Highly mutated COVID virus variant BA.2.86 showing up in multiple countries

A highly mutated variant of the virus behind COVID-19 has popped up in multiple countries, but scientists aren't yet sure whether it will help fuel a fall wave of infections or simply fizzle out.

BA.2.86 was deemed a variant under monitoring by the World Health Organization on Aug. 17. Though only a handful of samples exist, its emergence across several 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 stemmed from BA.2, an Omicron descendent that helped spark a wave of infections in spring 2022. So far, it's been identified at least six times in four countries, including Israel, Denmark, the U.S. and the U.K., all in the span of mere weeks. (There are no BA.2.86 detections yet in Canada, though scientists are actively monitoring this lineage, the Public Health Agency of Canada told CBC News on Monday.)

This Omicron offshoot has more than 30 mutations relative to BA.2 in its spike protein — the structures on the outside of each crown-like coronavirus that help it enter human cells — and is dramatically different in terms of its number of mutations when compared to either the original virus or the XBB strain targeted by upcoming fall vaccines. 

"It is unusual for [this virus] to change so significantly and develop 30 new mutations," said Morten Rasmussen, a senior researcher at Denmark's Statens Serum Institut (SSI), in a statement.

"The last time we saw such a big change was when [Omicron] appeared."

While that assessment may seem grim given how Omicron altered the course of the pandemic and drove infection rates to new heights, scientists have been quick to note that BA.2.86 may not live up to its predecessor.

"The most likely scenario is this variant is less transmissible than current dominant variants, and so never spreads widely," noted U.S.-based virologist and researcher Jesse Bloom in a series of social media posts discussing BA.2.86's evolution.

"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."

The significance of 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 extensive mutations in the virus's spike protein aren't entirely surprising, but rather a way for SARS-CoV-2 to continue evading the front-line defences of the human immune system. 

That could fuel more infections, even among people who've already been vaccinated or previously sick, but likely wouldn't lead to anything remotely close to the mortality seen early in the pandemic, Evans said.

"I think we have 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 at the University Health Network in Toronto. "Or will this end up taking off and being a dominant sublineage?"