Latest R number in south west 'most likely' above one

However, the government has warned the actual figure is likely to be higher, due to the delay in between someone being infected and needing healthcare - and indeed, scientists at Cambridge University that use real-time tracking of Covid-19 stated yesterday: "We estimate it is very likely that R is close to one in most regions of England.

"The South West is the region in which it is most likely that R is above one, with a probability of 60 per cent, although the number of new infections is very low."

In the official updated data on the government website today though it states that the current rate of reproduction - known as the R number - in the south west is now at between 0.8 and 1.1.

It means that for every one person with the infection a further 0.8 to 1.1 people are likely to go on to be infected - and marks no change on last week's estimates.

Certain figures, including for the south west, come with a warning however, stating: "Low case numbers and/ or a high degree of variability in transmission across the region means these estimates are insufficiently robust to inform policy decisions."

The website goes on to state that with the values shown as a range, the most likely true values are somewhere towards the middle.

And it adds: "When there is a significant amount of variability across a region, for example due to a local outbreak, then a single average value does not accurately reflect the way infections are changing throughout the region.

"It is more appropriate to identify local hotspots through, for example, monitoring numbers of cases, hospitalisations, and deaths."

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Nationally the latest R number range for the UK is set at between 0.8 and 1.0, with a growth rate of zero per cent and minus five per cent.

The website goes on to state: "A growth rate between zero per cent to minus five per cent means the number of new infections is somewhere between remaining stable and shrinking by five per cent every day."

It adds the data should be regarded as a guide to the general trend rather than a description of the epidemic state.

And it warns the estimates represent the transmission of Covid-19 from several weeks ago, due to a time delay between someone being infected and needing healthcare. Estimates that use "more timely data" reflecting infections suggest a higher R for England, it added, saying: "As a result, SAGE (the Scientific Advisory Group for Emergencies) does not have confidence that R is currently below one in England."

In the latest modelling by the MRC Biostatistics Unit at Cambridge University, published yesterday on August 6, the south west region was putting at having an average median R number of 1.03, with 0.74 at the lowest end and 1.33 at the highest. This is based on real-time tracking of Covid-19.

It put the south west as the region with the highest rate in the country again in their figures.

A graph showing the south west R number plotted over the months since March. Image: MRC Biostatistics Unit at Cambridge University

However the scientists go on to warn: "In the regions where the central estimate for R is greater than or equal to one, the estimation is uncertain and the number of daily new infections is low.

"These two factors combined indicate that there is no particular public health concern for any of these regions, though the situation should be monitored closely."

They added that their current estimate of the average number of infections arising each day across England is 3,200 (between 1,700 and 5,800) and they predict that the number of deaths each day is likely to be between 47 and 91 by the end of the third week of August.

The Cambridge model is only one of the models that feeds into the official regional R rate estimate by SAGE though.

And government advisers have always stressed that regional R numbers should be viewed with caution, because as the number of infections falls the values become less reliable.

GOVERNMENT FIGURES

Region R Growth rate % per day

England 0.8-1.0 -3 to 0

East of England* 0.7-0.9 -4 to -1

London* 0.8-1.1 -4 to +1

Midlands* 0.8-1.0 -3 to 0

North East and Yorkshire* 0.8-1.0 -4 to 0

North West 0.8-1.1 -3 to +1

South East 0.8-1.0 -4 to 0

South West* 0.8-1.1 -3 to +3

*Low case numbers and/ or a high degree of variability in transmission across the region means these estimates are insufficiently robust to inform policy decisions.