations
The significance of the mutations is “sometimes difficult to predict,” agreed virologist David Evans, a professor in the departments of medical microbiology and immunology at the University of Alberta in Edmonton.
Evans said the extensive mutations in the virus’s spike protein are not entirely surprising, but rather a way that SARS-CoV-2 continues to evade the front-line defenses of the human immune system.
That could lead to more infections, even among people who’ve already been vaccinated or sick before, but it probably wouldn’t lead to anything remotely like the mortality seen early in the pandemic, Evans said.
“I think we need to be careful about the breathless discussion about every new strain and really look at the data first,” he added.
“Is this much ado about nothing?” questioned Dr. Isaac Bogoch, an infectious disease specialist with the University Health Network in Toronto. “Or will this end up taking off and being a dominant sublineage?”
The answers are still unclear.
Experts say signs including sewage testing and hospital admissions point to the start of a wave of COVID-19 in Canada before the fall.
A risk assessment from UK health officials He said it’s hard to know the combined effect of the large number of BA.2.86 mutations, though it probably means a “significant” change to the virus and how it works.
The only known UK case was identified in a patient who was tested at a London hospital on August 13, “with no recent travel history”, suggesting some level of community transmission.
The risk assessment there said it likely established international transmission as well, given the rapid appearance of samples in several countries.
US health officials are also monitoring BA.2.86, which once appeared in Michigan in an older adult with mild symptoms who was not hospitalized during his illness. according to US media reports.
Meanwhile, three other cases identified in Denmark were not linked, officials from that country said, adding that “it is still too early to say anything about the severity and contagion of the new variant.” Denmark’s SSI said it is also in the process of researching and culturing the virus variant to test it against antibodies.
None of the preliminary cases had symptoms “other than those typically seen” in the course of COVID-19, SSI Executive Vice President for Epidemiological Infectious Disease Preparedness Tyra Grove Krause said in a statement.
“We also have a high expectation that the vaccines, also with this variant, will provide good protection against serious diseases.”
Emerging variant amid a new wave of COVID
All of that is reassuring, Bogoch said, though he stressed that it’s still too early to tell what this variant has in store. “We know a lot about genetics,” he said, “but we don’t know a lot about transmissibility or clinical presentation.”
The variant is emerging as much of the world, including Canada, seems to be entering a fall COVID wave. Another Omicron subvariant, EG.5, is now dominant in the US and is increasing elsewhere as well, potentially leading to more infections.
But Bogoch emphasized that the The immunity landscape has changed dramatically over the years.since nearly everyone here in Canada has been exposed through vaccination, infection, or both, which means most variants are now less likely to cause large waves of serious illness.
“We’re dealing with a different Canada and a different world now,” he said.
