NB.1.8.1 COVID Variant Detected in UK: What Sets 'Nimbus' Apart

NB.1.8.1 COVID Variant Detected in UK: What Sets 'Nimbus' Apart

Jul, 10 2025

New COVID-19 Variant NB.1.8.1 Emerges in the UK

This summer isn’t just about heatwaves and holidays. The UK Health Security Agency has spotted a new COVID-19 variant, NB.1.8.1—nicknamed 'Nimbus'—making its rounds in the country. It’s not causing panic yet, but experts aren’t exactly sitting back and relaxing.

Why all the buzz? Well, this isn’t just another copy of Omicron. Early signs suggest NB.1.8.1 is even better at spreading than previous strains, showing a knack for latching onto our cells more tightly. It's now flagged as a 'variant under monitoring' by the World Health Organization, which is code for: keep a close eye on this one.

Unlike the usual headache, cough, or sore throat you might expect, NB.1.8.1 is showing up with some stomach-turning symptoms. People have reported nausea, vomiting, diarrhoea, heartburn, bloating, constipation, and stomach pain—plus all the regular suspects like fever, dry cough, tiredness, and trouble breathing. So, if you suddenly find yourself running to the bathroom more than usual, and you’ve got COVID-like symptoms, don’t brush it off.

What We Know About Transmission, Severity, and Vaccines

Lab studies are pointing out that NB.1.8.1 is pretty good at sticking to ACE2 receptors on human cells, the same doorways past versions of the virus have used. That basically means it could be easier to catch and spread. What’s a little less clear so far is whether it makes people sicker than before. Thankfully, there isn’t any solid evidence showing it’s more dangerous than earlier waves.

This new variant has a few tweaks to its spike protein. That could help it sneak by some of our immune defenses, especially for people who haven’t had a recent booster or infection. But the vaccines are still doing their job at protecting against hospital stays and the most serious cases—something health officials want to hammer home as cases quietly climb.

Public health experts like Dr Neil O'Brien and Dr Michael Gregory are urging anyone at high risk—think people over 75, care home residents, or folks with a weakened immune system—to get vaccinated straight away. Spring booster numbers have been lower than hoped, which has raised some eyebrows among doctors. The message is clear: don’t wait until the virus is knocking on your door.

  • JCVI says those over 75, care home residents, and immunosuppressed people are the priority for autumn vaccines.
  • Spring booster campaigns are wrapping up, so the window’s closing fast for eligible groups.
  • International cases of NB.1.8.1 are rising, with at least 22 countries reporting the variant.

So, what does this mean for the day-to-day? NB.1.8.1 looks like it could move fast, and it’s popping up in more places worldwide. Scientists are watching it closely for any signs the situation’s changing. For now, sticking with the vaccine guidance and paying attention to both new and old symptoms will help keep things under control.