Allowing people who have had both doses of the coronavirus vaccine to meet up with each other without social distancing has been ruled out.
During the government's daily coronavirus briefing, the prime minister and England's chief medical officer, Chris Whitty, said it remained too risky for such a prospect.
A member of the public asked why people who have had both jabs couldn't socialise "exclusively" with one another, while Sky's Sam Coates questioned if it was time to apply "common sense" to elderly people who have been fully vaccinated.
More than 10 million people in the UK have had a first dose and nearly half a million their second - figures that are growing by the day - but Boris Johnson said it was still too soon to relax measures.
The prime minister said further down the line the government may think about "what potential is opened up by these vaccinations".
However, he added that there wasn't yet enough data on the potential of vaccinated people to catch and transmit the virus, despite being vaccinated themselves.
If people are out more - even if they are meeting others who are vaccinated - they might still be able to spread the virus.
There are some encouraging signs though.
A study on the AstraZeneca/Oxford vaccine has shown a significant reduction in positive swabs in vaccinated people, meaning there are fewer with asymptomatic infections who could pass the virus on.
But Professor Whitty said the scientific community was still "not absolutely confident about exactly how much" the vaccines reduced transmission.
He was unequivocal that there could be no exemptions to lockdown rules at the moment.
"[The] really clear advice at the moment is please stick to social distancing irrespective of whether you've had vaccination."
He said it was also vital that over-70s remember that the vaccine does not have an immediate effect, that it "takes two to three weeks - in older people probably slightly longer - to achieve any kind of protection".
Prof Whitty said the UK is "nowhere near" having a low enough infection rate to consider exempting a certain group from COVID rules or loosening lockdown.
He called the current infection rate of around 1 in 55 people still "incredibly high", and that the vaccine plus social distancing was the key to "pull the rates of the virus right down".
"And then if you've got very low community [infection rates], you're vaccinated and your friends and colleagues are vaccinated, that will substantially reduce the risk for everybody," he said.
There are further signs of encouragement as well, as England's chief medical officer added that it appeared the country was through the peak of the second wave.
Latest official figures show the UK has recorded another 1,322 deaths within 28 days of a positive coronavirus test, as well as a further 19,202 new cases - a third of what was recorded towards the start of January.