THE coronavirus R rate stays below 1 across UK - but "vast majority susceptible to infection", the Government's top scientist has warned.
Sir Patrick Vallance said that the value had now fallen in every part of the country and is between 0.7 and 0.9.
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But he cautioned that about six to seven per cent of the population is thought to have been infected with Covid-19 - meaning "a vast majority of the population remain susceptible".
Referring to data from the Office for National Statistics, he said 53,000 were thought to be infected between May 17 and 30.
Speaking at the daily Downing Street press conference, he said: "The R is below one, but perhaps only just below one.
"The epidemic is shrinking, but not fast. Numbers are coming down but are not yet very low.
"The vast majority of the population remains susceptible to the infection.
"That urges caution, it urges going slowly with changes and it urges measuring very carefully to see the impact and being prepared to reverse things where measures have been taken that have an impact on this, and importantly means looking for outbreaks locally and dealing with those fast."
The R-number is the average number of people that will contract coronavirus from an infected person.
If R is one or higher, the virus will spread exponentially through the population.
Researchers had warned the vital number was above one in the North West of England and firmly at 1 in the South West last week.
But earlier this week, Health Secretary Matt Hancock told ministers that R value had fallen - and the virus is "in retreat".
Support bubbles
It comes as Boris Johnson announced that couples kept apart by lockdown restrictions could be reunited and some grandparents will be able to hug their grandchildren from Saturday.
The latest move to ease England's coronavirus lockdown will allow adults living alone or single parents to form a "support bubble" with one other household.
They would then be allowed to mix as though they were one household, spending time together indoors, not having to follow the two-metre rule and would be allowed to stay overnight.
Ministers believe the latest easing of the lockdown will help those who have been left isolated while still restricting the spread of coronavirus.
The move could allow children in single-parent households to see one set of grandparents.
A grandparent living alone would be allowed to visit the house of their child and grandchildren.
But the move would not allow a couple to visit both parents as neither household would comprise a single adult.
Officials admitted the measure was not going to benefit everyone but was targeted at those who had been left isolated by the lockdown restrictions.
At the Downing Street briefing, the Prime Minister said: "We are making this change to support those who are particularly lonely as a result of lockdown measures.
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"It's a targeted intervention to limit the most harmful effects of the current social restrictions.
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"It is emphatically not designed for people who don't qualify to start meeting inside other people's homes, because that remains against the law."
Meanwhile the number of deaths involving Covid-19 in the UK has passed 52,000, according to analysis of the latest available data.