The R rate for coronavirus in the south west is the highest in England - but health chiefs in Dorset have highlighted to low number of cases in the county.

The reproduction number, referred to as R, for the virus has been published at regional level in England for the first time by the Scientific Advisory Group for Emergencies (Sage).

Across England, the value is 0.8-1.0, with the figure at 0.8-1.1 for the south west, although experts gave a warning about regional analysis.

The R value is the average number of people an infected person passes the disease on to and if that figure exceeds one, the disease could rapidly spread throughout the population again. This is why the government is attempting to keep it below one.

Swanage and Wareham Voice: Coronavirus testing laboratory

Sam Crowe, director of Public Health for Dorset and BCP Councils, said: “Whilst the government uses the R rate to set the alert level for the country, locally we consider more measures than just the R rate when monitoring the situation in Dorset.

"One of the key things to look at is the number of cases, and I’d like to reassure residents that in Dorset the number of cases has been and still is a lot lower than in other parts of the country.

"Out of 150 upper tier local authorities in England, Dorset Council currently has the second lowest case rate per 100,000 of the population, and BCP Council has the seventh lowest. It’s important not to look at the R rate alone.

Swanage and Wareham Voice:
"It’s not possible to calculate an accurate R rate at a very local level. Regional figures for the R rate relate to the whole of the South West not just Dorset. As we’ve got low numbers of cases in the South West, any change can make a disproportionate difference in the R rate.

"Working with councils and other partners, we are developing local outbreak management plans so we can respond to any potential increases in cases in Dorset in the future.

"It's also important that all residents continue to take responsibility, respect the restrictions around social distancing, and practice good hygiene by regularly washing hands. This is the best way for everyone to protect themselves and their loved ones. And I’d like to remind anyone who has symptoms to get tested and use the Test and Trace system to identify anyone they’ve had close contact with.”

Swanage and Wareham Voice:

Experts say R is not the only important measure of the epidemic and it indicates whether the epidemic is trending towards getting bigger or smaller but not how large it is.

Therefore, the number of people currently infected with Covid-19 – and so able to pass it on – is very important.

R should always be considered alongside the number of people currently infected.

As an average value, R can vary in different parts of the country, communities and subsections of the population.

It cannot be measured directly so there is always some uncertainty around its exact value.

When there are a small number of cases, estimates of R become less robust and less useful in determining the state of the epidemic.

The R values are shown as the range and the most likely estimate is in the middle of this range.

Last week, Public Health England and Cambridge University’s MRC Biostatistics Unit published estimates of the Covid-19 R value at a regional level across England.

However, to avoid confusion, it will no longer be doing this as it feeds into the consensus of the R value published by Sage.