A new COVID-19 variant, officially designated NB.1.8.1 and nicknamed "Nimbus," is rapidly spreading across the United States and parts of the world, causing an unusual and painful symptom that has caught public attention: a sore throat described by many as feeling like swallowing razor blades or broken glass. This intensely painful "razor blade throat" symptom, while alarming, is part of a constellation of typical COVID-19 symptoms and has prompted health experts to issue guidance on how to protect oneself and manage the illness.
First detected in China in January 2025, NB.1.8.1 is a descendant of the Omicron variant and a recombinant variant known as XVD.1.5.1. It has since spread internationally, with cases reported in Asia, Europe, and North America. According to the World Health Organization (WHO), this variant has been designated a "variant under monitoring," signaling the need for close observation without raising immediate alarm. The WHO’s May 2025 report evaluated the additional public health risk posed by NB.1.8.1 as low at the global level, underscoring that currently approved COVID-19 vaccines remain effective against symptomatic and severe disease caused by this variant.
In the United States, data from the Centers for Disease Control and Prevention (CDC) shows that NB.1.8.1 accounts for approximately 37% of COVID-19 cases as of early June 2025, making it the second most dominant strain behind LP.8.1, which holds 38% of cases. This rapid rise has led experts to predict that Nimbus could become the predominant strain in the country by the end of June.
The variant’s increased transmissibility is attributed to several mutations in the spike protein, which allow the virus to attach more easily to ACE2 receptors on human cells. Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco, explained that these changes may help the virus spread more efficiently, though so far, NB.1.8.1 has not caused a surge in hospitalizations or deaths, with rates remaining stable.
Patients infected with Nimbus often report the hallmark "razor blade throat," a sore throat so painful that it feels like shards of glass cutting the throat. Pulmonologist Dr. Ahmed Salem of Sharp Memorial Hospital in San Diego described the sensation vividly, saying, "It's not just [a] sore throat. I mean, people are saying it feels like glass is cutting them." Despite this discomfort, Salem reassured that the variant appears less virulent than previous strains, with no observed increase in mortality.
Other typical COVID-19 symptoms persist with this variant, including fever, chills, cough, shortness of breath, congestion, runny nose, loss of taste or smell, fatigue, muscle aches, headaches, nausea, vomiting, and diarrhea. The severe sore throat usually lasts about a week, and standard remedies such as salt water gargles, lozenges, lidocaine sprays, rest, and hydration are recommended for symptom relief.
While the painful throat symptom has gained attention, some experts emphasize that sore throat has long been a common symptom of COVID-19, reported by about 70% of patients. Yale School of Medicine’s Assistant Professor Scott Roberts noted that the "razor blade throat" is anecdotal and there is no definitive evidence that NB.1.8.1 causes more severe throat pain than other variants. However, he advised that anyone experiencing severe throat pain should get tested for COVID-19 and consult a healthcare provider to rule out bacterial infections like strep throat, which require antibiotic treatment to prevent serious complications.
In light of the variant’s spread, public health officials continue to stress the importance of vaccination. The CDC recommends that everyone over six months old receive the 2024-2025 COVID-19 vaccine, particularly emphasizing older adults, immunocompromised individuals, pregnant people, and those living in long-term care facilities. Subhash Verma, a microbiology professor at the University of Nevada, Reno, described NB.1.8.1 as a "slightly upgraded version" of LP.8.1 that can evade antibodies from vaccines or past infections more easily, making vaccination and updated boosters crucial.
However, recent policy changes have introduced some uncertainty. Health and Human Services Secretary Robert F. Kennedy Jr. recommended removing the COVID-19 vaccine from the CDC’s immunization schedule for healthy children and pregnant women. Additionally, the Food and Drug Administration (FDA) announced plans to require new clinical trials for annual COVID-19 boosters for healthy individuals under age 65, potentially leading to out-of-pocket costs for some who wish to receive the vaccine.
Testing remains a key tool in managing the pandemic. The federal Increasing Community Access to Testing, Treatment and Response (ICATT) program continues to offer free COVID-19 testing at over 19,000 locations nationwide. Experts advise that individuals who test positive isolate until fever-free for 24 hours and then continue masking and taking precautions for five additional days. Those exposed to COVID-19 should test on days one, three, and five post-exposure while monitoring symptoms and wearing masks.
Despite the rise of the Nimbus variant and its painful throat symptom, hospitalizations and severe cases remain relatively low. Texas Health and Human Services data shows a decline in COVID-19-related emergency room visits and deaths in June 2025, following a peak in winter. Wastewater testing in the U.S. region also has not indicated a significant rise in COVID-19 cases as of May 2025, contrasting with global trends where the variant is more prevalent, especially in the Eastern Mediterranean, Southeast Asia, and Western Pacific regions.
Experts continue to urge the public to maintain basic preventive measures such as frequent handwashing, good hygiene, mask-wearing in crowded or high-risk settings, and ensuring proper ventilation indoors. These strategies, combined with vaccination and testing, remain the best defense against COVID-19 and its evolving variants.
While the "razor blade throat" symptom has caused understandable concern, the overall picture remains cautiously optimistic. The Nimbus variant, though more transmissible and marked by a distinctive sore throat, has not led to increased hospitalizations or deaths. As Dr. William Schaffner from Vanderbilt University Medical Center noted, "There is currently no evidence that NB.1.8.1 causes more severe disease or is more likely to cause hospitalization." Still, vigilance is warranted, especially for high-risk groups, as the virus continues to mutate and circulate.
So, if you find yourself battling a sore throat that feels sharper than usual, don’t ignore it. Get tested, stay hydrated, rest up, and follow public health guidance. And remember, the pandemic is far from over, but with knowledge, caution, and science on our side, we can navigate these new challenges together.
