The COVID vaccination programme is being expanded to younger age groups as the government launches a campaign to encourage people under the age of 50 to get the jab.
In England, 44-year-olds are next in line, with invitations sent out to around 500,000 people from today.
More than two-thirds of those aged 45 to 49 have already been vaccinated and the decision to move to people aged 40 to 43 will be set out in the coming days.
Since the vaccination rollout began in December, more than 28 million people have been vaccinated with a first dose in England, 63.8% of the total population of adults aged over 18.
In Northern Ireland, the vaccination will be fully open for those aged 35 to 39, following some limited availability for this age group last week.
The government campaign is a 60-second video, with a cover of Dinah Washington's What A Difference A Day Makes recorded by songwriter and artist Shells, has been produced for the effort.
It shows people across the UK getting their COVID vaccines, as well as the healthcare workers who administer them.
The plan is for the advert to both encourage people under 50 to get a coronavirus shot, and also remind those who have already had a jab of the need to get their follow-up dose.
So far, 33,666,638 first vaccinations have been given out in the UK.
And with 12,587,116 second doses administered, a total of 46,253,754 jabs have been given out.
Health Secretary Matt Hancock said: "Vaccines are helping us get back to doing the things we have missed - they protect you and those around you.
"This campaign is a remarkable and poignant reminder of everything we've been through as a country and everything we have to look forward to - as well as the tireless efforts of our volunteers, NHS heroes and the British people.
"Every vaccination gives us hope and I urge everyone to take up the offer of a vaccine when it comes, as we continue on the path back to normality."
The campaign - called "every vaccination gives us hope" - will also appear on radio, multicultural media, social media and billboards.
The TV advert will first be aired at 7.15pm on ITV on Monday, during Emmerdale.
It comes with vaccine hesitancy in the UK said to be highest in 16 to 29-year-olds, according to figures from the Office for National Statistics (ONS).
Some 12% of people in this age group said they had declined the vaccine, were unlikely to have the jab if offered, or did not know if they would have a vaccination in a survey carried out earlier this year.
This is the equivalent to roughly 1.2 million people, based on analysis of the figures by the ONS.
Hesitancy was 9% among those aged 30 to 49 - equivalent to 1.6 million people.
The government says that since they and the NHS published the vaccine uptake plan in February, the take-up of jabs from people of all ethnic minority backgrounds has tripled.
Among people from a Pakistani background, uptake is four times higher than in February, and from those of Bangladeshi heritage, it is five times higher.
Meanwhile, researchers are recruiting 4,000 volunteers to take part in a study trialling a new coronavirus vaccine by Valneva.
Early trials have shown the vaccine to be "well tolerated with no safety concerns identified" and recruitment for the final phase of trials will begin at the end of April.
It will run across 22 sites in England and two in Scotland and is open to healthy adults who have not had previous COVID-19 vaccines.