5 ms·

> [...] and Bluetooth -- just aren't accurate enough to capture every contact. Did I miss his paper on the matter? There's dozens of groups working on this and

> [...] and Bluetooth -- just aren't accurate enough to capture every contact. Did I miss his paper on the matter? There's dozens of groups working on this and even with a regular free space model the results seem "good enough" in <2m,15min scenarios for an additional data point. Most of this seems to leave out that digital contact tracing is not a cure all but a tool to help manual efforts. I somewhat hate the simplification people bring here, that every additional identified contact helps, but dismissing it as "plain dumb" seems rather shallow as well. Sure, false negatives will be a thing, the false negative rate of not doing digital contact tracing at all would be higher by definition. Most of what he outlined can occur in manual contact tracing as well and we still do that, simply because it's necessary. I haven't seen anything so far that would suggest that digital contact tracing in the poster child Singapore had any of the negative impact he brings to the table here and studies like Ferretti et al. [0] seem to make a pretty good case why it would at least not hurt the overall epidemiological goal. > It's not accurate enough for you to quarantine yourself for two weeks. And without ubiquitous, cheap, fast, and accurate testing, you can't confirm the app's diagnosis. So the alert is useless. The time frame and assumptions on testing capability is US centric I assume? If you can get a quick test it would not be two weeks, it's likely quick tests will become more prevalent if this sticks around long enough and testing capability will be raised to sufficient levels. Otherwise yes, false positives would quickly diminish usage. Of course some of his points are valid and need to be addressed by OS vendors, apps and policy makers, and evaluation of efficacy will be just as critical as teaching the public that having an app does not mean things can go back to normal. There's also plenty of opportunity for abuse even with the commonly decentralized architecture that is at the moment widely agreed upon but none of that supports the allegations of this particular article imho. The comments similarly bring up things like "surface transmission" as if that mattered at all. If you treat a contact tracing app as an additional data point it becomes much more sensible. [0] https://science.sciencemag.org/content/early/2020/04/09/science.abb6936 https://science.sciencemag.org/content/early/2020/04/09/scie...

nocturnial 6y ago
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.
- tastroder 6y ago
  That completely depends on your definition of useful, how people react to a "hit" in the application, and a bunch of other factors honestly. 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/science.abb6936/F3.large.jpg?width=800&height=600&carousel=1 https://science.sciencemag.org/content/sci/early/2020/04/09/... [1] https://blog.gds-gov.tech/automated-contact-tracing-is-not-a-coronavirus-panacea-57fb3ce61d98 https://blog.gds-gov.tech/automated-contact-tracing-is-not-a...
  - nocturnial 6y ago
    Thanks for taking the time to type out this response. I had scanned the paper you posted and failed to make the link between success to isolate and adoption of the app. It's messy and a bunch of factors come into play, I now understand this better. 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.

nocturnial 6y ago

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.

tastroder 6y ago
That completely depends on your definition of useful, how people react to a "hit" in the application, and a bunch of other factors honestly. 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/science.abb6936/F3.large.jpg?width=800&height=600&carousel=1 https://science.sciencemag.org/content/sci/early/2020/04/09/... [1] https://blog.gds-gov.tech/automated-contact-tracing-is-not-a-coronavirus-panacea-57fb3ce61d98 https://blog.gds-gov.tech/automated-contact-tracing-is-not-a...
- nocturnial 6y ago
  Thanks for taking the time to type out this response. I had scanned the paper you posted and failed to make the link between success to isolate and adoption of the app. It's messy and a bunch of factors come into play, I now understand this better. 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.