What percentage of the population should install and use this before it becomes useful?
The latest survey in my country said less than 50% were willing to adopt it and the number in the article mentions only 20% in Singapore.
The latest survey in my country said less than 50% were willing to adopt it and the number in the article mentions only 20% in Singapore.
Figure 3 from the paper I linked contains a heatmap [0] that shows the simulated impact on r in different isolation scenarios vs. completely manual contact tracing. That's where those widely cited 60% adoption come from. In my, non-epidemiologist, view what matters more is that a) the gradient in this is better than completely manual contact tracing and b) I have yet to see anything that suggests it did not help in Singapore. While their product lead [1] is a biased source, he correctly points out that working in tandem with health authorities is critical for these efforts. If these apps aren't made only for technologies sake I do not really see how they would hurt. They have 20% there, quite some experience with outbreaks, and didn't replace it yet so I'd figure 20% would be a good enough data point for other countries to evaluate the approach on the scale of a population. And afterwards they would have to be re-evaluated constantly, just like any other measure politicians and epidemiologists currently propose to address the pandemic. We imho don't have enough data yet to even remotely answer "this amount helps", "this is how good they are" but I don't really see how that justifies these "this isn't perfect so it is dumb" reactions in the other direction.
[0] https://science.sciencemag.org/content/sci/early/2020/04/09/...
[1] https://blog.gds-gov.tech/automated-contact-tracing-is-not-a...
I don't oppose a tracking app (it could be an api baked into the os but let's call it an app to simplify things). Maybe I'm wrong but that paper only addressed the (bio)tech side of things instead of also considering the sociological implications.
If governments rely on this app to do the work of human tracers, I think the initial adoption rate will be high but then fall dramatically. This is the sociological effect I'm talking about. What happens if the app flags them as possibly infected? Can they call a hotline to give them information or is it just some automated crap they hear? How many times do you think someone would get a false positive before they uninstall it? It works using bluetooth. How much power drain on their batteries are they willing to accept?
I see this app as an aid to human contact tracing not as a replacement. Maybe this is a naive interpretation, but I see it more useful in this situation:
vector: "On date X I met with Zoe, Alec and Ronnie"
tracer: "There's a fourth with the same timestamp here"
vector: "A fourth?? I don't remember a.. Oh... right... uncle dave was also there"
The problem is companies and some governments have abused privacy information and now the consequence is that people are more reluctant to give this useful info. That's why you need to study this also from a sociological point of view.
> What happens if the app flags them as possibly infected? Can they call a hotline to give them information or is it just some automated crap they hear?
The new vendors here in Germany were especially chosen with the argument that they are able to operate 24/7 human phone support. With the decentralized approach they'll get a lot of people flagged and at the moment it seems like the app would suggest to them to call up that number (or likely offer that as an alternative to the other established contact points). Those phone contacts could then talk them through the next steps or, should testing become too limited at any point, through an assessment if testing makes sense for them / voluntary self quarantining can be done / ...
> It works using bluetooth. How much power drain on their batteries are they willing to accept?
In centralized models as proposed by PEPP-PT/ROBERT(France) or NHSX(UK) there's a few ways explored to minimize battery usage on Android, the APIs on the iphone require the screen to be turned on for this use case and must subsequently be horrible for battery usage. The decentralized model that was adopted adopted by many countries is supported by Google/Apple as OS vendors with battery usage and interoperability with other Bluetooth usage in mind, I doubt there will be much of an impact (at least not any that would drive significant user numbers away from voluntary use).
IMO these apps will be most useful as a tool to assist manual contact tracing teams at first.