Boris Johnson has said he is not planning on introducing so-called vaccine passports for going to the pub – but indicated proof of a jab is likely to be needed for some international travel.
Speaking to the media from south London on Monday morning, the prime minister said proof of a vaccine would probably not be required for day-to-day activities.
He said: “I think inevitably there will be great interest in ideas like 'Can you show that you had a vaccination against COVID?' in the way that you sometimes have to show you have had a vaccination against yellow fever or other diseases in order to travel somewhere. I think that is going to be very much in the mix down the road.
"I think that is going to happen.
“What I don’t think we will have in this country is – as it were – vaccination passports to allow you to go to, say, the pub or something like that. I think that that would be going it a bit.”
His comments come amid a growing sense that some sort of vaccine passport will be needed in future for international travel – with those with one enjoying a "fast track" when they go on holiday.
Watch: Boris Johnson on the future of vaccine passports
On Monday, Spain's foreign minister Arancha Gonzalez said a possible scheme could mean those who cannot provide certification would instead need to go through testing and find it harder to get around.
Speaking on BBC Radio 4 on Monday, Gonzalez said: "People with a vaccine certificate are in the lower risk versus other people who are may be in the higher risk and would have to go through the ordinary procedures of PCRs, tests and the rest.
"But, of course, there could be some sort of fast track for people who have gotten their vaccine – and can prove it with a certification – that would have it easier to move around where mobility would be easier, simply because they are in the lower risk category.
"This is a scheme that Spain together with a group of other countries are working on."
Health secretary Matt Hancock confirmed on Monday that the UK was one of those countries talking about a certification scheme. However, he said "some countries" are considering introducing rules that will allow entry only to people who have been vaccinated.
He said the government is working with other countries to develop how such certification can work.
"We want Brits to be able to travel to those countries and therefore enable Brits to be able to demonstrate their vaccine status, so that sort of vaccine certification is something we are talking to our international counterparts about and there are people who are arguing that is the right way to have safe global travel again because obviously that’s very restricted at the moment," he told Sky News.
One country already moving ahead with such a scheme is Israel, which is planning to restart some tourism as part of a gradual return to normality.
Last week, the country – where more than 41% of people have received at least one shot of a vaccine – signed a deal with Greece to ease travel restrictions for Israelis with a "Green Pass" proof of vaccination.
On Sunday, foreign secretary Dominic Raab said domestic COVID vaccine passports, used to move around within the UK, hadn't been ruled out and are "under consideration, but of course you've got to make it workable".
He added: "I'm not sure there's a foolproof answer in the way that it's sometimes presented but of course we'll look at all the options."
Meanwhile, the World Health Organization's special envoy for the global COVID response said he expects vaccine passports will be brought in.
Dr David Nabarro told Sky News: "I am absolutely certain in the next few months we will get a lot of movement... so some sort of vaccine certificate no doubt will be important."
The UK hit its target of offering a vaccine to the roughly 15 million people in the top four priority groups on Sunday, ahead of its 15 February deadline.
Watch: What you can and can't do in lockdown