People in their 40s could get their coronavirus vaccine from Tuesday as the second stage of the vaccine rollout is expected to start imminently.
Reports suggest that some healthy adults in their 40s could be offered the jab from tomorrow after the Government has met its target for offering the vaccine to over 50s and those deemed clinically vulnerable.
But supply constraints could mean that many may have to wait a little longer to be offered the jab.
In March the NHS in England warned of a "significant reduction in weekly supply" throughout April, meaning volumes for first doses will be "significantly constrained".
It said people "aged 49 years or younger should not be offered vaccination" unless they are in a higher priority group, such as being clinically vulnerable.
It is understood that the guidance still stands.
Throughout April the health service has prioritised second doses of the Pfizer and AstraZeneca vaccines and a record 475,230 people received their second jab on Saturday.
So far almost 40 million vaccinations have been delivered across the UK, this includes 32 million first doses and almost 7.5 million second doses.
The Government set a target of the middle of April to offer a first dose of vaccine to everybody in the top nine priority groups, also known as phase one of the vaccination programme.
And earlier this month the NHS urged anyone who is eligible for a Covid-19 vaccine to book one immediately and for people to turn up for second doses when called.
In England around 94% of people aged 50 and over in England are likely to have had their first dose of Covid-19 vaccine.
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And around 92% of those identified as clinically extremely vulnerable have had their first jab.
Phase two of the programme will see the vaccine offered to younger healthy adults, starting with those aged 40 to 49.
In the UK, regulators have recommended that people aged 18 to 29 should be offered alternatives to the AstraZeneca vaccine, saying there was a possible link between the jab and "extremely rare" blood clots.
This means that they could be offered the Pfizer or Moderna jabs.
The Department of Health and Social care confirmed that doses of the Moderna vaccine will be rolled out in England from "mid April" after first doses were already delivered in Wales and Scotland.