The reproduction number, or R value, of coronavirus transmission across the UK is between 0.8 and 1, the Government Office for Science and the Scientific Advisory Group for Emergencies (Sage) said.
Last week, it was between 1.2 and 1.3.
R represents the average number of people each Covid-positive person goes on to infect.
When the figure is above 1, it means the outbreak is growing exponentially.
An R number between 0.8 and 1 means that, on average, every 10 people infected will infect between 8 and 10 other people.
The estimates for R and the growth rate are provided by the Scientific Pandemic Influenza Group on Modelling (Spi-M), a sub-group of Sage.
The growth rate, which estimates how quickly the number of infections is changing day by day, is between minus 4% and minus 1% for the UK as a whole.
It means the number of new infections is shrinking by between 1% and 4% every day.
Scientists advising the Government said that all regions of England have seen decreases in the R number and growth rate estimates compared with last week, and R is below or around 1 in every region.
However, they warned that despite the reductions, case levels “remain dangerously high and we must remain vigilant to keep this virus under control, to protect the NHS and save lives”.
Sage scientists said: “It is essential that everyone continues to stay at home, whether they have had the vaccine or not.
“We all need to play our part, and if everyone continues to follow the rules, we can expect to drive down the R number across the country.”
