The UK’s COVID alert level has been raised to its second highest following a rapid increase in cases of the Omicron variant.
The country’s four chief medical officers have recommended to ministers that the UK moves from level 3 to 4.
The CMOs warn Omicron is spreading much faster than Delta and there is less vaccine protection against symptomatic disease from the new variant.
They also said that people are already in hospital due to Omicron and the number of patients is “likely to increase rapidly”.
On Sunday, the UK reported 1,239 additional confirmed cases of Omicron – the highest daily rise and nearly double the previous high recorded on Saturday.
That takes the total numbers of cases of the variant to 3,137 in the UK.
The alert level upgrade means health authorities think rates of transmission are high and pressure is being placed on healthcare services.
It comes as Prime Minister Boris Johnson is set to give an address to the nation later this evening on the COVID vaccine booster programme.
The CMOs and NHS England’s Professor Stephen Powis said the emergence of Omicron “adds additional and rapidly increasing risk to the public and healthcare services”.
In a statement, they said: “Transmission of COVID-19 is already high in the community, mainly still driven by Delta, but the emergence of Omicron adds additional and rapidly increasing risk to the public and healthcare services.
“Early evidence shows that Omicron is spreading much faster than Delta and that vaccine protection against symptomatic disease from Omicron is reduced.”
They added: “Data on severity will become clearer over the coming weeks but hospitalisations from Omicron are already occurring and these are likely to increase rapidly.”
The medical officers say when vaccine protection is reduced – as is the case with Omicron – is it is “essential” that people top up with a booster jab.
They have said both booster vaccines (Pfizer and Moderna) increase the immune response substantially and show good effectiveness although with some reduction compared to Delta.