Covid ‘Razor Throat’ Variant Now Found in Over 15 Us States

Imagine swallowing glass every time you try to speak, eat, or even breathe. That’s how some people are describing the intense throat pain caused by the latest COVID-19 variant spreading across the United States—so sharp and searing it’s been dubbed the “razor blade throat” variant.

Officially named NB.1.8.1 and informally known as “Nimbus,” this new strain has swiftly become the dominant variant in the U.S., accounting for over 40% of cases by late June. First detected in early 2025, it’s now reported in more than 15 states—and likely more, given the decline in genomic sequencing.

While experts caution that the variant doesn’t appear to cause more severe illness overall, the vivid symptoms and rapid spread are raising questions: What makes Nimbus different? Should we be concerned about the return of widespread infections? And how can we protect ourselves and others this summer?

What Is the ‘Razor Throat’ COVID Variant (NB.1.8.1 / Nimbus)?

The COVID-19 variant known as NB.1.8.1—nicknamed “Nimbus”—is the latest sublineage of the Omicron family to gain global attention. First identified in January 2025 in China, it has since spread internationally and is now the dominant strain in the United States, making up an estimated 43% of new cases by late June, according to data from the U.S. Centers for Disease Control and Prevention (CDC).

While its clinical severity appears similar to previous Omicron strains, Nimbus has drawn attention for two main reasons: its rapid rise in prevalence and a particularly painful sore throat symptom some patients describe as feeling like “swallowing razor blades.” Though not exclusive to this variant, the intensity of the throat pain has become a defining and widely discussed feature of recent infections.

From a genetic standpoint, NB.1.8.1 is a descendant of XVD.1.5.1, itself a recombinant variant of Omicron. According to Dr. Peter Chin-Hong, infectious disease expert at the University of California, San Francisco, NB.1.8.1 appears to have mutations in the spike protein that may allow it to more easily attach to ACE2 receptors—proteins on the surface of human cells that the virus uses to gain entry. This could explain its increased transmissibility.

Despite this, there is no current evidence that Nimbus causes more severe illness. The World Health Organization (WHO) has designated it as a “variant under monitoring”, a status that indicates growing global prevalence but no immediate signs of increased virulence or vaccine resistance. Most people infected with Nimbus experience symptoms consistent with previous COVID variants, including congestion, fatigue, fever, and cough—though the razor-like sore throat is being reported more frequently.

What sets Nimbus apart, then, is less about danger and more about its potential to spread quickly and uncomfortably. Experts stress that while it does not appear to pose a greater threat in terms of hospitalization or mortality, the symptoms and swiftness of its spread warrant continued monitoring and responsible public health measures.

What Are The Symptom?

Medically, the sensation stems from inflammation in the oropharynx, the part of the throat just behind the mouth. When a virus like COVID-19 infects these tissues, it can lead to acute pain, swelling, and irritation. “A ‘razor blade throat’ is a very descriptive term describing severe sore throat pain—as if their throat is covered with razor blades,” explains Dr. Aaron Glatt, infectious disease specialist and chair of medicine at Mount Sinai South Nassau in New York.

It’s important to note that while this symptom is strongly associated with the current wave of COVID-19 cases, it’s not exclusive to Nimbus. Similar throat pain can occur with other viral illnesses (like influenza or mononucleosis), bacterial infections (such as strep throat), and even from environmental irritants like smoke or allergens. That said, its frequent appearance in recent cases has made it a defining marker for many experiencing COVID this summer.

Alongside razor blade throat, the full range of symptoms tied to NB.1.8.1 includes:

• Fever or chills
• Fatigue
• Cough (often dry)
• Congestion or runny nose
• Headache
• Muscle and body aches
• Loss of taste or smell (less common than earlier variants)
• Shortness of breath
• Nausea, vomiting, or diarrhea
• Sore throat (often unusually intense)

The CDC reports that sore throat now ranks among the most common early symptoms of COVID, affecting about 70% of infected individuals, and in the case of Nimbus, that symptom is frequently more pronounced.

