People aged 45 or over in England will now be invited to get a Covid jab, Health Secretary Matt Hancock has said.
The vaccination programme would then move on to everyone aged 40 or over “in line with supplies”, he added.
Appointments can be made on the NHS booking website, which temporarily crashed on Tuesday morning when it opened up to the new age group.
First Minister Nicola Sturgeon also confirmed over-45s would start to get invites in Scotland this week.
Unlike in England, appointments there will be allocated and there are no plans to introduce an online booking service.
In Northern Ireland, people aged 40-45 are eligible to get a Covid vaccine, while in some areas in Wales 40-49 year-olds are being invited.
All over-50s and those in high-risk groups in the UK have been offered a first dose of the vaccine.
In other developments:
- England joined Wales and Scotland in giving out its first doses of the Moderna jab, the third vaccine administered in the UK
- Government vaccine adviser Prof Jeremy Brown told the BBC people will eventually “have to” mix Covid jabs
- Scotland speeded up its easing of domestic travel restrictions in light of declining case numbers
- Johnson & Johnson confirmed it will delay the rollout of its one-dose jab in Europe, amid a pause in the US, after reports of extremely rare blood clots
The UK has bought millions of that vaccine, also known as Janssen, but the Department of Health said the delay would not affect the UK’s vaccine efforts.
A further 2,472 coronavirus cases were recorded across the UK on Monday, with a further 23 deaths within 28 days of a positive test reported.
Meanwhile, Prime Minister Boris Johnson has warned that coronavirus infections and deaths will start to rise again as restrictions were eased.
He said that although the vaccination programme had helped reduce the numbers, “the bulk of the work in reducing the disease has been done by the lockdown” and he urged people to be “cautious”.
However, he said he could not see any reason to change England’s roadmap out of lockdown. Mr Johnson added that he was “very confident” about the UK’s vaccine supplies.
- When will over-40s get the jab?
- How many people have been vaccinated so far?
- UK sets new record for Covid jab second doses
Mr Hancock said the government was “on track” to offer a vaccine to everyone aged 18 or over by the end of July after meeting an earlier target for offering jabs to the most vulnerable.
Speaking in the House of Commons, Mr Hancock hailed the “remarkable achievement” of delivering more than 40 million vaccine doses and fully vaccinating 7.8 million people.