People have started catching a new Covid variant that could soon take off and become the dominant type, according to scientists.
Identified in Germany, in June, cases of the XEC variant have since emerged in the UK, US, Denmark and several other countries, posters on X, formerly known as Twitter, say.
It has some new mutations that might help it spread this autumn, although vaccines should still help prevent severe cases, experts say.
For those more likely to become seriously ill from Covid, the NHS offers a free booster shot.
The vaccines have been updated to better match recent variants, although not XEC, which has emerged from earlier Omicron subvariants.
'Taking charge'
Director of the Scripps Research Translational Institute, in California, Eric Topol says XEC is "just getting started".
"And that's going to take many weeks, a couple months, before it really takes hold and starts to cause a wave," he told the LA Times.
"XEC is definitely taking charge.
"That does appear to be the next variant.
"But it's months off from getting into high levels."
What are the symptoms?
Symptoms are thought to be the same cold or flu-like ones as before:
- a high temperature
- aches
- tiredness
- a cough or sore throat
Most people feel better within a few weeks of Covid but it can take longer to recover.
There has been "strong growth" of XEC in Denmark and Germany - accounting for nearly one out of every five recent samples tested, Covid data analyst Mike Honey says on X.
In the UK, it is about one out of every 10.
There is far less routine testing than before, making it difficult to know how much Covid might be around.
The UK Health Security Agency says it is normal for viruses to mutate and change.
People qualifying for a free booster vaccine include:
- over-64s
- those living in a care home for older adults
- those over the age of six months in a clinical risk group
- some front-line NHS, care-home and social-care workers
The main vaccination drive for flu and Covid will start in October, although some may receive their shots earlier.