While “razor blade throat” can sound alarming, it generally resolves within a few days to a week. However, if the symptom persists longer than seven days, or is accompanied by difficulty swallowing, breathing issues, or a high fever, it may warrant medical evaluation to rule out more serious conditions or co-infections.

Where and How the Variant Is Spreading

Since its initial detection in January 2025, the NB.1.8.1 variant—nicknamed Nimbus—has made a steady and now dominant rise across the United States. As of late June, it accounts for approximately 43% of all new COVID-19 cases, according to the CDC’s Nowcast tracker, overtaking previous leading variants such as LP.8. Its spread underscores how even in periods of lower national COVID concern, the virus continues to evolve and re-emerge.

The geographic footprint of Nimbus is widening. As of June 25, genetic sequencing data from GISAID—a global database for tracking virus evolution—confirms the presence of NB.1.8.1 in at least 18 U.S. states, including populous areas like California, Texas, New York, Illinois, and Virginia. Other affected states range from coastal hubs like Massachusetts to inland states such as Nebraska and Utah. Notably, experts caution that the real spread may be broader: due to decreased nationwide testing and reduced genomic sequencing, many infections may go unrecorded or untyped.

Internationally, the World Health Organization (WHO) flagged a rise in cases linked to this variant in Southeast Asia, the western Pacific, and the eastern Mediterranean, with NB.1.8.1 comprising nearly 11% of sequenced global samples by mid-May. These numbers represent a sharp jump from earlier in the spring and highlight the variant’s strong transmissibility. The U.S. initially detected Nimbus in airport screenings from travelers arriving from those same regions—an early sign of its global mobility.

What makes this particular spread pattern concerning isn’t necessarily the severity of the illness—experts agree Nimbus does not appear more virulent than past strains—but its efficiency in transmission. Changes to the virus’s spike protein may enhance its ability to infect human cells more readily. Combined with typical summer travel, relaxed precautions, and indoor gatherings in air-conditioned environments, the stage is set for continued expansion.

Still, national COVID levels remain relatively low according to CDC wastewater surveillance, even as experts forecast a possible summer wave. Historically, summer surges have occurred in both 2022 and 2023, and current trends suggest that 2025 could follow suit—especially if newer variants like Nimbus remain unchecked.

For public health officials, the focus now is not just on tracking case counts but also on raising awareness without inciting alarm. The spread of Nimbus is a reminder that the virus remains present, evolving, and capable of disrupting daily life if early symptoms are ignored or precautions are relaxed.

Should You Be Worried? Severity, Risk, and Vulnerable Groups

The rise of the NB.1.8.1 variant—now the dominant COVID strain in the U.S.—raises understandable questions: Is this something to be alarmed about? Could it lead to another wave of hospitalizations or serious illness?

For most people, the short answer is no, according to current data and expert consensus. Nimbus does not appear to cause more severe disease than its Omicron predecessors. While it may spread more easily due to mutations in its spike protein, it hasn’t been linked to higher rates of hospitalization or death in the general population. As Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University, puts it, “There’s no indication at this time that this variant leads to worse outcomes than what we’ve seen before.”

That said, low risk is not the same as no risk, especially for vulnerable groups. Older adults, people with weakened immune systems, and those with underlying health conditions remain at higher risk of complications if they contract COVID—regardless of the variant. Even if symptoms begin with something as seemingly minor as a sore throat, these individuals are more likely to develop serious respiratory issues or require hospitalization.

Vaccination remains one of the strongest lines of defense. Current COVID-19 vaccines are expected to offer protection against NB.1.8.1, particularly when it comes to preventing severe illness. However, vaccine uptake and guidance vary: while the CDC recommends updated 2024–2025 boosters for most adults and encourages discussions with pediatricians for children’s vaccinations, some public figures have stirred controversy by questioning vaccine guidance for pregnant women and healthy children—positions that have been widely criticized by the medical community.

Beyond vaccination, public health experts stress the importance of continued caution and self-awareness, especially during the summer months when COVID historically tends to resurge. Even mild symptoms like a scratchy throat or congestion shouldn’t be brushed off, particularly in mixed-age households or crowded environments.

