A new Covid-19 variant known as NB. 1.8.1 — informally referred to as ‘Nimbus’ — is drawing attention due to its unusual symptom: a sore throat described by some patients as feeling like ‘razor blades’. According to a June 11 report by Salon.com, the variant already accounts for more than 10 percent of recent cases across Asia and has also been detected in countries including the United States and Canada.

The World Health Organisation (WHO) has classified NB.1.8.1 as a Variant Under Monitoring (VUM). As a sub-lineage of the Omicron family, it is being closely tracked for changes in transmissibility or severity.

Citing Salon, the report noted that those infected with the variant often complain of an intensely painful throat. Other common symptoms resemble those of the flu, including nasal congestion, fatigue, mild coughing, muscle pain, fever and in some cases, gastrointestinal issues such as diarrhoea and nausea.

The Independent, in a June 10 report, quoted WHO officials as saying that the global risk from this strain is 'currently low' and that existing Covid-19 vaccines continue to be effective in preventing serious illness caused by the variant.

In terms of virology, Salon also reported that NB.1.8.1 has undergone at least three genetic recombination events involving other Covid-19 strains. While such recombination is a typical evolutionary behaviour in viruses, experts have expressed concern, warning that each recombination could potentially result in a variant with greater infectivity or increased disease severity.

Health authorities continue to advise standard precautions such as maintaining physical distance, following respiratory hygiene practices and adhering to public health advisories to help prevent the spread of NB.1.8.1.