Boris Johnson has said "there is going to be a role" for COVID vaccine certification but suggested it might only be implemented once every adult in the UK has been offered a vaccine by the end of July.
The prime minister sought to quell anger from Conservative MPs and businesses over the possibility of Britons being asked to show proof of having had a coronavirus vaccine – or a negative test result – before entering a pub.
Speaking on a visit to a nursery in west London on Thursday, Mr Johnson insisted "no decisions have been taken at all" ahead of the results of a government review into COVID certification being made public early next month.
The prime minister said "all sorts of things are being considered", but added it was "a bit premature" to speculate on whether pubs could ditch social distancing and mask-wearing requirements entirely by implementing a certification scheme.
"What we want to do is rollout the vaccine programme and see what that builds in terms of general resistance to the virus," he said, as he was quizzed about what has been dubbed a "papers for the pub" scheme.
"I do think there is going to be a role for certification."
Pressed on when the public will be told the results of the government’s review of COVID certification, Mr Johnson added: "What we’ve said is we’ll be reporting on the work of the certification group in early April, either on 5 April or 12 April."
"We need to think carefully about the issues. As I’ve said before there’s lots of difficult issues, because there are some people who, for medical reasons, can’t get a vaccination, pregnant women can’t get a vaccination at the moment," the prime minister said.
"You’ve got to be careful about how you do this. You might only be able to implement a thoroughgoing vaccination passport scheme – even if you wanted such a thing – in the context of when absolutely everybody had been offered a vaccine."
Mr Johnson suggested whether someone had had a vaccine, someone’s possible immunity after having recovered from the virus, or a negative test "could work together" in a possible certification scheme.
But he stressed the initial reopening of pubs and restaurants on 12 April, when customers can be served outdoors only, would be "unaffected" by any COVID certification plans.
The prime minister made the suggestion of using COVID certification for pubs in an appearance before a group of senior MPs on Wednesday.
Businesses and some Conservative MPs reacted with anger at the plans, with it highlighted how government ministers had previously rejected the prospect of "vaccine passports" within the UK.
Emma McClarking, the chief executive of the Beer and Pub Association, told Sky News’s Ian King Live the government risked placing "an unnecessary burden on businesses that are already struggling".
"When we get our doors open again we will be doing everything we can to create that COVID-secure environment – we’ve invested millions to do so," she said.
"But this would really be an unnecessary responsibility to burden our businesses at a time when they’re desperately trying to recover."
She added ministers were "supposed to be focusing on removing all restrictions by 21 June, not adding in more".
Conservative MP Mark Harper, the chair of the COVID Recovery Group of Tory backbenchers, told Sky News: "I actually agree with the prime minister – that is the prime minister of February when he said he didn’t think there was a case for expecting people to show papers to go to the pub.
"And he said there were very significant problems with ethical, moral questions about this issue.
"I’ve heard some heads of pub chains this morning set out some of those significant problems."
Meanwhile, Labour’s shadow business secretary Ed Miliband accused the prime minister of making COVID policy "on the hoof".
"There are big questions about whether this should really be left to landlords to make the decision," he told Sky News.
"What about pregnant women and others, who are not necessarily getting the vaccine?
"What about young people to whom the vaccine won’t have been rolled out yet?
"There are big questions. We’ve got to follow the science and if this is what the science demands, we will look sympathetically at it.
"But I think the government have got a lot of questions they’ve got to answer about this policy."