FabSwingers.com forum: The 'R' word

By *uttyjonn OP Man
over a year ago

SEA

A lot of emphasis is put on the R number in the briefings, I've tried looking into how it is calculated but struggling.

My first question are they referring to 'R' or 'R0'?

I did find

'the reproduction number is calculated by dividing the number of new infections by a weighted number of infectious people'

This does strike as being another useless stat, as the number of tests increases then more new cases will be found and I've no idea how the number of infectious people is calculated

Does anyone have a link to how it is being calculated here?

By *uttyjonn OP Man
over a year ago

SEA

Thanks for the link, I might need to read it a few times

It does seem to include 'the fraction of the host population that is susceptible' in its calculation.

Because this is a new disease then I assume this will be 100% as we don't know how many people have had the virus

By (user no longer on site)
over a year ago

"A lot of emphasis is put on the R number in the briefings, I've tried looking into how it is calculated but struggling.

My first question are they referring to 'R' or 'R0'?

I did find

'the reproduction number is calculated by dividing the number of new infections by a weighted number of infectious people'

This does strike as being another useless stat, as the number of tests increases then more new cases will be found and I've no idea how the number of infectious people is calculated

Does anyone have a link to how it is being calculated here? "

Ideally R0 is the expected number of secondary cases produced by a single infection without immunity, its real value is unknown.

There are many ways to 'guess' it. They are usually based on mathematical models that use differential equations and their results usually differs a lot.

The number obtained this way

doesn't mean much by itself and you can't even compare R0 of different diseases. The 'important' thing is if it's above or below 1.

Different sources can quote different studies that calculate R0 in different ways. I believe that the UK govern bases its policies on the Imperial College works, which should use Anne Cori's Excel sheet to estimate time-varying reproduction numbers during epidemic, which itself should be largely based on Wallinga and Teunis work. L

I'm not an epidemiologist anyway, so you might want to read the full papers yourself starting from the Imperial College ones.