Why BA.2.86 Stands Out From Other COVID Variants

A highly mutated COVID-19 variant is raising the alarm among scientists, even though only two dozen cases have been reported worldwide.

BA.2.86, a new variant nicknamed “Pirola,” carries more than 30 mutations. This is the largest leap in viral evolution since Omicron, which caused a massive wave of cases when it first emerged in 2021.

According to a new risk assessment by the Centers for Disease Control and Prevention (CDC), BA.2.86 may be more likely to cause breakthrough infections in people who were previously infected or vaccinated, compared to other circulating variants.

However, the agency said there’s no evidence that the new variant will cause more severe disease than prior variants and that the upcoming updated COVID-19 booster shots should protect against BA.2.86. It’s also too soon to know whether the variant spreads much faster than others, the CDC said.

“It’s important to remember that we’re always going to see a march of variants,” Amesh Adalja, MD, an infectious disease expert at the Johns Hopkins Mailman School of Public Health, told Verywell.

“The key is not whether the new variants have transmission advantages. It’s ‘Do they have the ability to cause serious disease?’ It’s very unlikely that the variants will end up being able to cause serious disease at the scale that the virus once could because of all the immunity in the population and because of drugs like Paxlovid,” he said.

What Makes BA.2.86 Different?

Like the other current variants under monitoring, BA.2.86 is a version of Omicron, but it’s 34 mutations away from its relative BA.2.

“The sheer number shows you that this is something that’s heavily mutated—that it’s been through an evolutionary process. But the number doesn’t necessarily always translate into a significant behavior change,” Adalja said.

It’s most likely that those genetic changes in the virus will obscure the immune system’s ability to recognize the variant and attack it, even if someone has been vaccinated or previously infected, according to Eric Topol, MD, a leading COVID-19 researcher and the founder and director of the Scripps Research Translational Institute.

At a media briefing, Maria Van Kerkhove, a COVID-19 technical lead at the World Health Organization, said it’s difficult for scientists to know exactly how quickly BA.2.86 is spreading given the fall-off in viral testing and surveillance worldwide.

If BA.2.86 begins to circulate widely, the WHO could classify it as a “variant of concern,” Van Kerkhove said. That means the organization will give it a new Greek letter name to distinguish it from other Omicron variants.

“We felt this variant warrants closer monitoring because of the sheer volume of change we’ve seen,” Van Kerkhove said.

How Will Vaccines and Treatments Hold Up?

An updated version of the COVID-19 booster shot is coming soon. A panel of CDC advisors will meet on September 12 to review the safety and efficacy data for the new vaccine, and the shots could roll out soon after.

That vaccine targets Omicron variant XBB.1.5, which was widely circulating earlier this year. The newer variants that now dominate U.S. cases—including EG.5—are only a few mutations removed from XBB.1.5.

The CDC said it’s testing how well the vaccine neutralizes BA.2.86 in laboratory tests.

“It’s expected that the vaccine would not be very effective at blocking infection, but that’s not the job of the vaccine. The vaccine is not about blocking infection. It’s about blocking serious illness, hospitalization, and death,” Adalja said.

The CDC estimates that 97% of Americans have antibodies from prior infection or vaccination, and other immune cells likely provide long-term protection after antibodies wane. The vaccines will also likely still be able to target the parts of the spike protein that have remained the same.

“Even with a lot of mutations, there are a lot of spots in the virus that can be recognized by our immune system, and there are many shared mutations as well. There will be some protection from new vaccine booster as well as prior infections,” Rajendram Rajnarayanan, MSc, PhD, a researcher who tracks COVID-19 variants, told Verywell in an email.

The antiviral medication Paxlovid is designed to work regardless of any changes in the spike protein of the virus. While BA.2.86 carries some non-spike mutations, the parts of the virus that are key for making Paxlovid work are largely unchanged. That means the treatment should hold up against the new variant, Rajnarayanan said.

Because of a sharp decline in sequencing and laboratory testing, federal health agencies have much less visibility into how the virus is evolving and circulating. The dearth of centralized testing leaves it up to individuals to monitor their symptoms, get tested, and seek medical attention if they’re infected with COVID-19.

“If you’re in a virus hot spot, you know what to do: Get boosted as soon as the new booster is available,” Rajnarayanan said. “In the interim, all the non-pharmacological interventions that protected you before will protect you now as well.”

Taking steps like using air filtration devices and face masks, congregating with other people in well-ventilated spaces, staying home when you’re sick, and getting tested when you’ve been exposed or are experiencing symptoms can minimize the spread of the disease.