Brits who have received two doses of a coronavirus vaccine could avoid a 10-day quarantine if they come into contact with someone who tested positive for the virus.
Under new proposals, people could choose to take a test every morning for a week instead of self-isolating when contacted by NHS Test and Trace.
A negative result would give people 24 hours of freedom before another test is needed.
The plans could be introduced in the hope that fully jabbed people can return to their normal life, without quarantining.
Health Secretary Matt Hancock is said to be considering the idea of replacing self-isolation with daily Covid tests.
A Whitehall source told The Times : "The vaccines are extremely effective and we want to keep people safe whilst minimising interruption to their lives.
"So of course it is an attractive option if shown to be safe."
An ongoing study of 40,000 is due to finish by the end of summer and, if the results are satisfactory, Chief Medical Officer Chris Whitty could approve the new plans.
Another source said: "It’s obviously very appealing if it’s safe so we need to show that before we bring it in."
Professor Adam Finn, who advises the Government on the Joint Committee on Vaccination and Immunisation (JCVI), described the idea as an "interesting" proposal.
He told Times Radio: "We know that the vaccine, particularly after two doses, is highly effective at stopping you from getting seriously ill, 20 times less likely to end up in hospital.
"We also know that it will reduce your chances of getting milder illness and infecting other people, but it's probably less good at doing that than it is preventing you getting seriously ill, so it's a kind of balance of risk thing."
Asked if it would be safer to properly support people as they self-isolate rather than reduce the quarantine time, he said: "Yeah, difficult calculation, because I think in practice, for whatever reason that doesn't happen reliably, so that people are being penalised by self-isolating and that probably results in some people not self-isolating and others suffering financial hardship as a result.
"This is one way to avoid that, and presumably at somewhat lower risk than just letting everybody circulate when they potentially may have been exposed."
He added a "third wave" of coronavirus infections "is definitely under way".
The University of Bristol academic told BBC Radio 4's Today programme: "It's going up, perhaps we can be a little bit optimistic it's not going up any faster, but nevertheless it's going up, so this third wave is definitely under way.
"We can conclude that the race is firmly on between the vaccine programme, particularly getting older people's second doses done, and the Delta variant third wave."
Figures released yesterday showed that the Delta variant of Covid-19 is now responsible for 99 per cent of cases in the UK.
Infections involving the strain first identified in India rocketed by 79 per cent in a week with 33,630 new cases in just seven days, taking the total to 75,953.
England’s R rate, which reveals how quickly the virus is spreading, remained unchanged from last week at 1.2 to 1.4, meaning that the disease is growing exponentially.
Of the 75,953 Delta cases, 70,856 were in England, 4,659 in Scotland, 254 in Northern Ireland and 184 in Wales.
