[cj]

Where has a contact tracing app been successfully deployed at a large scale? Have those places seen any positive effect?

Apple/Google's APIs were widely discussed a couple months ago, but (at least in the US) it seems to have fallen off everyone's radar.

[rsynnott]

Large-scale deployments in Ireland (1.4 million out of 4.9 million people) and Germany (12 million out of 80 million people), anyway. In Ireland it has lead to the discovery of a number of positive cases, which is positive; if they'd been discovered at all through conventional means that would have taken longer and the people concerned could have been spreading it for longer.

There has also been successful deployments in Taiwan and Singapore, but AIUI they don't use the Apple/Google API and are far more intrusive.

[tannhaeuser]

German app downloads have just passed 16 million [1]. Or do you mean including those who deinstalled it because it was boring ;?

[1]: https://de.statista.com/statistik/daten/studie/1125951/umfra...

[rsynnott]

Ah, no, last numbers I saw were about 12m and it seemed to have slowed down a bit. That's good news!

[tester756]

> In Ireland it has lead to the discovery of a number of positive cases,

How many?

[edaemon]

South Korea has nationwide contact tracing that's been quite successful.

Here's a study with some data on it: https://wwwnc.cdc.gov/eid/article/26/10/20-1315_article

New Yorker article that's older but adds some color: https://www.newyorker.com/news/news-desk/seouls-radical-expe...

[Polylactic_acid]

Australia has had an app for a few months now that has not provided any useful information since its creation.

[stirlo]

The Australian app (COVIDsafe) does not use the Apple/Google API becuase the Goverment wanted location tracking which is banned under their terms.

This means the COVIDsafe app chews up battery life and is vulnerable to power saving features which shut down its communication after a short amount of time on iOS in particular.

It would have been far better to use the API and obtain the location data from elsewhere (Google, Ad networks, Mobile Carriers) if really needed. If this were a less free country I'd suspect the location tracking was part of a government spying program but instead I just chalk it up to incompetence.

[Polylactic_acid]

They didn't even build the app. They just skinned an open source one which was made before the APIs came out. I doubt the government has the talent available to update it to use the new apis.

[tsbinz]

The problem with contact tracing apps is that their effectiveness has a quadratic relation with the adoption rate. They would be mostly useful to trace "random" contacts (since you tend to know which of your friends and family you saw within the last 2 weeks), but to be able to trace a possible infection both the infected and the "recipient" have to have the app and active. In Germany they said their 12M installs is "good" but that's just 15% of the population, so if you'd take a random pair the chance to detect a link is 0.15*0.15 = 2.25% ... so it's obvious that this isn't going to move the needle much. So in order for this to be effective, you need to have very high adoption rates, and it can only help in addition to other measures (wearing masks, hygene, avoiding indoor gatherings, ...)

[dwheeler]

I completely agree with you that this cannot possibly replace other measures such as masks, hygiene, and avoiding large indoor gatherings. Nor should it.

I think there is an additional confusion though. This is really an exposure notification app. If you used only this, and not traditional contact tracing, you would have to have a lot of adoption. But I think the general recommendation is to use both (1) these exposure notification applications and (2) traditional contact tracing by people trained to do it. Then you don't need as large an adoption to get utility. Traditional contact tracing can be effective, especially for people you know you contacted. But it is slow, and does not handle well the people you don't know. By combining them, there is a greater odd of notifying those who may be potentially infected. As long as you're also doing traditional contact tracing and other measures, a lower adoption rate for these applications can still be valuable.

Full disclosure, I work for the Linux Foundation. But I still believe this anyway :-).

[makomk]

The other problem is which people are likely to install the app. It basically requires a modern Android or iOS smartphone with internet connectivity, which probably excludes the really at-risk groups that are of most concern: https://www.dw.com/en/loved-or-loathed-how-germanys-coronavi...

[rsynnott]

So, elderly people are less likely to use a smartphone (though I suspect not THAT much less likely). But the people they come in contact with probably do use one, mostly. Generally these should work on any smartphone under five years old.

[Lurkars]

Trying to create hardware token for this. Because myself and many friends are not able to use this. And if I think of old people not able to handle smartphone, this should be useful. https://github.com/Lurkars/esp-ena

[salakotolu]

It has fallen off because most states have decided not to use an app. The exposure notification itself can only be leveraged by government/health officials.

I released a blog post (10min read) this past weekend breaking down digital contact tracing in the U.S. I also discussed why Google and Apple's solution isn't sufficient.

https://tolusnotes.com/state-of-digital-contact-tracing-in-t...

[davidw]

The US isn't exactly on the forefront of efforts to halt the spread of the virus, if you compare and contrast our numbers with places like Germany.

[rootusrootus]

Most iPhones now have the API available, but for some reason it has fallen to the states to provide apps that work with those APIs, and (no surprise) 90% have elected not to. I expect the feature to be quietly dropped in a future release since it's clear nobody really wants it.

[Someone]

“but for some reason it has fallen to the states to provide apps that work with those APIs”

https://developer.apple.com/contact/request/download/Exposur... gives you that reason:

“In order to use the Exposure Notification APIs, You must be a government entity, such as a government health services organization, or a developer who has been endorsed and approved by a government entity to develop an Application on behalf of a government for COVID-19 response efforts. Entitlement Profile(s) are limited to one (1) Application per country unless the country has a regional approach, or as otherwise agreed by Apple.”

[Lammy]

Nobody wants it, except the three-letter agencies who now have this baked into everyone's phones.

[cameldrv]

The Chinese Health Code app has been extremely widely deployed and has probably contributed significantly to containment. I’m not sure how much has been written about exactly how it works though.