Nimbus and Stratus: New COVID-19 variants spreading in the UK
This autumn (2025), the UK is seeing another rise in COVID-19 cases, mostly because of two new variants—Nimbus (NB.1.8.1) and Stratus (XFG).
These two are now behind a high proportion of infections, but the good news is they aren't causing more severe illness or higher death rates than earlier versions.
Symptoms and at-risk groups
Stratus often brings a hoarse voice, while Nimbus can feel like a razor blade sore throat.
Both also show up as headaches, coughs, congestion, and fatigue—so they're easy to mix up with a regular cold or flu.
Cases are climbing fastest among young kids and older adults.
What to do if you catch the virus?
Health officials recommend isolating if you have symptoms, wearing masks in public if you have symptoms and need to leave the house, and keeping up with hand hygiene.
Free NHS COVID shots are still available for people 75+, plus there are flu and RSV vaccines for extra protection this winter.
While free COVID tests have ended, you can still get tests or private vaccines at pharmacies.
Reinfections happen but tend to be mild—vaccines remain your best bet for avoiding serious illness.