The UK's coronavirus reproduction number - known as R - is between 0.7 and 1.1, according to the latest estimate.
The R refers to the number of people an infected person will pass COVID-19 on to.
It means that, on average, every 10 people infected will infect between 7 and 11 other people.
Last week it was between 0.8 and 1, the Science and the Scientific Advisory Group for Emergencies (SAGE) said.
The greater range is thought to be down to regional variations in the number.
The latest growth rate range is between -5% and 0%, meaning that the number of new infections is broadly flat or shrinking by up to 5% every day.