The Scotsman

Covid-19 numbers


At the First Minister’s Covid-19 press conference on 7 May (“Pennington says no evidence easing lockdown will spark second spike”, The Scotsman, 8 May), she said that she had no idea on what I was basing my comments on the “R” number in care homes.

In my evidence to the Scottish Parliament Health and Sport Committee on 28 April I said that the “R” number in some might be as high as ten or even higher, and said that these estimates were based on the number of cases in them.

The calculatio­n is simple: “R” is the number of secondary infections produced when one infected individual is introduced into a population where everyone is susceptibl­e.

It is reasonable to assume that at present all care home residents and staff are susceptibl­e. So if a care home has ten cases that fell ill at about the same time resulting from the virus being brought in by one person, the “R” number is ten.

Many Scottish care homes have had many more than ten cases. Sadly, some have had more than ten deaths; even for the elderly with underlying health conditions the Covid-19 mortality rate is less than 100 per cent so the infection rate will almost certainly be significan­tly greater than the number of deaths.

For the avoidance of any doubt regarding my expertise, I have worked with and handled in the laboratory many viruses spread in the same way as Covid-19 including

smallpox, measles, Newcastle disease, pseudorabi­es and influenza, advised the government on infection prevention including those in care homes, and published a peerreview­ed paper on recording antibody reactions jointly with June D. Almeida at the time when her research was leading to the discovery of human coronaviru­ses and the invention of their appellatio­n. HUGH PENNINGTON Carlton Place, Aberdeen

In her Comment article (9 May), Jane Bradley says that she was hugely relieved by the negative coronaviru­s test on her daughter “not least (because) we would not have to go back for another test”.

I assume she meant that she was relieved there would be no need to go back for another test immediatel­y, as a negative test today unfortunat­ely does not mean that one will not be infected by the virus tomorrow, next week or next month.

K. W. MCKAY Easter Duthil, Carrbridge

“Accept tougher rules to save lives, Scots told” (The Scotsman, 9 May). Told? What happened to the grown-up conversati­on?

What Scots are being asked to accept is greater social and economic problems just so the SNP Government can be different from the English. But then, that is the SNP’S mission, pandemic or not.

(DR) S. J. CLARK Easter Road, Edinburgh

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