A fast-spreading new COVID variant, NB.1.8.1, has now been detected in the U.S

New COVID Variant NB.1.8.1 Detected in the U.S.—Could It Trigger a Summer Surge? With COVID cases expected to rise in the coming months, here's what to know about symptoms, transmission, and how to stay safe

A new, fast-moving COVID variant known as NB.1.8.1. has been detected in the U.S.

koto_feja / Getty Images

  • A new COVID variant, NB.1.8.1, has been detected in the U.S.
  • The variant has been classified as a "variant under monitoring" by WHO, and has been found in 22 countries.
  • Experts say NB.1.8.1 could play a role in a potential COVID summer surge, but symptoms are similar to other COVID infections.

A fast-spreading new COVID variant known as NB.1.8.1 has been detected in the U.S.

Experts say it's too soon to say whether the virus might cause higher COVID cases this summer, but the variant's growth in other parts of the world is prompting close monitoring by health officials. The World Health Organization (WHO) has classified NB.1.8.1 as a "variant under monitoring."

Here's what to know about NB.1.8.1, including where it's spreading, how it compares to previous variants, and whether your current COVID vaccine still offers protection.

Variant  Detected Transmissibility Symptoms Current Spread
 NB.1.8.1 Jan. 2025 Possibly higher Similar to other COVID variants 22 countries

What Is NB.1.8.1?

First detected in late January, NB.1.8.1 is a descendant of the Omicron JN.1 lineage, and has seen a sharp rise in global cases in recent weeks.

According to the most recent data from the WHO, NB.1.8.1. accounted for 10.7% of global sequenced COVID cases between April 21 and April 27—up from 2.5% just a month earlier.

The variant is genetically different from the current dominant strain in the U.S., LP.8.1, said Shira Doron, MD, chief infection control officer at Tufts Medicine.

That difference could be important, as JN.1.8.1 isn't part of the “subvariant soup” that we’ve been seeing in the U.S. in the last couple years, Doron told Health.

Still, the new Omicron variants seem to be evolving to be more similar to one another, she said, which could reduce the risk of a major shift in the disease.

Where Has NB.1.8.1 Been Found?

Fewer than 20 sequences of NB.1.8.1 have been identified in the U.S. so far, according to a spokesperson for the Centers for Disease Control and Prevention (CDC), but the variant has been detected in international travelers at airports in California, Washington, Virginia, and New York City.

Globally, the variant has been spreading rapidly in China and Hong Kong. As of May 28, NB.1.8.1 has been found in 22 countries.

What Are the Symptoms of NB.1.8.1?

Experts agree: the symptoms of NB.1.8.1 look like other COVID infections.

“COVID is COVID is COVID,” William Schaffner, MD, professor of infectious diseases and of health policy at the Vanderbilt University Medical Center, told Health.

“There's never been anything really distinctive about any of these variants," Schaffner added, "except that the earlier COVID variants were more likely to put you in the hospital.”

Most people with NB.1.8.1 can expect to experience symptoms including:

  • Fever or chills
  • Cough 
  • Sore throat 
  • Congestion
  • Fatigue 
  • Difficulty breathing 
  • Diarrhea 

The good news: NB.1.8.1 doesn't appear to cause more severe illness than previous variants.

Could NB.1.8.1 Cause a Summer COVID Surge?

Although NB.1.8.1 only makes up a small percentage of U.S. cases right now, experts are keeping a close eye on it.

The variant carries six spike protein mutations, which could make it more better at spreading and evading antibodies.

Those mutations and preliminary data suggest that NB.1.8.1 may be slightly more transmissible, according to Amy Edwards, MD, infectious disease specialist and associate professor of pediatrics at the Case Western Reserve University School of Medicine.

Still, it's likely that the U.S. could see rising COVID numbers this summer—due to NB.1.8.1 or another variant.

“Unlike influenza, which has one major increase a year in the winter, COVID, over the past several years, has had two: one in the mid-to-late summer, and then again, one in the winter,” Schaffner said.

Also noteworthy: While NB.1.8.1 has multiple mutations, those alone "wouldn't be enough to cause a big surge," said Doron.

Do Current Vaccines Still Work Against NB.1.8.1?

Experts said existing immunity from vaccines or prior infections should provide some protection against NB.1.8.1.

New COVID booster shots from Pfizer, Moderna, and Novavax are also in the works—slated to be available in early fall—and early data suggests they'll work well against NB.1.8.1 or other more common U.S. strains, Doron explained.

A caveat: We don’t actually know which type of vaccine the FDA is going to recommend, Edwards added. So right now, it’s “hard to say” whether a COVID vaccine would be completely effective against NB.1.8.1, she said.

How to Stay Safe as COVID Cases Rise

While NB.1.8.1 isn't causing alarm among experts, many agree that precautions still matter—especially for older adults, immunocompromised individuals, or people with underlying health conditions.

“COVID hasn't disappeared," said Schaffner. "It's still causing about 300 deaths across the country each week. So it's still a notable infection, and it is affecting people in higher risk groups."

Even with booster access up in the air, Doron said she doesn't expect NB.1.8.1 will have a big impact on the trajectory of COVID.

Still, to reduce your risk, Edwards said the following steps can help:

  • Wash your hands regularly
  • Wear a mask and stay home when you're feeling sick
  • Practice proper coughing and sneezing etiquette (into your elbow)

Schaffner summed it up: “We're going to have to keep living with COVID—it's not going away.”

Edited by Amber Brenza Amber Brenza Amber is the Associate Editorial Director overseeing news content for Health, ensuring that readers stay up-to-date on trending topics like COVID-19, as well as the most recent research in the health and wellness space. learn more Read more:

This story originally appeared on: Health News - Author:Julia Landwehr