A new Covid variant Nimbus aka ‘razor blade throat’ is on the rise. All you need to know

The NB.1.8.1 variant has spread rapidly across China and Hong Kong, and cases have now been detected in several US states, including California, Washington, Virginia, and New York, according to an Associated Press report. Australia has also recorded cases. In the UK, 13 cases were confirmed in June, accompanied by a nearly 10 per cent rise in hospitalisations, The Independent reported. The variant and symptoms have also been detected in India.

By mid-May, NB.1.8.1 accounted for nearly 11 per cent of all sequenced COVID samples globally, signaling a rapid rise in circulation.

What are the symptoms?

The most reported and defining symptom of the Nimbus variant is a severely painful sore throat. Other symptoms include fever, chills, cough, shortness of breath, and loss of taste or smell. However, the World Health Organization (WHO) has stated that the variant does not appear to cause more severe illness than previous strains and is currently considered low risk.

What has WHO said?

The WHO has classified NB.1.8.1 as a “variant under monitoring,” indicating that while it is spreading, it doesn’t yet pose a major threat. The organisation has also confirmed that current COVID-19 vaccines remain effective in preventing severe outcomes linked to the variant.

“The WHO assesses the additional risk to the global public as currently low, and existing COVID-19 vaccines are considered effective in preventing severe disease,” Dr Naveed Asif, a general practitioner at The London General Practice, told The Independent.

Which vaccines offer protection?

Vaccines approved by the US FDA – Moderna, Pfizer-BioNTech, and Novavax – are expected to be effective against NB.1.8.1, especially because it belongs to the Omicron JN.1 lineage. An article by New York-Presbyterian/Columbia University Irving Medical Center stresses the importance of staying up-to-date with boosters.

Those with underlying health conditions like diabetes, heart disease, or hypertension should take extra precautions, as their immune response may not be as robust.

Why Nimbus spreads faster

Scientists believe NB.1.8.1 may spread more efficiently due to stronger binding with human cells. A Gavi report noted that the variant binds tightly to the ACE2 receptor, which SARS-CoV-2 uses to enter the body.

“Using lab-based models, researchers found NB.1.8.1 had the strongest binding affinity to the human ACE2 receptor of several variants tested,” said virologist Lara Herrero from Griffith University in The Conversation, “suggesting it may infect cells more efficiently than earlier strains.”

Dr Chun Tang, a general practitioner at UK-based Pall Mall Medical, added that while the variant isn’t drastically different from Omicron, “some tweaks to its spike protein” may make it more transmissible or help it evade immunity.

“What sets NB.1.8.1 apart is how quickly it spreads,” said Dr Magdalena Sobieszczyk, Chief of Infectious Diseases at New York-Presbyterian/Columbia. “It has a genetic advantage: mutations that make it easy for it to bind to receptors on human cells.”

Prevention is key

Precautions remain largely the same. Mask up in crowded places, cover your mouth while coughing or sneezing, wash and sanitise your hands regularly, and avoid stepping out if unwell. Ventilated spaces remain safer, especially during spikes in transmission.

No, ‘Nimbus’ isn’t a Harry Potter reference

While some may associate ‘Nimbus’ with the magical broomstick from ‘Harry Potter’ or characters from ‘Rick and Morty’, the nickname actually refers to a type of cloud. Professor T Ryan Gregory of the University of Guelph in Canada explained to Gavi’ that naming conventions like ‘Nimbus’ (NB.1.8.1) and ‘Stratus’ (XFG) help make emerging variants easier to track and communicate to the public.