JN.1, the WHO’s newest ‘variant of interest,’ has spiked COVID wastewater levels to all-time highs in some countries. What you need to know about the ‘Pirola’ offshoot

The global health watchdog on Tuesday promoted JN.1—an Omicron spawn experts flagged this summer for its unusually large number of mutations—to a “variant of interest.” It’s second only in alert level to a “variant of concern,” which Omicron, Delta, and Alpha were until the organization removed their status.

How dangerous is JN.1, how likely are you to get it, and could it derail your holiday plans? Here’s what you need to know, according to the experts Fortune spoke with.

What in the heck does JN.1 even mean?

JN.1 is yet another Omicron offshoot, technically. It evolved from BA.2.86, a COVID variant that caught the attention of experts this summer because of its large number of mutations compared to the original Omicron: a whopping 30 or more, depending on how you count them. BA.2.86 was—and still is—the most genetically distinct COVID variant to have evolved since Omicron, which burst onto the global scene in early 2022. It was so distinct, many experts said, that it warranted a new Greek letter from the World Health Organization.

Along with BA.2.86’s laundry list of mutations came the ability for the virus to evade immunity and infect cells with increasing ease. Variant trackers dubbed BA.2.86 “Pirola”—after an asteroid—as a nod to their belief that the new variant, or one of its offspring, may eventually warrant a new Greek letter: presumably Pi or Rho.

BA.2.86 failed to take off in the way it seemed poised to, though it managed to show strong growth in some regions of the world. As early as August, however, experts warned that while BA.2.86 may not be the black swan “Omicron event” some thought it was, one of its descendents could be.

Enter JN.1. While the letters make it sound like it’s coming from left field, it’s really not. It’s BA.2.86 plus one additional major mutation that makes a lot of difference: L455S, which boosts its ability to evade antibodies from prior infection and vaccination. 

Technically, JN.1 is BA.2.86.1.1, but the naming system for COVID variants calls for them to truncate after three additional sets of numbers and periods. So, BA.2.86.1.1 “rolled over” to JN.1.

What are the symptoms of JN.1?

It’s too early to tell if the symptoms of JN.1 differ from typical Omicron symptoms. So far, there’s not much evidence that this is the case, though there are reports of increased diarrhea that may or may not be tied to the variant.

Is JN.1 more dangerous than other Omicron variants?

It’s also too early to say. Hospitalizations are rising in some areas like New York City. But rising hospitalizations could be the result of waning population immunity, at least in part. And other variants undoubtedly contribute to hospitalizations and deaths.

In the U.S., hospitalizations were slowly rising as of Dec. 9, while deaths were holding steady, according to the latest data made available by the U.S. Centers for Disease Control and Prevention.

Do COVID vaccines work against JN.1?

Yes. They’re thought to provide good protection against severe illness, hospitalization, and death.

“For those interested in gaining immunity with less risk than COVID-19 illness, the monovalent (XBB) vaccine released a few months ago provides substantial immune response to the JN.1 variant,” Ray said. “Like prior variants that have gained against others, it’s not clear whether JN.1 will result in significantly higher rates of severe COVID-19 or long COVID, but I’m seeing a lot of respiratory illness due to COVID-19, RSV, and influenza in my hospital patients. So it makes sense to take reasonable precautions in this respiratory virus season.”

Should I be masking again due to JN.1?

It would be wise to, many experts say. Ray recommends “wearing an effective respirator in public spaces, especially indoors, when it doesn’t interfere with essential tasks.”

“Not a bad way to keep your face warm, too,” he added.

Does Paxlovid work against JN.1?

Yes, though experts caution that those who are prescribed Paxlovid and stop taking the pill midway through due to its off-putting metallic taste could be contributing to the virus’ potential evolution around the antiviral, rendering it ineffective.

Do at-home COVID tests still work with JN.1?

Yes, though they were never completely accurate. Many people test too early or their infection or too late. At both times, viral loads may not be significant enough to turn the test positive. If you have symptoms but test negative, wait another couple of days and test again, experts recommend.

The WHO just declared JN.1 a ‘variant of interest.’ What does that mean?

When the WHO declares a COVID strain a variant of interest, it’s calling for vigilance and increased sequencing and monitoring by health authorities in countries across the globe. 

In a practical sense, and for the average person, “it doesn’t change anything,” Dr. Ryan Gregory, a biology professor at the University of Guelph in Ontario, Canada, told Fortune. For over a year, Gregory and a team of “variant trackers” have worked to offer up “street names” for COVID variants, in a bid to better communicate the evolving Omicron threat to the public.

“I do think that, in some ways, it’s good that they’re indicating this is still evolving and still worth monitoring,” he added.

Just how fast is JN.1 spreading?

With sequencing of COVID viral samples at a near all-time low, it’s hard to say exactly. We do know, however, that JN.1 “appears to be out-competing other circulating variants worldwide, including its recent ancestor BA.2.86 and siblings.” That’s according to Dr. Stuart Ray, vice chair of medicine for data integrity and analytics at Johns Hopkins’ Department of Medicine.

In what countries is JN.1 causing, or contributing to, a record level of COVID spread?

Countries that are currently seeing all-time highs of COVID in wastewater—higher than even the Omicron spike of early 2022—include Germany, the Netherlands, Denmark, Jay Weiland, a leading COVID modeler, told Fortune.

Will the variant trackers assign JN.1 a new “street name” like Pirola or Kraken?

The group has had “many discussion” as to whether it should give JN.1 its own nickname, Gregory said. On the one hand, only one major mutation separates it from its parent, BA.2.86 “Pirola.” On the other hand, it’s taking off in a way Pirola never did. 

For now, the group has decided not to assign a new name to JN.1, and to reference it as a member of the Pirola family.

“What matters is not individual variants and whether they are going to cause a wave as big as the first Omicron. It’s the idea of evolving lineages,” he said. “It’s consistent with what we said initially: It’s not the variant [BA.2.86], per se, that’s going to be an issue,” but likely what will evolve from it—a whole new line of COVID variants, potentially, in the way Omicron expanded into a family of diverse-yet-similar variants that became increasingly adept at evading immunity and infecting hosts.