A new COVID-19 subvariant, known scientifically as NB.1.8.1 and colloquially dubbed “Nimbus,” has gained widespread attention in recent weeks. Health professionals have observed a distinct and alarming symptom among many infections: an extremely painful sore throat, described evocatively as a “razor blade throat.” Although this dramatic symptom has captured headlines, experts emphasize that overall disease severity appears to remain comparable to that of earlier Omicron subvariants.
A New Warning Sign: Razor Blade Throat
What sets this variant apart is the signature throat discomfort. Numerous people infected with Nimbus have shared descriptions likening the sensation to swallowing razor blades, shards of glass, or having severe rawness behind the throat. For some, this intense discomfort lasts several days, beginning with mild scratchiness and escalating to an almost unbearable burning sensation. Reports also include difficulty swallowing—sometimes disrupting sleep and causing panic. Yet, beyond throat pain, most other Nimbus-related symptoms follow familiar COVID patterns: mild fever or chills, intermittent cough, nasal congestion, fatigue, headaches, and occasional muscle aches.
Transmission, Prevalence, and Global Reach
NB.1.8.1 has now been detected across several continents. It first appeared in parts of China and Asia in early 2025, and has since spread to regions including Southeast Asia, the eastern Mediterranean, the western Pacific, parts of Europe, North America, and particularly California and other U.S. states such as New York, Texas, Illinois, Washington, and Virginia. Recent data suggest that by mid‑June, Nimbus accounted for roughly 10% to 40% of newly sequenced COVID cases in various jurisdictions. The World Health Organization (WHO) has classified it as a “variant under monitoring.” Importantly, there is no current evidence indicating it causes more severe illness or higher hospitalization rates than existing Omicron-derived variants.
Why the Distinct Throat Pain?
While sore throat has always been a recognized symptom of COVID, the dramatic intensity seen with Nimbus appears to be more than anecdotal. Early studies point to specific mutations in its spike protein that might enhance the virus’s ability to bind to throat tissues, leading to more aggressive inflammation and irritation. Nonetheless, this intense throat pain remains one symptom among many, and not every infected individual experiences severe throat discomfort.
Vaccines, Immunity, and Public Health Guidance
Current COVID-19 vaccines continue to offer protection against severe disease, hospitalization, and death from NB.1.8.1. Booster doses are still recommended, especially for high-risk populations such as older adults, people with weakened immune systems, and pregnant individuals. Some countries have recently shifted their vaccination policies—for example, modifying recommendations for children and pregnant women—which has led to thoughtful debate among healthcare providers. Regardless, public health experts stress that vaccination remains a critical defense, particularly to minimize the risk of complications like long COVID.
If you experience an intense sore throat that feels unusually sharp or burning—especially if coupled with other respiratory symptoms—seek testing for COVID-19 as well as strep throat or other throat infections. For mild, home-manageable cases, standard self-care applies: rest, hydration, throat lozenges or warm saltwater gargles, over-the-counter pain relief, and isolation to prevent transmission. Individuals in high-risk categories should monitor symptoms closely and seek medical attention if they experience breathing difficulty, chest pain, persistent fever, or prolonged symptoms beyond a week.
The emergence of NB.1.8.1—and its “razor blade throat” effect—underscores that COVID-19 continues to evolve in ways that can surprise us. Even if overall disease severity hasn’t increased, novel symptoms and shifts in transmissibility mean that continuous vigilance, testing, and immunization remain vital. As experts track mutation patterns, monitoring changes in symptom profiles and regional prevalence helps maintain effective public health responses.
The Nimbus variant has introduced a new, vividly described symptom into the public lexicon: the razor blade throat. While symptoms can differ widely and most people recover at home, its rapid spread emphasizes the ongoing reality that COVID-19 is not yet routine. Protect yourself and others by staying informed, staying vaccinated, and staying ready to test or isolate if symptoms appear. Even as the pandemic enters new phases, key measures—vaccination, hygiene, masks in risky settings—remain our best tools against evolving threats.