There’s also the ongoing concern of long COVID, which can affect people of any age or risk category—even after a seemingly mild illness. As Dr. Alok Patel, pediatrician and medical contributor, noted: “Getting infected isn’t always life or death, but it can be very debilitating. It can affect your work, your family, and your long-term health.”

How to Protect Yourself This Summer

As the NB.1.8.1 “Nimbus” variant becomes the most common strain of COVID-19 in the U.S., experts are urging people to take practical, proactive steps—especially during the summer months when social gatherings, travel, and indoor cooling systems can all contribute to increased transmission. Here’s how you can stay safer without pressing pause on your life.

Stay Up to Date on Vaccinations

COVID-19 vaccines remain one of the most effective tools we have to prevent serious illness, hospitalization, and death. The 2024–2025 updated COVID booster is recommended for most adults by the CDC. For children and teens, parents are encouraged to consult with pediatricians to assess individual risk.

While breakthrough infections can still occur, especially with a highly transmissible variant like Nimbus, vaccinated individuals are far more likely to recover with mild symptoms. Staying current with vaccines helps reduce community spread and protect those who are immunocompromised or medically vulnerable.

Recognize Symptoms Early and Test Promptly

The now-familiar list of COVID symptoms—fever, fatigue, cough, congestion—still applies with Nimbus, but the razor blade sore throat may appear earlier and feel more intense.

If you develop any cold-like symptoms, especially sore throat, take a COVID-19 test promptly. Over-the-counter rapid tests remain effective, and isolating early can help prevent further transmission.

Improve Indoor Air Quality

Ventilation continues to be a powerful but often overlooked form of protection. When possible, open windows to increase airflow, especially in indoor spaces where people are gathering. Even small measures like using a HEPA air purifier or keeping fans near open windows can help dilute airborne virus particles.

Crowded and poorly ventilated indoor environments—offices, restaurants, movie theaters—can facilitate the spread of highly transmissible variants. If opening windows isn’t feasible, consider wearing a well-fitted mask, especially if local case numbers rise.

Practice Smart Hygiene and Etiquette

COVID fatigue is real, but foundational habits still matter. These include:

• Washing hands frequently or using alcohol-based hand sanitizer
• Covering your mouth and nose when coughing or sneezing
• Staying home if you’re sick—even with mild symptoms
• Avoiding touching your face, especially in public spaces

These simple steps help limit not only COVID-19 but also other summer viruses like RSV and the flu.

Travel Wisely

With summer travel in full swing, crowded airports and shared accommodations can increase exposure risk. Keep masks handy for crowded indoor areas, and sanitize surfaces in shared environments like hotel rooms or public restrooms.

If you’re traveling internationally or returning from a high-incidence area, consider testing upon return, especially if you’ll be around vulnerable loved ones.

Don’t Minimize Mild Illness

Finally, it’s important to avoid downplaying symptoms, especially in a season where allergies and colds are also common. As Dr. Patel warns, “Treating COVID like a nuisance instead of a health risk not only increases spread—it delays diagnosis, treatment, and the opportunity to protect others.”

Staying Vigilant Without Panic

The rise of the Nimbus variant—and its unmistakable “razor blade throat” symptom—is a timely reminder that COVID-19 continues to evolve, even if daily life has largely moved on. While this new strain doesn’t appear more dangerous in terms of severity, its rapid spread and uncomfortable symptoms reinforce the importance of staying alert, not complacent.

Fortunately, we are not starting from scratch. Tools like vaccines, rapid testing, and basic preventive measures remain effective and accessible. The goal now isn’t to live in fear but to live informed—ready to respond wisely if symptoms emerge, mindful of those at greater risk, and respectful of the virus’s continued presence in our communities.

This summer, as you travel, gather, or simply go about your daily routine, carry forward the lessons of the last few years: prioritize health, protect the vulnerable, and don’t ignore the signs—even if they start with just a sore throat.