New COVID Variant NB.1.8.1 Spreads in the U.S., Foreshadowing a Likely Summer Surge

A new COVID variant known as NB.1.8.1 is on the rise in the U.S. and beyond, landing on the radar of health officials. The variant, first identified in January 2025, is now being closely monitored, with cases already popping up across several states. 

A report released by the World Health Organization (WHO) Technical Advisory Group states that the global public health risk posed by NB.1.8.1 is currently low; it also says, however, that the variant’s mutations may increase its ability to be transmitted. Learn how you can stay vigilant in case of potential COVID surges this summer. 

What Is the New COVID Variant, NB.1.8.1?

NB.1.8.1 is an Omicron descendant lineage of SARS-CoV-2; having already spread rapidly in Asia, the variant has made its way into the U.S., Europe, and Australia. The WHO report confirms that as of May 18, 2025, NB.1.8.1 has appeared in 22 countries.

Cases in the U.S. have entered through airports, caught during screenings of international travelers in California, Virginia, New York, and Washington State. In early June 2025, 14 detections of the variant were confirmed in Washington State. The variant has also been reported in other states like Ohio, Rhode Island, and Hawaii. 

According to the WHO report, NB.1.8.1 represented 10.7 percent of all COVID sequences submitted to the Global Initiative on Sharing All Influenza Data (GISAID) in epidemiological week 17 (April 21 to 27). This rose from 2.5 percent a month earlier in epidemiological week 14 (March 31 to April 6). 

Read More: A Bat Virus Could Someday Spill Over to Humans, Tipping Off a New Pandemic

Symptoms of NB.1.8.1

Health officials have suggested that the effects of NB.1.8.1 won’t be any more severe than other variants. The symptoms include fever, sore throat, congestion, body aches, and fatigue. 

What may set NB.1.8.1 apart is its likelihood of exhibiting increased transmissibility, meaning mutations would allow it to evade antibodies produced by vaccinated or previously infected people. As a result, the variant could be passed on to others more easily, but the WHO is saying that more data is needed to determine the true risk regarding antibody escape.

The WHO report says that “current vaccines are expected to remain effective to this variant against symptomatic and severe disease”. The Centers for Disease Control and Prevention (CDC) recommends a COVID-19 vaccine for most individuals 18 and older, and advises parents of children ages 6 months to 17 years to discuss the benefits of a vaccination with a healthcare provider.

Getting Ready for a Summer Surge

Health officials are now keeping a close eye on NB.1.8.1, classifying it as a variant under monitoring (VUM). Other variants that are currently in this category include KP.3, KP.3.1.1., LB.1, XEC, and LP.8.1. Among these variants, LP.8.1 had begun to gain ground earlier in 2025, but the WHO report says that it is now starting to decline (although it is still the dominant variant in the U.S.)

In addition to the VUMs, there is also one variant of interest (VOI): JN.1, which was first identified in August 2023. This variant has been noted for its high transmissibility, especially in cold, dry climates. While VUMs require more testing to establish their true risks to public health, VOIs are explicitly confirmed to have genetic changes that affect virus characteristics like transmissibility and virulence.

Surges of COVID tend to strike during the summer, and NB.1.8.1 may be a driving force this time around. A potential surge is not yet in full force, though; current CDC data shows that as of June 3, 2025, COVID-19 infections are growing or likely growing in 6 states, but declining or likely declining in 14 states (and not changing in 25 states).

Read More: Evidence of Origins of the COVID-19 Outbreak Disputes the Lab Leak Theory

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• University of Minnasota. WHO adds NB.1.8.1 as SARS-CoV-2 variant under monitoring

• University of Chicago Medicine. What do we know about the new Omicron subvariant of COVID, NB.1.8.1?

• CDC. New COVID Variant NB.1.8.1 Spreads in the U.S.,… — Content — Science — Contentful

• CDC. COVID Data Tracker

• WHO. WHO Coronavirus Network (CoViNet)

• CDC. Current Epidemic Trends

Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.