What is new Covid variant NB.1.8.1? Symptoms as cases confirmed in UK

Covid-19 is once again making headlines more than five years after the initial outbreak, with a new variant confirmed in the UK and in several countries across the globe.

The new strain, named NB.1.8.1, now accounts for just over 10 per cent of global infections , with cases now confirmed in Northern Ireland and Wales.

While there is no evidence that the new strain causes more severe symptoms, experts believe that it in can infect cells more efficiently and can trigger gastrointestinal symptoms such as diarrhoea, constipation and nausea.

Since first being recognised in January 2025, the omicron variant has spread to several states across the US, Australia, Thailand and is the most dominant variant in China and Hong Kong.

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The World Health Organisation has designated the NB.1.8.1 as a “variant under monitoring”, and comprises around 10.7 per cent of all submitted sequences.

A WHO spokesperson said: "SARS-CoV-2 continues to evolve, and between January and May 2025, there were shifts in global SARS-CoV-2 variant dynamics. At the beginning of the year, the most prevalent variant tracked by WHO at the global level was XEC, followed by KP.3.1.1.

"In February, circulation of XEC began to decline while that of LP.8.1 increased, with the latter becoming the most detected variant in mid-March. Since mid-April, the circulation of LP.8.1 has been slightly declining as NB.1.8.1 is increasingly being detected."

While it first appeared in samples at the beginning of this year, data from GISAID, a global data of genetic sequences of major disease-causing viruses, show that the first known cases were registered at the end of April.

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While evidence has suggested that NB.1.8.1 may spread more easily than other variants, the WHO has not observed any signs that it has an increase in severity.

"Data indicates that NB.1.8.1 does not lead to more severe illness compared to previous variants, although it appears to have a growth advantage, suggesting it may spread more easily," Subhash Verma, a professor of microbiology and immunology at the University of Nevada, Reno School of Medicine, told CBS News.

"In other words, it is more transmissible."

Common symptoms align with typical Omicron subvariants and include fatigue, fever, muscle aches and a sore throat.

So far, cases have been recorded in both Northern Ireland and Wales, as well as in popular British tourist hotspots overseas. However, given the dwindling numbers in people testing for Covid-19, it has become increasingly difficult to know the true number of infections.

Current Covid jabs are expected to remain effective against this variant and protect anyone infected from severe illness.