Concern is rising over a new variant of coronavirus which is spreading, Health Secretary Sajid Javid as said.
Health experts first detected a version of the Delta variant of the disease - AY.4.2 - in July and it has been on the rise since then.
Known also as Delta Plus, it has so far not shown itself to be more dangerous than other variants but concern remains that it could develop into something more potent.
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At a Downing Street press conference on Wednesday, Health Secretary Sajid Javid urged people to get their Covid 19 booster vaccines as virus rates rise across the country, particularly in Greater Manchester.
And he expressed concern about AY.4.2.
He told the briefing: "Covid 19 mutates, like any virus, and we're identifying new variants all the time. This includes a new version of the Delta variant which is currently known as AY.4.2.
"And that new variant is now spreading.
"And while there's no reason to believe at this point that AY.4.2 poses a greater threat, the next variant or the one after that might do.
"So we need to be ready for what lies around the corner. This means our ongoing program of booster jabs is so important and this winter we're prioritising those most in need."
He said more than 4m people had now had their booster jab but he appealed for others to also get their boosters.
"We've got the jabs. We just need the arms to put them in," said the health secretary.
The press conference heard there were 7,891 people in hospital with Covid on October 19. Although the figure is rising, it remains well short of last winter's peak of almost 40,000 in February.
Some 139,000 people have now died in the UK within 28 days of a postive coronavirus test.
Last week there were an average 136 deaths per day and in the previous 24 hours there were 179 deaths.
