Expert comments about ‘R’, the reproduction number of the coronavirus

Some comments on the reproduction number of the virus (“R” or “R₀“) after the figure was mentioned in the Government’s daily press conference earlier this evening.

Dr Robin Thompson, Junior Research Fellow in Mathematical Epidemiology, University of Oxford, said:

“The reproduction number, or “R”, represents the number of individuals that a typical infectious person is likely to go on and infect.  The value of R changes during an outbreak in response to public health measures, and is currently below one.  However, if current measures are relaxed, the contact rate between individuals will increase, potentially leading to more infections.  As a result, there would be a danger that the reproduction number increases back above one and we see a second wave of infection, as well as a second peak.

“A key challenge now for epidemiologists is to identify measures that can be relaxed that have only limited impacts on the value of R.  One of the reasons that this is particularly challenging is that interventions were first introduced in the UK within a few days of each other.  As a result, it is hard to disentangle the relative effects of different interventions on the reproduction number.”

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