New COVID Variant NB.1.8.1 'Nimbus' Dominates U.S. Cases Symptoms, Spread, and Vaccine Update

Dominant U.S. Strain

As of late June, NB.1.8.1 accounts for approximately 43% of COVID-19 cases in the United States, making it the most common circulating variant.

Variant Origin

NB.1.8.1 is a subvariant of LP.8.1, which was dominant earlier in the year. It was first identified in China in January 2025 and has since spread to over 22 countries.

Transmissibility

– Virologists consider NB.1.8.1 to be more contagious than previous strains, though there is no current evidence that it causes more severe illness. –

Nickname “Nimbus”

The variant has been informally dubbed “Nimbus” due to its rapid spread and slightly altered genetic makeup

Symptoms

Common symptoms include a severe sore throat (often described as “razor-blade throat”), mild cough, fever, muscle aches, and nasal congestion—similar to earlier variants.

Vaccine Effectiveness

Updated COVID-19 vaccines are still considered effective at preventing severe disease and complications from the new variant.

Presence in Illinois

NB.1.8.1 has been detected in Illinois and at least 17 other U.S. states, including major population centers like California, New Jersey, and New York.

More stories for more update 

Stay connected to us!