New COVID-19 Variant NB.1.8.1 Detected in California: What You Need to Know
A new COVID-19 variant, designated NB.1.8.1, has been identified in California and several other U.S. states, raising concerns among health officials due to its increased transmissibility. First detected in China earlier this year, the variant has since been found in travelers arriving at U.S. airports, including those in California, Washington, Virginia, and New York.
FEATUREDHEALTH
Discovery and Spread
The NB.1.8.1 variant was initially identified in January 2025, with the first U.S. case confirmed by Stanford University's Clinical Virology Laboratory on April 17 . Subsequent detections have occurred through the Centers for Disease Control and Prevention's (CDC) airport screening program, which monitors international travelers for emerging variants.
Wastewater surveillance has also indicated the presence of NB.1.8.1 in California communities, suggesting that the variant is circulating within the state .
Characteristics and Symptoms
NB.1.8.1 is a subvariant of the Omicron lineage, known for its high transmissibility. Preliminary studies suggest that NB.1.8.1 may bind more effectively to human cells, potentially increasing its infectiousness.
Common symptoms associated with NB.1.8.1 are similar to those of other COVID-19 variants and include:
Sore throat
Fever
Fatigue
Cough
Congestion
Despite its increased transmissibility, there is currently no evidence to suggest that NB.1.8.1 causes more severe illness compared to previous variants.
Public Health Response
The World Health Organization (WHO) has classified NB.1.8.1 as a "variant under monitoring," indicating that it is being closely observed for potential changes in transmissibility, severity, or impact on public health measures.
In the United States, health officials are emphasizing the importance of continued vigilance, including vaccination, masking in crowded indoor settings, and staying home when symptomatic. However, recent policy changes have altered vaccine recommendations. As of May 2025, COVID-19 vaccines are no longer recommended for healthy children and pregnant women, a decision that has sparked debate among public health experts.
Looking Ahead
While the emergence of NB.1.8.1 has prompted increased surveillance and monitoring, experts caution against panic. Dr. John Swartzberg, an infectious disease specialist at UC Berkeley, notes that while the variant appears more transmissible, it does not seem to cause more severe illness. He advises continued adherence to public health guidelines and staying informed about new developments.
As the situation evolves, health authorities will continue to assess the impact of NB.1.8.1 and adjust recommendations accordingly to protect public health.
For more information on COVID-19 variants and public health guidelines, visit the CDC and WHO websites.