A new COVID-19 subvariant, officially known as NB.1.8.1 but widely nicknamed “Nimbus,” is currently circulating, and reports link it to a particularly severe symptom: an excruciating sore throat. Described by some individuals as feeling like swallowing “razor blades” or even shards of glass, this intense throat pain has brought the Nimbus variant into the spotlight.
While a sore throat has long been a recognized symptom of COVID-19, the “razor blade throat” description highlights the reported intensity of pain associated with this specific variant by some patients and healthcare providers in various countries, including the U.S., UK, and India. It’s a colloquial term used to convey the sensation of having a throat covered with sharp objects.
What is the Nimbus Variant (NB.1.8.1)?
Nimbus is classified as a subvariant of the Omicron lineage. First identified in China in January, it has since spread globally, detected in at least 22 countries. Data from late May and early June 2025 showed a rapid increase in its prevalence in the United States, accounting for around one-third (approx. 37%) of new COVID-19 cases, putting it on par with the previously dominant strains. The variant has also seen recent increases globally, particularly in regions like the eastern Mediterranean, Southeast Asia, and the western Pacific.
Scientists believe Nimbus possesses genetic changes that may enhance its ability to spread and potentially evade the immune system compared to earlier variants. This likely contributes to its increased transmissibility.
Beyond the Sore Throat: Other Symptoms
While the severe sore throat is the symptom gaining specific attention, infection with the Nimbus variant presents with symptoms common to other COVID-19 strains. These can include:
Fever and chills
Cough
Fatigue and muscle aches
Congestion or runny nose
Shortness of breath
Loss of taste or smell (though less frequent now than with earlier variants)
Headaches and body aches
Diarrhea, nausea, and vomiting
Less common: skin rash, discoloration of fingers or toes, red/irritated eyes
Expert Insights: How Concerned Should You Be?
Despite the dramatic description of the sore throat and the variant’s increasing spread, experts currently state there is no significant cause for alarm regarding the Nimbus variant overall.
The World Health Organization (WHO) has classified NB.1.8.1 as a “variant under monitoring,” meaning it’s being tracked due to its spread, but it does not currently pose a major global public health risk. Available data does not suggest that illness caused by the Nimbus variant is more severe compared to other circulating SARS-CoV-2 variants. Routine surveillance has not shown an increase in hospitalizations or deaths specifically linked to this variant.
Experts note that the “razor blade throat” description, while painful for those experiencing it, is currently anecdotal. While the symptom might feel unusually intense for some, there is no current evidence to prove it is objectively more severe or unique than sore throats caused by previous COVID-19 variants. Sore throat has long been a symptom of COVID-19.
Furthermore, current COVID-19 vaccines are expected to maintain effectiveness against the Nimbus variant, particularly in preventing severe illness, hospitalization, and death.
COVID Sore Throat vs. Strep Throat
Experiencing a severe sore throat can be alarming, and it’s crucial to differentiate between a viral infection like COVID-19 (including the Nimbus variant) and a bacterial infection like strep throat.
COVID-19: Causes sore throat due to the virus directly infecting cells in the throat, leading to inflammation. Other common COVID symptoms are usually present (cough, fever, fatigue, etc.).
Strep Throat: Caused by group A Streptococcus bacteria. Often characterized by a sudden, severe sore throat, fever, white patches on the tonsils, headache, chills, and swollen lymph nodes. Unlike viral infections, strep throat requires antibiotic treatment to prevent serious complications like rheumatic fever or kidney problems.
Because symptoms can overlap, experts recommend getting tested for both COVID-19 and strep throat if you experience a severe sore throat, especially if strep-like symptoms are present.
Protecting Yourself and Others
Protection measures against the Nimbus variant remain consistent with those for previous COVID-19 strains and other respiratory viruses:
Hand Hygiene: Wash hands frequently with soap and water or use hand sanitizer.
Avoid Sick Individuals: Maintain distance from people who are ill.
Ventilation: Improve airflow in indoor spaces.
Masking: Consider wearing masks in crowded indoor settings or high-risk situations.
Testing: Get tested if you develop symptoms to confirm the cause and prevent further spread.
Vaccination Updates
Staying up-to-date with COVID-19 vaccination is still recommended, particularly for older adults, individuals with underlying health conditions, and those previously unvaccinated, to maintain protection against severe outcomes. While immunity from previous infection or vaccination can wane, updated vaccines continue to be an important layer of defense.
It’s worth noting that official COVID-19 vaccine recommendations have been evolving. Recent updates from health authorities have refined eligibility for potential fall vaccinations, prioritizing groups like adults aged 65 and older and younger individuals with specific health conditions, in contrast to earlier broader recommendations. It’s important to follow the latest guidance from health officials regarding vaccine eligibility.
When to Seek Medical Attention
While most COVID-19 cases with the Nimbus variant are not expected to be more severe overall, certain “red flag” symptoms warrant consulting a physician:
Severe throat pain that makes swallowing extremely difficult
Sore throat lasting longer than a week
Unexplained weight loss
Feeling like food is sticking in your throat
New or worsened shortness of breath
Symptoms of strep throat (high fever, white patches on tonsils)
In summary, the Nimbus variant is a circulating Omicron subvariant gaining attention partly due to reports of intensely painful “razor blade” sore throats. While it shows increased transmissibility, experts currently assess its overall public health risk as low and do not believe it causes more severe illness than other variants. Standard precautions and vaccination remain key protective measures, and testing is important for diagnosis, especially when distinguishing from conditions like strep throat.
