Wednesday, August 05, 2020

More what-ifs

It was pointed out to me that my previous scenarios were roughly comparable to those produced by some experts, specifically this BBC article  referring to this report. And then yesterday another analysis which focussed on schools opening.

The experts, using more sophisticated models, generated these scenarios (the BBC image is simplified and the full report has uncertainties attached):

and for the schools opening report:

The tick marks are not labelled on my screenshot but they are at 3 month intervals with the peaks being Dec on the left hand and March on the right hand panel.

While these are broadly compatible with my analyses, the second peak for both of them is significantly later than my modelling generates. I think one important reason for this is that my model has R a little greater than 1 already at the start of July, whereas they are assuming ongoing suppression right through August until schools reopen. So they are starting from a lower baseline of infection. The reports themselves are mutually inconsistent too, with the first report having a 2nd peak (in the worst case) that is barely any higher than the first peak, and the second report having a markedly worse 2nd peak, despite having a substantially lower R number over the future period that only briefly exceeds 1.5. It's a bit strange that they differ so significantly, now I think about it...I'm probably missing something obvious in the modelling.

Of course in reality policy will react to observations, so all scenarios are liable to being falsified by events one way or another.

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