Boris Johnson has urged the nation to "get boosted now", as daily recorded Covid cases hit a record high.
The prime minister said booster jabs were vital in slowing the spread of the new Omicron variant and averting hospitals being overwhelmed this winter.
The UK recorded 78,610 new cases on Wednesday, beating the previous record of 68,053 cases recorded on January 8 - when the UK was in lockdown.
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Mr Johnson said: "It's absolutely vital that you get jabbed because the wave of Omicron continues to roll in across the whole of our United Kingdom.
"The doubling rate of Omicron in some regions is now down to less than two days and I'm afraid we're also seeing the inevitable increase in hospitalisations, up by 10% nationally week on week."
The comments came as the head of the UK Health Security Agency, Dr Jenny Harries, warned the Omicron variant is "probably the most significant threat" since the pandemic began.
Mr Johnson, speaking at Number 10 press conference, said: "Let's keep giving Omicron both barrels, let's slow its spread and give the vaccines more time, wear face masks indoors, or use ventilation.
"Get tested if you're going to an event where you're likely to meet lots of people and get tested if you're going to meet elderly or vulnerable relatives."
Meanwhile Health Secretary Sajid Javid has refused to rule out the reintroduction of more restrictions in the coming weeks, but insisted the steps currently in place “are the right ones”.
Asked whether more guidance would be issued – rather than legislation – he told reporters: “We keep the whole situation under review. It is fast-moving, I think people understand that.
“The case numbers are still sadly rising rapidly, we have been very open about how quickly this new variant spreads, we have seen it double in terms of infections every two to three days across the country.
“We are buying time to assess this virus and build our defences.”
Pressed on whether people should prepare for new restrictions in the new year, Mr Javid replied: “You should be preparing yourselves to get boosted.”
