By Sumathi Reddy

Scientists have their eye on a different variant than the XBB variants, such as EG.5, that are driving the summer Covid-19 bump.

BA.2.86—dubbed “pirola” by a group of scientists on social media who name notable variants—has been detected in only about a dozen people but it has surfaced in all corners of the world. What’s troubling about this variant, scientists say, is that it contains more than 30 mutations on the spike protein, which is what helps the virus enter cells and cause an infection. This means it might be able to evade current vaccines and previous infections more easily, and it likely won’t be a great match with the fall booster expected to be approved soon.

“It’s drastically different” than the dominant variants circulating now, says Katelyn Jetelina, a scientific adviser to the Centers for Disease Control and Prevention and author of the “Your Local Epidemiologist” newsletter.

It’s unclear whether the variant will result in different or more severe symptoms.

What we know about BA.2.86

Positive cases of BA.2.86 have been reported in the U.S., Denmark, Israel, South Africa, Portugal and the U.K. The cases include people who haven’t traveled recently, suggesting that there is community transmission. It’s also been detected in wastewater in the U.S., according to the CDC, and in Switzerland and Thailand.

What’s unknown is how transmissible the variant is and whether it will spread widely or fizzle out like many other variants. Another important, outstanding question is whether it causes more severe disease.

Jetelina says she hypothesizes that if the variant spreads widely, it would be able to escape the neutralizing antibodies we have from vaccines and previous infections, making it easier to get infected, but might not be as successful with our immune system’s second line of defense, the T-cells, which protect against severe disease.

Scientists say treatments such as the antiviral Paxlovid should still remain effective even with such a highly mutated virus because they target a different part of the virus, not the spike. Rapid antigen tests, often used to test for Covid-19 at home, also should be able to detect the new variant, the CDC said last week.

In a risk assessment released Aug. 23, the CDC said scientists are evaluating the effectiveness of the fall Covid-19 booster, expected to roll out in September, and the new variant.

Jesse Bloom, a virologist and professor at Fred Hutchinson Cancer Center in Seattle, says transmission is likely happening because multiple sequences of the variant have been identified in different countries.

“Certainly, it’s probably in more places than it’s been identified so far because surveillance is incomplete,” says Bloom.

Why this Covid variant is worth watching

Bloom says the evolutionary jump of BA.2.86 is similar to that of the original Omicron, which burst onto the scene in the winter of 2021 resulting in a spike in infections.

But he and other scientists, including the CDC, note that the Covid-19 landscape is different now as almost everyone has some immunity to Covid-19 from either a previous infection and vaccines.

Scientists don’t know where the variant originated. Because it contains so many mutations, they speculate it developed over months in an immunocompromised person with a chronic infection.

“It’s probably been evolving for quite some time,” says T. Ryan Gregory, an evolutionary biologist and professor at University of Guelph in Ontario. Gregory says it isn’t clear whether it’s taking off as a variant the way Omicron did.

With surveillance efforts reduced, the new variant could be common in a locale without being noticed, says Gregory.

Even if BA.2.86 doesn’t spread widely, it’s an important reminder that vastly different strains can surface out of nowhere, says Justin Lessler, a professor of epidemiology at the University of North Carolina at Chapel Hill.

Lessler says the fact that the locations where the variant has been identified haven’t experienced large surges in cases is a hopeful sign that the strain might not be proliferating rapidly. “But that doesn’t mean it can’t mutate to be able to spread quickly at some point,” he notes.

Some public health experts caution against reading too much into the new variant.

“We don’t want to be sounding alarm bells over a variant that is just as likely to die out as it is to become the next big thing,” says David Dowdy, a professor of epidemiology at Johns Hopkins Bloomberg School of Public Health. “If we did that for every single variant we’d be sounding alarm bells every single day.”