A new coronavirus strain has prompted health chiefs to issue a "stay at home" warning if people start to feel unwell.
The BA.2.86 variant, known as Pirola, has now been detected in the UK.
Following the discovery of the new variant, health experts have brought forward the rollout of the latest Covid booster vaccination as a precaution.
Medics are now urging anyone who feels unwell and unsure if they have Covid to avoid contact with vulnerable people at stay at home if possible.
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The UK Health Security Agency (UKHSA) says it is unsure how serious the strain will be.
Chiefs advise anyone with symptoms of a respiratory infections, such as Covid, a high temperature or do not feel well enough to go to work should stay at home.
Britons aged 65 and over and those in a clinical risk group are being urged to take up the Covid booster vaccine.
The UKHSA said: "Vaccines remain our best defence against severe disease and hospitalisation from flu and COVID-19.
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"That’s why we’re asking over-65s, anyone in a clinical risk group, and anyone living in a household with someone who is in a clinical risk group, to come forward for their vaccination.
"Their protection since their last vaccination will have waned and they remain at increased risk from a respiratory infection this winter.
"It’s also important to note that Covid-19 isn’t a special case; respiratory infections can be unpredictable, and we’re asking similar groups to get vaccinated against flu."
The UKHSA added that people should get vaccinated ahead of the winter season as it can take a few weeks for protection to build.
Britons aged 65 and over and those in a clinical risk group are being urged to take up the Covid booster vaccine
PA
Scientists are currently working with vaccine developers to get samples of new vaccines to assess whether they will better protect against the virus, the UKHSA said.
It added: "Vaccinations for flu and Covid-19 will give us good protection ahead of winter, when respiratory illnesses circulate in all our communities.
"They will help to keep vulnerable people out of hospital and carrying on with their day-to-day lives, as well as reduce pressure on our NHS which is always critical in the winter.
"If you’re eligible for the jabs, please don’t hesitate, book your vaccine and get winter strong."
