What you need to know about BA.2.86, the new ‘highly mutated’ COVID variant

As the United States enters the thick of respiratory virus season, a highly mutated COVID-19 variant called BA.2.86 is spreading and causing an increasing proportion of cases across the country.

Health officials have been closely monitoring BA.2.86, which is nicknamed "Pirola," since it was first reported in August. In recent weeks, the variant has slowly increased in the U.S. and now joins HV.1 and EG.5 as one of the most prevalent strains in the country.

Pirola initially made headlines this summer when it was detected in the U.S. because it has multiple genetic differences that set it apart from the previous versions of the virus, according to the U.S. Centers for Disease Control and Prevention.

BA.2.86 features more than 30 mutations compared to omicron XBB.1.5, which was the dominant variant for most of 2023 — it's also the strain targeted in the updated COVID-19 vaccine.

Last month, BA.2.86 barely made up 1% of cases in the U.S. but since early November, it has been driving a rising proportion of cases.

During a two-week period ending on Nov. 27, BA.2.86 accounted for nearly 9% of new COVID-19 infection in the U.S., according to the latest CDC data. However, these estimates are not exact, and the CDC said in a statement on Monday that BA.2.86 is actually projected to account for 5-15% of currently circulating variants.

The HV.1 subvariant is still the dominant strain in the U.S. right now, accounting for 31% of cases during the same period. After HV.1, the next most common variant was EG.5, aka Eris, which made up about 13% of cases, followed by JD.1.1, HK.3 and FL.1.5.1 or "Fornax."

Although the proportion of cases caused by BA.2.86 is going up, the CDC said that BA.2.86 does not appear to be driving increases in infections or hospitalizations in the U.S. at this time.

However, the variant has set off alarm bells in the past. In its initial risk assessment of BA.2.86 published in August, the CDC said it may be more capable of bypassing existing immunity from COVID-19 vaccines or prior infection, but there is no evidence it causes more severe illness.

Recent laboratory data suggest that Pirola may be less contagious and immune-evasive than scientists once feared, NBC News reported. The new booster appears to provide protection against BA.2.86 and other new variants, the CDC said.

It's unclear whether BA.2.86 will become dominant in the U.S. or cause a surge in infections, but there's no reason to panic, experts say. The public health risk posed by BA.2.86 is still low, per the CDC.

However, cases of COVID-19 are expected to increase this winter as they have during the last few years, and the holidays present more opportunities for the virus to spread.

Here's what experts know so far about BA.2.86, aka Pirola, the symptoms it's causing, its ability to spread and how to protect against it.

What is BA.2.86?

BA.2.86, which health experts dubbed “Pirola” on social media, was first detected in August in Israel and Denmark. It appears to have descended from the omicron BA.2 sublineage, which caused surges of the virus in early 2022, Andrew Pekosz, Ph.D., virologist at Johns Hopkins University, tells TODAY.com.

“The critical thing about this variant (BA.2.86) is that it has a whole host of mutations compared to some of the omicron variants that emerged about two years ago,” says Pekosz.

Early data show BA.2.86 has 34 more mutations in its spike protein than BA.2, which drove a COVID surge in 2022, and an additional 36 more mutations than omicron XBB.1.5, which rapidly took over the U.S. in early 2023, according to an Aug. 24 paper in The BMJ.

The mutations or changes in the virus sequence can affect how contagious a virus is, how well it responds to treatment and how severely it affects people, per the CDC.

“It represents a highly mutated form of SARS-CoV-2,” says Pekosz. In other words, BA.2.86 looks very different from the prevailing omicron XBB subvariants circulating.

What are the symptoms of BA.2.86?

At this time, it's not possible to know whether infection with BA.2.86 produces different symptoms from other variants, according to the CDC. "The case numbers are just too small," Pekosz says.

In its risk assessment of BA.2.86, the CDC said "there is no evidence that this variant is causing more severe illness," but like any variant, this could change as additional data comes in.

Common symptoms of other COVID-19 variants and subvariants include:

• Cough

• Sore throat

• Congestion

• Runny nose

• Sneezing

• Fatigue

• Headache

• Muscle aches

• Altered sense of smell

Based on what the CDC knows now about BA.2.86, existing tests and medications used to treat COVID-19 "appear to be effective with this variant," the agency said.

Where is BA.2.86 spreading?

The World Health Organization first classified BA.2.86 as a “variant under monitoring” on Aug. 17. Since then, BA.2.86 variant has been linked to over 6,300 cases in 47 countries, per the global virus database GISAID.

