New Covid Variant ‘Nimbus’ Spreads In US, Causes Painful ‘Razor Blade Throat’. What Is It?

Last Updated:June 18, 2025, 18:07 IST

Known scientifically as NB.1.8.1, the variant is currently being monitored by the World Health Organization (WHO) and was first detected in China earlier this year.

Nicknamed “razor throat,” the symptom of the Nimbus variant is an intensely painful sore throat.

A newly emerging Covid-19 subvariant ‘Nimbus’ is gaining ground in the United States, causing a distinctive and extremely painful sore throat, commonly described by patients as “razor blade throat." Known scientifically as NB.1.8.1, the variant is currently being monitored by the World Health Organization (WHO) and was first detected in China earlier this year. According to data from the Centers for Disease Control and Prevention (CDC), Nimbus accounted for approximately 37% of US cases in the two-week period ending June 7. The variant could soon represent up to one-third of global Covid cases, health officials have warned.

Painful New Symptom Owing To Nimbus

Nicknamed “razor throat," the symptom of the Nimbus variant is an intensely painful sore throat, with some patients likening it to “swallowing shards of glass." This symptom is notably more severe and more common than in previous variants as Dr. Marc Siegel, Fox News’ senior medical analyst, said, “Many of the Covid subvariants have characteristic features. Nimbus is being associated with an unusually sharp sore throat."

Other symptoms reported include: nasal congestion or runny nose, fatigue, mild cough, fever, muscle or body aches and nausea or diarrhea. Despite the striking throat pain, Dr. Marc Siegel said that Nimbus does not appear more virulent than earlier strains.

Dr. Kenneth Perry, an emergency room physician in South Carolina, noted that the predominant symptoms of Covid continue to shift with each new variant, saying, “With the new variant, it appears that the sore throat is yet again a prominent symptom. The pain is caused by direct infection and inflammation of the throat’s cells."

What US Health Agency Has Said On Nimbus?

Though the variant is clearly spreading, the CDC noted that NB.1.8.1 is still emerging in terms of genetic sequencing data. A CDC spokesperson told Newsweek that fewer than 20 confirmed genetic sequences of the variant had been documented in US baseline surveillance so far while public health officials remain alert to its rise, particularly in high-population states like California and New York.

Dr. Tyler B. Evans, infectious disease expert and CEO of the Wellness and Equity Alliance, said that while Nimbus may not drastically differ from other recent strains, it should still be taken seriously. “We’re still seeing the familiar signs—sore throat, nasal congestion, fatigue, cough," he told Newsweek, adding, “But in some people, especially the unvaccinated, this can escalate into more severe respiratory symptoms."

Mallika Soni

When not reading, this ex-literature student can be found searching for an answer to the question, "What is the purpose of journalism in society?"

When not reading, this ex-literature student can be found searching for an answer to the question, "What is the purpose of journalism in society?"

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News world New Covid Variant ‘Nimbus’ Spreads In US, Causes Painful ‘Razor Blade Throat’. What Is It?