A newly identified COVID-19 variant, NB.1.8.1—also called “Nimbus”—is rapidly gaining ground worldwide and in the United States. According to recent data from the U.S. Centers for Disease Control and Prevention (CDC), Nimbus accounted for an estimated 37% of U.S. cases in the two weeks ending June 7.
“Nimbus spreads faster than previous variants,” says Dr. Magdalena Sobieszczyk, chief of the Division of Infectious Diseases at NewYork-Presbyterian/Columbia University Irving Medical Center. “Its mutations help it bind more efficiently to human cells, giving it a clear advantage in transmission.”
Despite its rapid spread, you can still take effective steps to reduce your risk. Simple preventive measures—such as staying up to date with COVID vaccines, washing your hands frequently, and wearing a mask in crowded indoor spaces—remain important, especially during summer travel.
“Summer may bring a rise in COVID cases due to increased travel,” notes Dr. Sobieszczyk. “However, more time spent outdoors, where ventilation is better, could help balance that risk.”
Health Matters spoke with Dr. Sobieszczyk to break down what to know about the NB.1.8.1 variant, the latest guidance on vaccines, and practical ways to protect yourself and others this summer.
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Is the new COVID variant Nimbus more transmissible?
NB.1.8.1 has triggered a noticeable surge in COVID-19 infections, emergency room visits, and hospitalizations across several countries—most significantly in China, where the variant was first identified. Experts believe that specific genetic mutations may be driving its increased transmissibility compared to earlier variants.
In the United States, NB.1.8.1 began appearing earlier this year and has since gained momentum. With cases steadily rising, the CDC has officially included the variant in its COVID Data Tracker for ongoing monitoring.
What are the symptoms of Nimbus? Are they similar or different from other COVID variants?
NB.1.8.1 appears to cause more allergy-like symptoms, including sneezing and a runny or stuffy nose. However, overall symptoms remain similar to those seen with other COVID-19 variants. Common signs of infection include sore throat, nasal congestion, mild cough, fever, and fatigue. The good news is that, so far, NB.1.8.1 has not been linked to more severe illness compared to previous variants.
Which COVID vaccines are currently available?
The COVID-19 vaccines from Moderna, Pfizer-BioNTech, and Novavax are all approved by the U.S. Food and Drug Administration (FDA) for use. These vaccines are expected to provide strong protection against severe illness, including from the NB.1.8.1 variant. That’s because NB.1.8.1—and most other circulating variants—are part of the Omicron JN.1 lineage, which the current vaccines are specifically designed to target.
Who can receive the shots?
COVID-19 vaccines remain part of the CDC’s recommended immunization schedule for all age groups—including infants, children, adolescents, and adults. This includes individuals who are moderately or severely immunocompromised, regardless of whether they’ve been previously vaccinated.
The CDC recently updated its guidance for children ages 6 months to 17 years. It now recommends that parents, guardians, and caregivers consult with a healthcare provider to understand the benefits of COVID vaccination and make informed decisions based on individual health needs.
With a potential surge in COVID cases this summer, do you consider the virus seasonal or year-round?
The emergence of new COVID-19 variants during the summer challenges the idea that COVID is strictly a cold-weather virus. “COVID-19 is proving to be a year-round illness, not just a seasonal winter infection,” says Dr. Sobieszczyk. While viruses like the flu typically peak in the colder months, they can also extend into spring—much like what we’re now seeing with COVID.
What are additional ways people can protect themselves from COVID, especially during the summer travel season?
Respiratory illnesses like COVID-19, RSV, and the flu can have lingering effects on your health. In particular, COVID-19 may lead to long-term symptoms—commonly known as long COVID—in some individuals. “It’s essential to talk with your healthcare provider about personalized strategies to stay protected, especially if you or your loved ones have underlying conditions such as diabetes, heart disease, or high blood pressure,” advises Dr. Magdalena Sobieszczyk.
Alongside vaccination, a few key preventive steps remain crucial as summer travel and gatherings ramp up:
- Cover your mouth and nose when coughing or sneezing—preferably with a tissue.
- Wash and sanitize your hands frequently.
- Choose well-ventilated spaces whenever possible.
- Stay home if you’re feeling unwell.
- Keep a mask handy, especially when flying or in crowded indoor settings.
About Dr. Magdalena Sobieszczyk
Dr. Sobieszczyk serves as Chief of the Division of Infectious Diseases at NewYork-Presbyterian/Columbia University Irving Medical Center and is the Harold Neu Professor of Infectious Diseases in Medicine at Columbia University Vagelos College of Physicians and Surgeons. A leading clinical virologist, she is also the principal investigator of the Columbia Collaborative Clinical Trials Unit, funded by the NIH, and is advancing research into infectious diseases such as SARS-CoV-2 and HIV.
Frequently Asked Questions
What is the NB.1.8.1 (Nimbus) COVID variant?
NB.1.8.1, also known as Nimbus, is a new subvariant of Omicron that has rapidly spread in several countries, including the U.S. It carries genetic mutations that may make it more transmissible than earlier variants.
Where was the NB.1.8.1 variant first detected?
This variant was first identified in China, where it contributed to a surge in COVID-related infections, hospitalizations, and emergency room visits.
How widespread is NB.1.8.1 in the United States?
According to the CDC, NB.1.8.1 accounted for approximately 37% of U.S. COVID cases during the two-week period ending June 7. It continues to rise in prevalence.
Is NB.1.8.1 more dangerous than previous variants?
So far, there is no evidence that NB.1.8.1 causes more severe illness. However, its higher transmissibility means it may lead to more infections, especially in crowded or poorly ventilated areas.
Do current vaccines protect against NB.1.8.1?
Yes. The latest COVID-19 vaccines from Moderna, Pfizer-BioNTech, and Novavax are designed to target Omicron subvariants, including NB.1.8.1, and provide strong protection against severe illness.
Who should get vaccinated or boosted?
The CDC recommends COVID-19 vaccination for everyone aged 6 months and older. This includes people with underlying health conditions or weakened immune systems. Talk to your healthcare provider for personalized guidance.
Can you get COVID in the summer?
Absolutely. COVID-19 is now considered a year-round illness, not just a winter virus. Travel, indoor gatherings, and low ventilation in summer can contribute to its spread.
Conclusion
The rise of the NB.1.8.1 (Nimbus) COVID variant is a reminder that the virus continues to evolve—and so must our awareness and precautions. While this variant appears more transmissible, current vaccines still offer strong protection against severe illness. By staying informed, practicing good hygiene, keeping up with vaccinations, and making smart choices in crowded or indoor settings, you can significantly lower your risk this summer.
COVID-19 may no longer dominate headlines, but it remains a year-round health concern. With the right tools and guidance, you can enjoy the season while staying safe and protecting those around you.