WASHINGTON, D.C. – A new COVID-19 variant, designated NB.1.8.1, has been detected in the United States and is currently classified as a “variant under monitoring” by the World Health Organization (WHO). First identified in late January 2025, NB.1.8.1 is a descendant of the Omicron JN.1 lineage and has been found in 22 countries globally.
Experts are closely monitoring NB.1.8.1 as its growth in other parts of the world suggests it could contribute to a potential summer surge in COVID-19 cases. Between April 21 and April 27, NB.1.8.1 accounted for 10.7% of global sequenced COVID cases, a significant increase from 2.5% just a month prior.
While fewer than 20 sequences of NB.1.8.1 have been identified in the U.S. so far, it has been detected in international travelers at airports in California, Washington, Virginia, and New York City. The variant has been spreading rapidly in China and Hong Kong.
Symptoms and Severity: Symptoms associated with NB.1.8.1 are similar to other COVID-19 infections, including fever or chills, cough, sore throat, congestion, fatigue, difficulty breathing, and diarrhea. Experts emphasize that “COVID is COVID is COVID,” noting that there hasn’t been anything truly distinctive about the symptoms of various COVID variants. The good news is that NB.1.8.1 does not appear to cause more severe illness than previous variants.
Transmissibility and Summer Outlook: The variant carries six spike protein mutations, which could potentially enhance its ability to spread and evade antibodies. Preliminary data suggests NB.1.8.1 may be slightly more transmissible. While it currently accounts for a small percentage of U.S. cases, the country has historically experienced COVID-19 surges in mid-to-late summer, in addition to winter peaks.
Vaccine Protection: Experts believe that existing immunity from vaccines or prior infections should offer some protection against NB.1.8.1. New COVID booster shots from Pfizer, Moderna, and Novavax are anticipated to be available in early fall, with early data suggesting they will be effective against NB.1.8.1 and other common U.S. strains.
Staying Safe: Though NB.1.8.1 is not causing alarm among experts, precautions remain important, particularly for older adults, immunocompromised individuals, and those with underlying health conditions. COVID-19 continues to be a notable infection, still causing approximately 300 deaths per week across the country.
To reduce risk, individuals are advised to:
- Wash hands regularly
- Wear a mask and stay home when feeling sick
- Practice proper coughing and sneezing etiquette (into your elbow)
Experts reiterate that “We’re going to have to keep living with COVID—it’s not going away.”
