England manager Gareth Southgate is urging younger people to get vaccinated, saying it is a chance to "get your freedom back".
It comes after it was revealed the proportion of people aged 20 to 29 testing positive for Covid in England had hit record levels.
In the message, released by 10 Downing Street, he said vaccination was "our best route out of this problem".
Many young adults have not received a first vaccine dose yet.
About 34% of 18 to 29-year-olds in England - about three million people - have not been vaccinated at all. In Scotland, about 30% are not yet vaccinated.
But half of all under-30s in England - more than four million people - received a first dose in the three weeks after the vaccination programme was opened to people in their 20s in June. And the vaccination rate is still climbing for this group in England and Scotland.
Southgate started by thanking fans for their support of the England team at Euro 2020, before saying: "We know the last 18 months have been incredibly difficult for everybody.
"And there's no doubt that the vaccination programme is our best route out of this problem, not only for us as a country but across the world.
"So I just wanted to say how important it is, if you haven't had your vaccine yet, to go and get it done."
He said "oldies" like him could now "crack on" with their lives if they were fully vaccinated, adding that "for you younger ones especially, it's the chance for everything to open up, to get your freedom back".
The former England player continued: "So much of that is going to rest on you having the vaccine.
"So, don't put it off any longer, go and get it done, we can open everything up, we can protect the people we need to protect and you guys will get your freedom back."
The video has been shared widely on social media.
Public Health England's figures show, in the last week, 1,155 people in their 20s tested positive for every 100,000 in the population.
That is the highest rate of cases in any age group since mass-testing began, experts said, urging everyone in this group to get both jabs.