Nimbus COVID Variant in the US: What to Know About the New Strain Surging from China

Nimbus COVID Variant: What to Know as It Spreads in the U.S.

A new coronavirus strain, officially known as NB.1.8.1 and commonly referred to as the Nimbus COVID Variant, is rapidly gaining ground in the United States. Although its rise is notable, experts agree it has yet to show increased severity compared to previous strains.

What Is the Nimbus COVID Variant?

The Nimbus COVID Variant traces its roots back to the Omicron lineage and was first identified in January 2025. By mid-May, it made up about 11% of global cases—and by early June, the variant accounted for roughly 37% of COVID cases in the U.S. and has been detected in at least 14 states healthline.com+13ctinsider.com+13sfgate.com+13healthmatters.nyp.org+1reddit.com+1. The World Health Organization classifies Nimbus as a “variant under monitoring,” indicating careful observation without immediate global health concern katiecouric.com+10gavi.org+10indianexpress.com+10.

Contagiousness of the Nimbus COVID Variant

Nimbus exhibits several mutations in its spike protein that appear to boost transmissibility m.economictimes.com+7sfgate.com+7wired.com+7. It binds more efficiently to ACE2 receptors in human cells—an attribute typical of more infectious variants yahoo.com+15gavi.org+15healthmatters.nyp.org+15. This mutation may help explain why it spread so quickly and now comprises over a third of U.S. cases aol.com+15healthmatters.nyp.org+15katiecouric.com+15. Scientists describe Nimbus as likely out-competing older Omicron subvariants due to its enhanced transmissibility, although it does not appear to be more virulent ctinsider.com+12houstonchronicle.com+12healthline.com+12.

Symptoms: What Sets Nimbus COVID Variant Apart

One hallmark symptom of the Nimbus COVID Variant is an intense sore throat, famously dubbed “razor blade throat” gavi.org+15apnews.com+15reddit.com+15. Patients describe it as feeling like swallowing shards of glass or razor blades. However, experts caution this symptom is anecdotal and still falls within the broader COVID symptom spectrum m.economictimes.com. Other common symptoms—such as fever, fatigue, nasal congestion, mild cough, muscle aches, and gastrointestinal upset—remain consistent with other Omicron variants healthmatters.nyp.org.

Is the Nimbus COVID Variant More Dangerous?

So far, there’s no compelling evidence to suggest that the Nimbus COVID Variant causes more severe illness, hospitalizations, or deaths than earlier variants . Hospitalization rates remain steady, and while test positivity has edged upward in states like California, it is early in the trend sfgate.com. Officials continue to monitor the data to confirm whether Nimbus leads to more hospital admissions or intensive care cases.

Vaccine and Treatment Implications for Nimbus COVID Variant

Current evidence suggests that existing COVID vaccines should still offer strong protection—particularly against severe disease—even with the Nimbus COVID Variant in circulation healthmatters.nyp.org. Laboratory data indicates only a modest drop in antibody neutralization—roughly 1.6-fold—which should still shield against hospitalization and death indianexpress.com+7gavi.org+7houstonchronicle.com+7. The WHO emphasizes that vaccines remain effective and continues to monitor new formulations for potential updates against emerging variants reddit.com+9gavi.org+9wired.com+9.

Where Nimbus COVID Variant Has Been Detected

The Nimbus COVID Variant has been reported in multiple U.S. states, including California, New York, Texas, Illinois, Connecticut, and Washington medicalxpress.com+15ctinsider.com+15reddit.com+15. It also figures prominently in wastewater surveillance and airport screening efforts gavi.org+3livemint.com+3m.economictimes.com+3. Its prevalence mirrors a regular summer pattern, hinting at a potential seasonal wave of COVID sfgate.com.

Protecting Yourself Against the Nimbus COVID Variant

Public health officials recommend taking sensible steps to lower your risk from the Nimbus COVID Variant:

• Stay up-to-date with vaccinations, especially for high-risk groups—seniors, those with chronic illness, and immunocompromised individuals sfgate.com.
• Practice good hygiene: regular hand-washing, mask-wearing in crowded or indoor settings, especially for vulnerable populations .
• Boost ventilation in indoor spaces and test promptly if symptoms arise .
• Avoid large gatherings if you’re at high risk, and follow local health guidance.
• Consider masks on public transport or planes, especially with increased summer travel.

Doctors also advise staying alert to that hallmark sore throat—especially if you experience it with other COVID symptoms—and testing early .

Outlook on the Nimbus COVID Variant

The trajectory of the Nimbus COVID Variant fits established COVID waves: a surge, plateau, and eventual decline . Although vaccines and improved immunity may blunt its impact, the variant’s transmissibility suggests we should brace for a summer wave.

For most people, Nimbus may not mean severe illness—but it can still be disruptive. Staying informed, boosted, and cautious in high-risk scenarios remains vital to protecting both personal health and community well-being.

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