TED is explaining concepts again:
h**ps://
www.youtube.com/watch?v=f4xu7w6Vf0U
Here is a short writeup.
More info on contact tracing.
Contact tracing in principal is a way to massively reduce need for universal testing - basically everyone - every two (or so) days, by making it 'smart'.
Which is needed, because testing everyone every two (or so) days is a magnitude over what will be available in testing capacity.
So the idea is, once someone is tested because of symptoms, or harsh progression, you can follow up on them, and then have people they were in direct contact with also test (or self quarantine on the spot.
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If you are at a low enough daily growth rate, and following up on individual cases is possible, what you are planning to do is massively increasing testing capability - doing those "smart ("one degree of Kevin Bacon") tests", and thereby being able to get by with individual quarantines. Instead of nation or region wide ones.
There also is a statistics angle to it that makes it interesting to look at spread rates and so forth - which favors the app approach.
Currently voluntary or not is still discussed, states usually would like to force it on people, because economic fallout (need for bigger quarantines) can be reduced, but at the same time - they get told, that acceptance might be higher if they don't.
Also you dont have to do it via an app, you could also do it via patient interviews - but it would be less thorough (earlier growth rate increases would be expected).
The idea is, that you combine it with a massively increased testing capability (for which you need different tests that the earlier ones) - so as a result you can now quarantine infected people individually - instead of entire populations.
Also - what you do aside from that are randomized tests on representative populations, so you can keep track of growth rate in the general population. If growthrate starts to get close to 'doubling every three days' again - you have to do national or regional quarantines again.
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Target is either to hit the 12-18 months mark doing that (when a vaccine becomes available to the public at large (not just risk groups)), or until you hit 60%-70% of you populations having been infected (herd immunity).
For reference, in italy infection rate in the general public is (only) at about 15% currently. So you'd have to repeat what happened there four times until you reach goal. Obviously you cant - in the same timeframe of a couple of months (repeat the same crisis there four more times) - so you try to stretch it out.
Interestingly they are talking about testing people who you have contact traced for a tracing duration of two weeks to every infected person, while the 'app' promoted to do that in Austria would only do that for a period of three days. Thats still a pretty stark variability between approaches..
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There seem to be some estimates on deaths being underreported in italy floating arround that talk about probably twice the number of deaths than reported. If we take that number and the 15% infection rate estimated, we end up with a case fatality rate of 0.4% - which would mean roughly a million people dying in the US (if your progresion is similarly as in itally and it only stops 'naturally' at 70% of the population infected). All of that is ballpark math.
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Psionic Roshambo:
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