Number of people estimated to be infected with Covid-19 dramatically revised down, First Minister confirms
Scotland’s estimated number of people infected by Covid-19 has been revised down by more than half.
The revision hinges on the assessment of the critically important figure put on the rate at which an infected person transmits the virus to others, the so-called R-number.
If it was two, for example, then for each carrier two new people would be infected. Currently the estimate is between 0.6 and 0.8.
First Minister Nicola Sturgeon said today that this is a positive development and meant the figures continued to move in the right direction. It had earlier been estimated between 0.7 and 0.9 but she warned that was high enough to allow the virus spike exponentially again.
She also revealed that the current estimate for the number of people carrying the virus in Scotland is 4500 – previously it had been thought that it was 11,500.
She said: “The R-number shows the rate at which this virus is reproducing so if the R-number is as above one then every person with the virus will infect more than one other person and the virus when spread exponentially but if the R-number is below one then the number of people with the virus will fall.
“We estimate the R-number in Scotland, as of last Friday June 5, was between 0.6 and 0.8 – that is a lower estimate than for two weeks ago when we calculated that the number was likely to be between 0.7 and 0.9 so under that estimate we expect that the virus will continue to decline.
“In addition, we estimated last Friday that 4500 people in Scotland had the virus and were infectious – our previous estimate for May 29 was that 11,500 people were likely to be infectious.
“Now that of course sounds like a very big decline, so it's worth stressing that we don't actually think the number of infectious people has more than halved in just one week but just what has been happening is that we have been reassessing our estimates for previous weeks based on the latest figures available to us.
“In short it is likely that the 11,500 was an over-estimate not that the number has halved in a single week. These latest estimates reflect the encouraging data that we have seen in the last couple of weeks and there is no doubt looking at all of this data that we're making very real progress in combating and suppressing the virus.
“As always it's important that I inject a note of caution firstly at the estimates that I have reported to you today. Of course we don't yet take account of the phase one changes and as we need the easing of the lockdown we need to continue to monitor any impact from that carefully.
“And secondly the number of people who we estimate infectious is certainly smaller than it was but it is also still large enough to make the virus take off rapidly again if the R-number was to go much above one so we need to celebrate the progress but continue to be careful and cautious.
“A week today we will have a further review of the lockdown restrictions, I am currently very hopeful that at that point we will be able to lift some further restrictions, we may not be able to do everything in phase two but I hope we can do at least some of that.
An announcement on a further easing of lockdown measures is expected this time next week. Ms Sturgeon cautioned against complacency and has previously said decisions will be based on available data and evidence.
Related: Could coronavirus lockdown be eased more quickly in the Highlands?