The latest numbers suggest that easing lockdown measures in England – with the reopening of pubs, restaurants and hotels on 4 July – has not affected the infection rate so far. However, a rise in infections may be slower to emerge due to a lower prevalence of the virus in society.
Experts on the government’s Scientific Advisory Group for Emergencies (Sage) consider the R number a vitally important measure in tracking the spread of the virus.
They have said the government’s goal should be to keep the value below one, leading to a fall in the number of coronavirus cases and deaths.
If the R value is one, each person infected with the virus passes it on to one other person, meaning the prevalence of the virus in society will remain at the same level.
The reproduction number showing the rate of coronavirus infection in England has remained at a similar figure to last week, new figures show, with no discernable spike following the reopening of pubs and restaurants.
The growth rate is now at -4 to -1 per cent per day, compared with a rate of -5 to -1 per cent per day last week, the government revealed on Friday.
The reproduction rate, referred to as R, remains between 0.7 and 0.9 across the UK, according to figures published by the Government Office for Science and the Scientific Advisory Group for Emergencies (Sage).
Government officials and advisers have said it is important to recognise while the values are shown as a range, the true figure is likely to be somewhere towards the middle of this range.
However, if the value is two, each person carrying the virus transmits it to two people, leading to exponential spread.
If the value falls below one, the prevalence of the virus in society begins to diminish over time.
Put simply, if the R value is greater than one the epidemic is growing, while if it is less than one it is shrinking.
However, there was some regional variation between the figures released on Friday.
In the east of England, the growth rate increased from -5 to 1 per cent per day last week, to -3 to 2 per cent per day. The R number is 0.8-1.0.
In London, the growth rate is between -5 and 1 per cent, compared to between -3 and 2 per cent last week. The capital has an R value of 0.8-1.0.
The Midlands has a growth rate of -5 per cent to zero, compared to -5 to minus -1 per cent last week. Its R value is 0.7-1.0.
In the northeast and Yorkshire, the growth rate is between -4 per cent to zero, up from between -5 to -1 per cent last week. Its R number is 0.8-1.0.
The northwest has a growth rate of -5 to -1 per cent, a change from -6 to -1 per cent, and an R value of 0.7-1.0.
The growth rate in the southeast is at -3 to 1 per cent, compared with -4 per cent to zero last week. The R value in the region is 0.8-1.0.
In the southwest, the growth rate changed from between -6 and 2 per cent last week to between -5 and 2 per cent. Its R value is 0.7-1.0.
Across England however, the growth rate remains unchanged at between -4 per cent and zero, while the R value is 0.8-1.0.
The Government Office for Science and Sage say in some regions the low case numbers and/or a high degree of variability in transmission across the region means the estimates are insufficiently robust to inform policy decisions.
Separate figures released by the Office for National Statistics showed an estimated 27,700 people were infected by coronavirus in the community, outside hospitals and care homes, in the week ending 19 July, an increase of 1,100 on last week’s numbers.
Last month, Sir Patrick Vallance, England’s chief scientific adviser, said the country was approaching the point where the R number would no longer be a useful measure for reproduction as the smaller number of cases would mean local outbreaks could give a skewed impression.
Epidemiologists have also stressed that estimates of R, which rely on predicting human behaviour as well as the ability of a virus to transmit, are imperfect and are constantly under revision.
In March, the World Health Organisation said the coronavirus had a R value between 2 and 2.5, in a population with no immunity or social distancing measures.