People who test positive for coronavirus antibodies will be given "immunity certificates" to allow them to leave lockdown and return to normal life, health secretary Matt Hancock has announced.
The move, already planned in Germany, will be implemented if hoped-for antibody tests – showing a person was infected, but is now healthy – become available on a mass scale.
Mr Hancock cautioned that the antibody tests may not be introduced for some time, as none has yet obtained approval from Public Health England by meeting required accuracy levels.
Asked if the German model would be adopted, he told a 10 Downing Street press conference: "We are looking at an immunity certificate - how people hwo have had the disease, have got the antibodies and therefore have immunity can show that and so get back as much as posislbe to normal life.
"That is an important thing that we will be doing and are looking at, but it's too early in the science to be able to put clarity around that."
Mr Hancock's announcement came after Boris Johnson's official spokesman told reporters that the UK was ready to "consider" the use of certificates if they proved useful in other countries.
Researchers in Germany are already exploring how the authorities will be able to eventually issue passes to exclude essential workers from the harsh crackdown currently in place.
In the UK, ministers see the antibody test as the “potential game-changer” – and have ordered millions, but they have yet to pass regulatory tests.
Professor John Newton, of Public Health England said that once an antibody test is approved, it can be "scaled very quickly to a very large number of people - millions and millions of people".
He stressed that it was not yet known whether the antibodies will indicate permanent immunity from coronavirus, or only short-lived protection from a return of the disease.
"I think we have to be optimistic that it will give some immunity, but we're just not quite sure how much at the moment," he said.
People who test positive for coronavirus antibodies should no longer be infectious themselves and would have at least some immunity, scientists believe, based on what is known about common colds.
The idea was unveiled as Mr Johnson prepared to stay in isolation longer than he hoped after appearing poorly in a video message from his Downing Street flat.
The prime minister was due to go back to his office on Friday – seven days after being diagnosed with coronavirus – but still had symptoms, No 10 acknowledged.
Asked if he would leave isolation on Friday, his spokesman repeatedly refused to give a guarantee, saying only: “We will follow the guidelines ... you can rest assured on that.”
Meanwhile, Downing Street made its clearest admission yet that it is falling badly short on testing if someone currently has the virus, promising a “significant increase” would be announced later today.
“We acknowledge that more needs to be done,” the spokesman told journalists. “We agree we need to be testing more people and to make progress very quickly.”
However, he argued the much-criticised figure that just 2,000 NHS staff had been tested – clearing them to return to the frontline, if negative – was an underestimation.
It said 2,800 had now been seen at drive-in testing facilities, plus an unspecified “significant number” at NHS and Public Health England laboratories.
The spokesman also rebuffed calls to reduce the five-week wait for universal credit, to help a deluge of applicants, saying: “People can take an advance if they need money urgently.”
And he refused to confirm or deny whether mobile phone location data is being used to decide on the success or otherwise of the lockdown.
“We’ve received data from a wide variety of sources in relation to protecting people’s health, but at all times we follow data protection rules,” he insisted.
