People aged 32 and 33 in England are now being invited to book their first dose of the coronavirus vaccine.
The NHS said booking will open to that age group – about one million people – at 07:00 BST on Saturday.
Text message invitations will be sent out to 33-year-olds on Saturday and also to 32-year-olds on Monday.
More than 37.5 million people in the UK have now received their first dose of the jab – and 21.6 million second doses have been given.
The other UK nations are already offering jabs to younger age groups – people aged 30 and over are eligible in Scotland, over-18s in Wales and over-25s in Northern Ireland.
It comes as Heathrow Airport has decided to open a separate terminal just for passengers arriving from “red list” countries, after concerns that travellers from red countries were queuing up with people from destinations with lower instances of Covid.
Although the UK government is still advising against non-essential travel to most countries, some European nations are indicating whether UK tourists will be allowed in.
Germany has announced that anyone arriving from the UK will have to quarantine for two weeks. German officials said the decision was related to the Indian Covid variant, which is currently spreading in some parts of the UK.
But Spain is officially lifting restrictions for UK tourists from Monday, and arrivals will not need a PCR test.
More than 40% of adults in England have now had both doses of the vaccine – meaning they have maximum protection from the virus.
And among those aged 35 to 39, more than half have had their first jab, since becoming eligible earlier this month.
Health Secretary Matt Hancock said the government was still on track to offer a vaccine to everyone by July.
Text invitations will appear as a message from “NHS vaccine”, and people who cannot go online can call 119 to book a jab.
People in their 30s and pregnant women are being offered either the Pfizer-BioNTech or the Moderna vaccines if they are available, rather than the Oxford-AstraZeneca jab, because of concerns about a possible link between the Oxford jab and rare blood clots.
And over-50s and those considered clinically vulnerable will have their second doses brought forward to after eight weeks, rather than twelve, following concerns about the Indian variant.
Latest government figures on Friday showed there had been another 2,829 confirmed cases of the virus in the UK, and a further nine deaths.
There were also early signs of a “potential increase” in Covid infections in England, the Office for National Statistics said on Friday – following a fall for five straight weeks.