Covid-19, it seems, can never stay out of the news for very long. One variant of the virus has been making headlines recently for being behind a spike in cases, particularly in China and the United States, and for causing ‘razor blade’ throats, or a severely painful sore throat. What do you need to know about this? Read on, to find out.

The ‘razor blade’ throat, reports indicate, is being caused by the NB.1.8.1 variant of the virus, an Omicron-descendent variant dubbed as ‘Nimbus’ and currently accounting for a large number of cases worldwide.

On May 23, 2025, the World Health Organization classified this variant as a “SARS-CoV-2 variant under monitoring (VUM) with increasing proportions globally, while LP.8.1 is starting to decline.” A technical document by the WHO states: “Considering the available evidence, the additional public health risk posed by NB.1.8.1 is evaluated as low at the global level. Currently approved COVID-19 vaccines are expected to remain effective to this variant against symptomatic and severe disease. Despite a concurrent increase in cases and hospitalizations in some countries where NB.1.8.1 is widespread, current data do not indicate that this variant leads to more severe illness than other variants in circulation.”

Symptoms remain similar to those caused by other Covid-19 strains and include fever, a sore throat, cough, runny nose and tiredness. Media reports indicate some patients complaining of a sharp, stabbing pain while swallowing, often at the back of the throat, akin to ‘swallowing a razor blade’. However, it is unclear if this is a distinctive symptom of this variant

The WHO, in its technical document, had said spike mutations in this variant could increase its transmissibility.

In India, according to data from the Indian SARS-CoV-2 Genomics Consortium (INSACOG), one case of NB.1.8.1 was identified in April in Tamil Nadu and four cases of LF.7 were detected in Gujarat in May. As of May, the most common variant remained JN.1, comprising 53 % of samples tested, followed by BA.2 (26 %) and other Omicron sublineages (20 %). In June, a media report stated about 163 cases of the COVID-19 variant XFG, had been detected, according to INSACOG data.

Earlier this week, Naveen Kumar, Director, National Institute of Virology (NIV), Pune, said surveillance and genome sequencing have been scaled up. He said genomic analysis had revealed the surge was due to the JN.1.16 sub-lineage of the Omicron variant, and that since May 2025, it had been replaced by the XFG (LF.7 and LP.81.2) recombinant variant.

Doctors in India have reiterated that Covid-19 is now co-circulating with other seasonal infections and that they do not expect any major waves of the kind seen in 2021 and 2021. Spikes and dips however, may continue. Personal protection and hygiene measures such as hand washing, avoiding crowded places when possible or masking up, and protecting vulnerable segments of the population must continue, they have said.

As of Friday, June 20, 2025, India’s tally of active Covid-19 cases dipped to 5,608 from the 7,000 plus mark last week, and four new deaths were reported, taking the total toll this year to 120.

Published - June 20, 2025 04:51 pm IST