Thanks to the folks at @cmmid_lshtm and @SacemaQuarterly, and particularly @carivs, @kathmoreilly, Anna Foss, and @SACEMAdirector. This work is now peer reviewed at: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.18.2000543

I want to use this opportunity to talk about "wrong" forecasts. https://twitter.com/cap1024/status/1243514619618045959

We forecast dates that African countries would *report* 1K and 10K cases. We used very sparse data (first 25 or fewer cases prior to 23 March), w/ deliberately low-detail method (branching processes), assuming global epi estimates & discounting any potential interventions.

That very simple approach worked well for countries that couldn't (or didn't) respond to early warnings like ours. My previous tweets about this report are from 27 March; since then 12 countries have reported >1K cases: https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200506covid-19-sitrep-107.pdf

However, then (& now) we forecast that *if people did nothing* that by now all 45 countries / territories we considered would have likely confirmed >1K COVID-19 cases.

Why so "wrong"?

https://www.eurosurveillance.org/docserver/fulltext/eurosurveillance/25/18/2000543-f1.gif

Hope this is no surprise: people decided to respond to warnings like ours. Instead of the ~450K cases we forecast, there are roughly 1/10th.

I think we could have spent more time on this work and gotten a more accurate forecast. Should we have?

Many African countries started some interventions prior to that tweet (& a few prior to an earlier version sent via other institutional channels). Won't pretend ours was only, or even most important, voice urging action. Could have tried to update forecast to account for that.

But what would be the point? We *know* a full-blown epidemic is impossible to steer. We *could not know* if what was then being done was enough, so we shouted for the brakes. Today, what we report remains useful to describe the plausible benefit of current interventions.

Now that we aren't careering out of control, we have to decide how to steer. There are a lot of tough decisions balancing economic welfare--meaning survival, not wealth--and control of #COVID19, but we are still in a position to make decisions, rather than possibly over a cliff.

@threadreaderapp please unroll