A new COVID-19 variant, known as NB.1.8.1 or the “Nimbus variant,” has been making headlines this summer, as it’s currently spreading across several countries, including the United States.
While Nimbus shares many symptoms with previous COVID variants, it stands out for one distinct sign: a sharp, “stabbing sore throat” that affects some people, especially when swallowing.
The World Health Organization and the CDC are closely monitoring the Nimbus variant along with other variants, but as of now, there’s no evidence that Nimbus causes more severe symptoms for most people than previous COVID strains.
What Is the Nimbus COVID Variant?
NB.1.8.1, nicknamed “Nimbus,” is a subvariant of Omicron (JN.1-lineage). The virus has been found to have mutations that help it bind more easily to human cells. This makes it highly transmissible, meaning it spreads faster than some of the earlier COVID-19 variants.
Nimbus was first detected in China in early 2025 and has since been reported in multiple countries, including a growing number of cases across the U.S and Europe.
Common Symptoms of Nimbus
Symptoms of the Nimbus variant have been reported to be mostly mild and typically resemble other respiratory illnesses. That said, some people report intense sore throats from Nimbus, sometimes even described as “sharp” or “stabbing,” especially in the early stages of infection.
The most common COVID Nimbus symptoms include:
- Severe sore throat (often felt while swallowing)
- Persistent fatigue
- Mild cough
- Nasal congestion or a runny nose
- Fever and muscle aches
- Sneezing
- Digestive symptoms like nausea or diarrhea (less common, but possible)
Why the Nimbus Variant Spreads So Easily
NB.1.8.1 is very good at sticking to and getting inside our cells. It attaches strongly to a special part of our cells called the ACE2 receptor, the same spot all COVID-19 variants use to enter.
In lab tests, Nimbus has been shown to infect cells very efficiently, up to 2.5 times more than the previous leading variant. This helps explain why it’s spreading so fast. It’s not necessarily better at sneaking past people’s immune systems or more dangerous, but it gets into cells more easily.
Still, Nimbus doesn’t seem to make the average person any sicker than other variants, and experts say there is currently no reason to worry about increased hospitalizations or deaths.
What About the Stratus Variant?
Another COVID variant, called Stratus (XFG), isn’t as good at getting into cells, but it dodges immune defenses better. It has mutations that help it escape antibodies, which are the proteins your body makes to fight off infections.
That means it might spread easily by avoiding detection, but it’s not as naturally infectious as Nimbus or likely to cause severe symptoms.
Who Is Most at Risk for Nimbus?
Like earlier COVID-19 strains, the Nimbus variant poses a higher risk to:
- Older adults
- People with chronic health conditions like heart disease, diabetes or lung disorders
- Immunocompromised individuals
- Anyone who is unvaccinated
Children and healthy adults can still become infected, but are less likely to experience severe symptoms from the infection.
While most people recover from COVID at home, those with underlying conditions should take extra care. COVID can still lead to complications or long-term symptoms known as long COVID.
How to Protect Yourself from COVID This Fall
With more indoor gatherings as the weather gets cooler, COVID spikes are expected. Fortunately, the same basic precautions still apply as in previous years and remain effective against different COVID variants.
It is, however, important to recognize that getting one variant of COVID won’t protect you against getting a different variant.
Are COVID Vaccines Helpful Against Nimbus?
Yes. Even though both Nimbus and Stratus make it a little harder for your body’s antibodies to work, the vaccines still offer good protection. They’re especially helpful for fighting serious illness, hospital stays and death.
Getting “boosted” every year is recommended to help keep your immune system prepared for these newer variants.
Steps to Reduce Your Risk:
- Get vaccinated: Current COVID vaccines from Moderna, Pfizer-BioNTech and Novavax remain effective against the JN.1 lineages of the Omicron variants NB.1.8.1. They help protect against severe illness and hospitalization, even with newer strains.
- Practice good hygiene: Wash your hands often, cover your mouth and nose when sneezing or coughing, and avoid touching your face.
- Consider wearing a mask in crowded spaces: Keep a mask handy when flying, using public transit or in poorly ventilated indoor areas.
- Stay home if you’re sick: Even mild symptoms like a sore throat or stuffy nose could indicate COVID. Protect others by resting and isolating if needed.
- Improve airflow in your home: Open windows or spend time outdoors whenever possible. Fresh air reduces the risk of airborne transmission.
How Is Nimbus Treated?
For most people, symptoms of the Nimbus variant can be managed with rest, fluids, over-the-counter pain relievers (such as Tylenol or Advil), and isolation to prevent others from getting sick.
If you or someone in your household has COVID, especially if they have underlying health issues, speak with your healthcare provider about antiviral options like Paxlovid.
Call 911 or seek emergency care if you experience:
- Difficulty breathing
- Chest pain or pressure
- Confusion or trouble staying awake
- Pale, gray or blue-colored lips or skin
COVID-19 isn’t going away, but we’ve come a long way in learning how to live with it. Knowing the symptoms of new variants like Nimbus, staying current with your vaccines, and taking simple preventive measures can help you avoid infection or reduce its severity.
