A new strain of the virus that caused COVID to sweep the world has been detected in the UK. The Public Health Agency has confirmed that at least seven people in Northern Ireland have tested positive for the new variant , called NB.1.8.1. Experts are warning the strain may come with surprising symptoms not seen in earlier varients including heartburn, reports the Mirror. "Common symptoms include sore throat, fatigue, fever, mild cough, muscle aches and nasal congestion. Gastrointestinal symptoms may also occur in some cases," Dr Lara Herrero, Associate professor and virology research leader at Griffith University in Australia said. Gastrointestinal symptoms can include abdominal pain, bloating, nausea, vomiting, diarrhea, constipation and heartburn. The strain , now being monitored by the World Health Organisation (WHO), is already spreading in countries like China, the US, Australia and popular tourist hotspots including Thailand, Egypt and the Maldives. The full list of symptoms are; The WHO claims the variant is onw on their radar about data showed a huge rise in recent weeks, jumping from 2.5% to 10.7% of submitted global sequences in just four weeks, which has prompted growing international concern. 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." Experts say NB.1.8.1 carries multiple mutations that "may infect cells more efficiently than earlier strains ". Dr Lara Herrero explained: "It's possible a person infected with NB.1.8.1 may be more likely to pass the virus on to someone else, compared to earlier variants. The evidence so far suggests NB.1.8.1 may spread more easily and may partially sidestep immunity from prior infections or vaccination. These factors could explain its rise in sequencing data. "But importantly, the WHO has not yet observed any evidence it causes more severe disease compared to other variants. Reports suggest symptoms of NB.1.8.1 should align closely with other Omicron subvariants."