“Worst throat pain ever.”
“Like being burned by acid.”
“Couldn’t eat and could barely drink.”
That’s how users on Reddit have been describing their experiences with Nimbus, the latest Covid-19 variant sweeping through Asia and the United States alike.
Nimbus, or NB.1.8.1, has been designated a “variant under monitoring” by the World Health Organization (WHO) since May this year.
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The strain, which was first detected in China, has since spread across the continent and beyond, becoming the most common variant in the United States.
Here’s what you should know about Nimbus.
NB.1.8.1 is spreading fast
Nimbus, formally known as NB.1.8.1, is a subvariant of the Omicron variant (JN.1). As of May 2025, the strain had reached the shores of over 20 countries due to its higher rate of spread compared to other circulating variants. The WHO has determined that its risk level for growth is moderate due to its strong ability for transmission.
That said, there hadn’t been any acute cases of Nimbus as of their report in May. As such, WHO has concluded that its risk of severity is low.
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According to Kartik Cherabuddi, Chief Hospital Epidemiology Officer of the Tampa General Hospital, there have been no signs of Nimbus being especially powerful. “Early and limited laboratory data do not show a significant capability to evade the immune system or increased resistance to antiviral treatment,” he told Healthline.
WHO expects currently approved Covid-19 vaccines to remain effective against Nimbus’s risks of symptomatic and severe disease.
It causes “razor-blade throat” and other symptoms
Nimbus’s signature symptom, a sore throat, is characteristic of other Omicron variants as well. However, research has suggested that, of the prevalent strains today, Nimbus binds to ACE2 receptors the best, a mechanism that triggers the immune response and leads to symptoms like a sore throat.
However, the rest of its symptoms are similar to previous types of Covid-19, including fever, cough, reduced ability to taste or smell, and fatigue.
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In order to protect themselves from Nimbus, the same measures apply as for other Covid-19 variants: vaccination, handwashing, and staying away from carriers.
It is the most common Covid-19 subvariant in Macao
From January to May 2025, there have been 26 cases of cluster infections caused by Covid-19 in Macao. Of recent cases, most were caused by the Nimbus variant.
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For Covid-19 in general, the Macau Health Bureau (known by the Portuguese initials SSM) considers the virus “relatively active.” However, it noted that the current vaccine, designed to work against the Omicron variant, is effective in combating the strains currently in circulation. “No severe symptoms or other serious complications have occurred,” wrote the SSM.
