The target of offering a first COVID vaccine dose to the nine most vulnerable groups by 15 April has been reached, the government has said.
Ministers had vowed to offer a COVID-19 jab to all over-50s, the clinically vulnerable and health and social care workers – about 32 million people – by Thursday.
The target – for the whole of the UK – was reached three days early and means adults under 50 will start to be invited for their first jab "in the coming days", Number 10 said.
Nearly 40 million vaccine doses have now been given across the UK.
This includes 32,190,576 first doses and 7,656,205 second doses.
The Joint Committee on Vaccination and Immunisation (JCVI) is expected to publish advice on when those aged under 50 should be invited for their first doses as part of the next phase of the rollout.
People in their late 40s in England will be the first to be invited to book their jabs, it is understood.
The devolved governments in Wales, Northern Ireland and Scotland will decide with the NHS how to implement the JCVI’s advice.
Last week, the Moderna vaccine became the third jab – along with the Oxford-AstraZeneca and Pfizer vaccines – to begin being used in the UK.
Elle Taylor, from Ammanford in Wales, who is an unpaid carer for her 82-year-old grandmother became the first person in the UK to have the Moderna jab. On Tuesday the NHS in England will also begin to use it.
In all the UK has purchased 17 million doses of the Moderna vaccine, enough for 8.5 million people.
Prime Minister Boris Johnson said: "We have now passed another hugely significant milestone in our vaccine programme by offering jabs to everyone in the nine highest risk groups.
"That means more than 32 million people have been given the precious protection vaccines provide against COVID-19.
"I want to thank everyone involved in the vaccine rollout which has already saved many thousands of lives.
"We will now move forward with completing essential second doses and making progress towards our target of offering all adults a vaccine by the end of July."
The government reached its primary vaccine target – to offer a first dose to priority groups one to five – in mid-February.
Mr Johnson has since promised all adults will be offered a vaccine by the end of July.
Ministers have offered assurances that this timescale will not be delayed by last week’s recommendation for under-30s to be offered an alternative to the Oxford-AstraZeneca jab due to concerns over blood clotting.
The Medicines and Healthcare products Regulatory Agency (MHRA) said those aged 18-29 in the UK will be offered an alternative vaccine instead, where available, when invited to get a jab.
What are the nine priority vaccine groups?
1. Residents in a care home for older adults and staff working in care homes for older adults
2. All those 80 years of age and over and frontline health and social care workers
3. All those 75 years of age and over
4. All those 70 years of age and over and clinically extremely vulnerable individuals (not including pregnant women and those under 16 years of age)
5. All those 65 years of age and over
6. Adults aged 16 to 65 years in an at-risk group
7. All those 60 years of age and over
8. All those 55 years of age and over
9. All those 50 years of age and over