The estimated R rate for coronavirus across the UK has dropped to between 0.8 and 1, according to the latest official figures.
It was estimated to be between 0.9 and 1 last week.
The R number represents the average number of people each Covid-19 positive person goes on to infect.
When the figure is above 1, an outbreak can grow exponentially.
Visit our live blog for the latest updates Coronavirus news live
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 3% and minus 1% for the UK as a whole.
It means the number of new infections is shrinking by between 1% and 3% every day.
Estimates for R and growth rates are shown as a range and the true values are likely to lie within this range, according to the experts.
Separate figures released earlier by the Office for National Statistics show that the number of new Covid-19 infections in England is continuing to fall.
The data suggests that the incidence rate is now at its lowest since the end of September.
It comes just days before the rollout of the first batch of coronavirus vaccine developed by Pfizer/BioNTech.
Chris Hopson, chief executive of NHS Providers, said the first doses of the vaccine will be administered on Tuesday.
He said it will be ‘a marathon, it’s not a sprint’, telling BBC Breakfast: ‘We’re looking forward to the race starting on Tuesday.’
Get in touch with our news team by emailing us at [email protected]
For more stories like this, check our news page.