R number value for UK coronavirus transmission may still be above one

Credit: PA

The reproduction number, or R value, of coronavirus transmission across the UK may still be above one.

Data released on Friday by the Government Office for Science and the Scientific Advisory Group for Emergencies (Sage) shows the estimate for R across the UK is between 0.9 and 1.1.

The growth rate of coronavirus transmission, which reflects how quickly the number of infections is changing day by day, has increased slightly.

What is the R value and why is the number one so important in stopping the spread of coronavirus?

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 - 0.8-1.0

  • 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.

Credit: Andrew Milligan/PA

In England, the R is between 0.9 and one, and the growth rate is minus 2% to plus 1%.

For the whole of the UK, the latest growth rate is between minus 1% and plus 2% per day, a slight change from between minus 2% and plus 1% last week.

The growth rate means the number of new infections is somewhere between shrinking by 1% and growing by 2% every day.

Regional growth rates

  • England -2 to +1

  • East of England -5 to 0

  • London -3 to +2

  • Midlands -6 to 0

  • North East and Yorkshire -3 to 0

  • North West -3 to 0

  • South East -4 to 1

  • South West -4 to +1

The most likely value is towards the middle of the range, experts advising the government say.

The R number represents the number of people each Covid-19 positive person goes on to infect.

But the experts say the numbers should be interpreted with caution.

This is because when case levels are low, there is a high degree of variability in transmission and a single average value may not accurately reflect the way infections are changing throughout the region.

Local outbreaks, for example, can skew the numbers, even though overall transmission may be low across the region.

Scientists say that, when disease incidence is low, or there is a high degree of variability in regional transmission, the estimates of R and the growth rate "should not be treated as robust enough to inform policy decisions alone".

It is more appropriate to identify local hotspots through, for example, monitoring numbers of cases, hospital admissions, and deaths, the team behind the data said.