The reproduction rate of coronavirus (R number) may have tipped above 1.0 in London, the North West and South West regions of England, meaning the spread of the virus could now be increasing rather than decreasing.
The numbers suggest there is a risk that the overall coronavirus epidemic in the UK is growing, Government scientists say.
Sage - the government's Scientific Advisory Group for Emergencies - says it "does not have confidence that R is currently below 1 in England" because of a delay in data the group uses to make estimates.
Regional R numbers
England - 0.9-1.0
East of England - 0.8-1.0
London - 0.9-1.1
Midlands - 0.8-1.0
North East and Yorkshire - 0.8-1.0
North West - 0.9-1.1
South East - 0.8-1.0
South West - 0.8-1.1
An R number below 1.0 is crucial for scientists to have confidence that the prevalence of coronavirus is going down in Britain.
If the number is above 1.0 it means each person with the virus will pass it on to more than 1.0 person.
For example, if the number is 1.1, it means each person with coronavirus is passing it to 1.1 people.
When the UK was under full national lockdown, ministers said the R number needed to be consistently below 1.0 before restrictions could be lifted.
ITV News Health Editor Emily Morgan explains why local lockdowns are so important as the reproductive rate of coronavirus continues to increase across the UK
A local lockdown has already been placed on large parts of the North West and the estimated R number in the South West and London will be a cause of concern for local officials hoping to avoid new restrictions.
The latest growth rate for the whole of the UK is between minus 3% to plus 1%, a slight change from between minus 4% to minus 1% last week.
The growth rate of coronavirus transmission reflects how quickly the number of infections is changing day by day.
Regional growth rates
England -3 to 0
East of England -3 to 0
London -2 to +1
Midlands -4 to 0
North East and Yorkshire -4 to 0
North West -2 to +1
South East -4 to 0
South West -1 to +2