The countries reporting the highest number of cases are the United Kingdom, France, Sweden, the United States, Spain and Canada.

So far, there have been an estimated 540 cases reported in at least 30 states in the U.S. in either people or wastewater, per GISAID and the CDC. Although the first human cases were detected in August, BA.2.86 was likely circulating in the U.S. before the end of July 2023, the CDC said in an Oct. 27 report.

“The variant is probably spreading much more broadly than we’ve detected so far,” says Pekosz, adding that a lack of testing and sequencing is likely causing a delay in reporting.

Is BA.2.86 more transmissible?

Right now, it's too early to tell whether BA.2.86 is more transmissible than other variants, says Pekosz. "It's impossible to gauge anything about transmissibility or disease severity from that (small number of cases)," he adds.

However, based on what we know about the genetic sequence of BA.2.86 and the mutations in its spike protein, the variant will likely be able to escape preexisting immunity to COVID-19, Pekosz says.

The CDC echoed this in its BA.2.86 risk assessment, which stated that the variant could be more capable of causing infection in people who previously had COVID-19 or got vaccinated.

"Most of the mutations that we find in the spike protein are probably going to affect the ability of antibodies to bind and neutralize the virus," Pekosz adds.

In other words, BA.2.86 could escape not only immunity from vaccination or prior infection up until this point, but also vaccine-induced immunity from the coming fall vaccine, Pekosz adds.

In report published on Oct. 27., the CDC said more “real-world human outcome data” are needed to better understand the impacts of pre-existing immunity for BA.2.86.

"That's why this variant is very concerning to us from a scientific standpoint," he adds. "We need more sequences and cases to understand the variant's transmissibility."

According to the CDC, laboratories are currently researching the antibody neutralization of BA.2.86 to better understand how the immune system may interact with the virus.

Will BA.2.86 cause a surge in cases?

“We really don’t know if BA.2.86 will lead to increased numbers of cases,” Pekosz says. "The sequence can’t tell us how much disease the virus will cause, nor can it tell us how well it’s spreading," says Pekosz. Only time and more data will tell.

BA.2.86 did not drive the late summer surge in cases and hospitalizations in the U.S., experts told NBC News. This was likely driven by a combination of EG.5 and other omicron variants.

Pirola is not currently driving an increase in infections, though the proportion of cases it's causing is expected to rise in the coming months, the CDC said.

Nationwide, COVID hospitalizations appear to be trending upwards. In the last two weeks, average daily hospitalizations in the U.S. increased by 8.8%, according to an NBC News analysis. However, BA.2.86 does not appear to be responsible for a rise in hospitalizations, the CDC said.

CDC director Dr. Mandy Cohen said that cases are expected to increase this fall and winter.

How will BA.2.86 affect boosters this fall?

In September, federal health officials approved a new COVID-19 booster to roll out this fall. The updated vaccines for 2023-2024 are recommended by the CDC for everyone ages 6 months and older.

Doses are widely available at pharmacies, doctor’s offices and community clinics around the country. The CDC encourages everyone eligible to get at least one dose of the updated vaccine to protect against serious outcomes of COVID-19 this fall and winter.

However, uptake of the shot has been low so far, TODAY.com previously reported.

Right now, there are three vaccine options authorized by the FDA. These include two mRNA vaccines from Moderna and Pfizer for everyone ages 6 months and older, as well as a protein-based shot from Novavax for everyone ages 12 and older.

Manufacturers have reformulated the vaccines to protect against the omicron XBB.1.5 subvariant, which was the dominant strain circulating for most of 2023.

It has since been overtaken by other strains, but the updated COVID-19 vaccine appears to generate a strong immune response against BA.2.86, and experts anticipate the shots will provide cross-protection against newer strains circulating this winter, TODAY.com previously reported.

Moderna said that clinical trial data confirmed its new vaccine "showed an 8.7 to 11-fold increase in neutralizing antibodies against circulating variants, including BA.2.86."

The boosters are well-matched to the other strains currently making people sick, says Pekosz — and they will still be effective at reducing severe disease and hospitalization, per the CDC — so it's important for people to stay up to date with COVID vaccines.

The CDC is encouraging everyone eligible get the shot, especially those at higher risk, which includes people over the age of 65, those with underlying health conditions and the immunocompromised.

In addition to vaccination, people can protect themselves against COVID-19 by taking precautions such as wearing a mask, practicing social distancing, avoiding sick people and maintaining good hand hygiene.

This article was originally published on TODAY.com