The Government Office for Science published the latest estimates of the number as between 0.7 and 1.0, which reflect the state of transmission a fortnight ago. Last week, Prime Minister Boris Johnson said that the number was between 0.5 and 0.9.
The R value or reproduction number, is used to rate a disease’s ability to spread based on an average number of people that one infected individual will pass the virus on to.
A value higher than 1 means that the number of cases will start to rise again.
On Friday, Jenny Harries, a deputy chief medical officer for England, announced the new calculations at the Downing Street briefing.
She said: “If it goes above that number we will start to see an increasing number of cases and we may experience the second peak, so it’s important that we keep monitoring it.”
The latest figures curated by the scientific advisory group for emergencies, Sage, were calculated based on hospital admissions and deaths, among other sources.
However, the R value contains a time lag due to the nature of the data collection as the events, such as death, take place several weeks after infection.
Consequently, the latest calculations reflect infection rates at least a week before Mr Johnson eased some lockdown restrictions.
The chief executive of the NHS, Sir Simon Stevens, told the Daily Mail that hospital admissions for the virus have halved since the peak of the pandemic last month.
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Keith Neal, emeritus professor in the epidemiology of infectious diseases at Nottingham University, told the Times that if a large chunk of Britain’s transmission were in care homes then a different response from the social distancing measures enforced outside would be required.
Speaking to the Times he said: “If the R is being pushed up by care homes this is not an issue for community transmission.
“Care homes need to be controlled by infection control.
“The R in care homes does not influence your control measures in these circumstances.”
Mr Neal added that within care homes the R value was “totally irrelevant” and was only applicable when the outbreak escaped into the wider community.
Dr Harries agreed that focusing on the R could obscure nuance when answering questions at Downing Street on Friday.
She said: “It’s a really important measure, but the real outcome that we’re looking for is a reduction in the number of cases and getting rid of the epidemic in the UK.”