Coronavirus has changed everything. Make sense of it all with the Waugh Zone, our evening politics briefing. Sign up now.
Latest estimates suggest the UK-wide reproduction rate of coronavirus – the so-called “R rate” – has remained at 0.7 to 1.0 for a second week.
Boris Johnson has said driving the R down is key to any further easing of the lockdown measures.
There is a time lag in the calculations, with the government scientists’ latest R value relating to what was happening two to three weeks ago.
If R is greater than 1 the epidemic is generally seen to be growing; if R is less than 1 the epidemic is shrinking.
R measures the number of people, on average, that each sick person will infect.
An R number of 1 means that on average every person who is infected will infect 1 other person, meaning the total number of new infections is stable.
If R is 2, on average, each infected person infects two more people.
If R is 0.5 then on average for every two infected people, there will be only one new infection.
At the start of March the World Health Organisation (WHO) estimated the R in the UK was between 2 and 2.5.
There are also thought to be significant regional variations in the spread of the virus.
A model from Public Health England and the University of Cambridge’s MRC Biostatistics Unit last week suggested the R rate in London was just 0.4 while in the North East and Yorkshire it was 0.8.
Yesterday Matt Hancock, the health secretary, announced a government study suggested around one in six people in London and one in 20 elsewhere in England have already had the virus.
And No.10 today did not rule out allowing the capital to emerge from the coronavirus lockdown before other parts of the country.
It came after a leading mathematical modeller claimed putting the UK into lockdown just one week earlier would have had a “dramatic” impact on the number of deaths caused by the pandemic.
Writing for HuffPost UK, Kit Yates, co-director of Bath University’s centre for mathematical biology, said that speedier intervention could have saved thousands of lives, while making it easier to reopen the economy and protect the NHS at the same time.
Yates underlined a new analysis by climatologist James Annan that estimated three quarters of the UK’s fatalities – at least 27,000 deaths – may have been avoided with a lockdown imposed seven days earlier than March 23, when Johnson finally opted to do so.
This article originally appeared on HuffPost.