I have strong doubts about the efficiency of any tracing app of the sort, and even less in the context where it is unlikely that a majority of the population will use it.

There's also the problem that this app would need to work on Apple phones, or be incompatible with them, and cause significant "fracture" between those who have access to technology, and those who haven't. See this text for more details.

Such an app would be a security and privacy liability at no benefit to public health. There are better options, see for this research on hardware tokens. But I doubt any contact tracing app or hardware will actually work anyways.

I am a computer engineer with more than 20 years of experience in the domain, and I have been following this question closely.

Please don't do this.

I wrote the above in a response to the Québec government's survey about a possible tracing app.

Update: a previous version of this article was titled plainly "on contact tracing". In case that was not obvious, I definitely do not object to contact tracing per se. I believe it's a fundamental, critical, and important part of fighting the epidemic and I think we should do it. I do not believe any engineer has found a proper way of doing it with "apps" so far, but I do not deny the utility and importance of "contact tracing" itself. Apologies for the confusion.


Pour une raison que je m'explique mal, le sondage m'été envoyé en anglais, et j'ai donc écrit ma réponse dans la langue de Shakespeare au lieu de celle de molière... Je serai heureux de fournir une traduction française à ceux ou celles qui en ont besoin...

no benefit to public health?

I doubt the "no benefit to public health" part. A contact tracing app speeds up contact tracing at least in some cases and so has some benefit.

It doesn't make the number of new infections go down to zero, I also agree every implementation is imperfect and so probably generates both false positives and false negatives which quite reduces the value of such an app for an individual. Also you're fee to judge the downsides prevail. But claiming there was no benefit seems unfair to me.

Best regards

Comment by Uwe Kleine-König
Re: no benefit to public health?

I doubt the "no benefit to public health" part. A contact tracing app speeds up contact tracing at least in some cases and so has some benefit.

I didn't make that up. I based that comment on this article from the MIT Technology Preview which is titled: Nearly 40% of Icelanders are using a covid app—and it hasn’t helped much. That 40% was, at the time of writing, "the largest penetration rate of all contact trackers in the world".

I feel those comments are particularly alarming:

one senior figure in the country’s covid-19 response says the real impact of Rakning C-19 has been small, compared with manual tracing techniques like phone calls

and:

“The technology is more or less … I wouldn’t say useless,” says Gestur Pálmason, a detective inspector with the Icelandic Police Service who is overseeing contact tracing efforts. “But it’s the integration of the two that gives you results. I would say it [Rakning] has proven useful in a few cases, but it wasn’t a game changer for us.”

My fundamental concern with contact tracing app is that they try to solve a social problem (namely: reverse engineering human contacts, a fundamentally social activity) through technology (namely: by using radio transmissions as a trace of said contacts). This is bound to fail in all sorts of mysterious ways and triggers the very real risk of replacing proper contact tracing with a cheaper technological solution.

In other words, if we cheapen our contact tracing mechanisms by relying on technology too much, we can create a false sense of security and trigger new outbreaks, which will lead to more deaths.

And even if I was wrong and that you could make a contact tracing app that would be more useful than manual tracing techniques, I still doubt the privacy tradeoffs would be worth it. Maybe with a technique like the one proposed by bunnie. Maybe. But that is not what the government is proposing, in Québec, and that is that blind, I would even say ignorant, posturing that I object to.

TL:DR; maybe they are benefits to public health in contact tracing apps. I argue they are marginal enough to be non-existent, and definitely not worth the privacy trade-offs.

Comment by anarcat
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