Pan-European Privacy-Preserving Proximity Tracing

Suppose Alice is permanently at home with only one caregiver. The system should never tell Alice that she has been in contact with a virus carrier because that will imply that the caregiver tested positive.

Instead, the system should rather tell Alice she may have been exposed to the virus and should get tested. Bloom filters can provide that uncertainty.

And can that be opensource as well. What's your point?

It’s specifically set up to protect privacy. If governments didn’t care, or had anything near the power and data that conspiracy theorists always assume they do, or felt justified to disregard the law, or empowered to change it, they’d tell Apple & Google to flip the switch and all location matching would happen tonight, in some unlucky eurocrat’s excel table.

> Furthermore, you have to ask yourself why such an initiative suddenly springs to life exactly at this time.

I don’t get this paragraph at all. It’s no mystery why this is happening now and didn’t happen last year: there’s a pandemic on.

I realize you say as much. But somehow, with the “no more, no less” and “technological experiments” you make it sound sinister. Like C-SPAN, but with an iMovie horror sound & lighting preset.

> 1) Transmission via surfaces is thought to be important (afaik).

According to Hendrik Streeck, a leading researcher in Germany, this may not be the case: https://youtu.be/VP7La2bkOMo?t=231

They are working on a more formal study of this but indications are that the viruses that other teams have found on surfaces may be "dead" (in the sense that they cannot actually replicate anymore and therefore are not bioactive relatively soon after leaving host organisms).

Video only in German, sorry, sure this will get publicized internationally if the study confirms the indications.

They should do a dead-simple PoC to demonstrate this actually working with Bluetooth. Just make a stupidly simple test app, get 100 volunteers to install the app, have them all wear masks etc. while walking around randomly in the same big room for half an hour.

Then see what the false negative rate is - unless the average number of "others seen" is close to 100, this isn't going to work.

Ad. 2 - it is not that bad: duration of proximity is correlated with both infection probability and connection probability.

1) That would be difficult to solve. If we used position reporting, and considered an area infected for a few days after an infected person arrived, it would most likely lead to unmanageable amounts of false positives.

2) Scanning is mostly just listening and waiting for other devices to send beacons. With one discoverable device nearby, it might take a moment to hear anything. With 50 devices nearby, you scan should be spammed with results.

You might have missed a few devices if you were unlucky and moved out of range before they got a successful beacon through. However, in that case you could use second-hand proximity to find the "lost" contact through some of the successful ones.

Surfaces can be cleaned easily and should be cleaned frequently. (Eg on public transport.)

Furthermore any kind of app will only reach a subset of the population. (Senior citizens are unlikely to install this app.)

Yes, bluetooth drivers are a horrible hellscape of cyberspace, but it's probably because connecting to a sink/source (speaker/mic/camera/whatever) sets up the corresponding audio/media/etc channels too, and the interaction of the relevant components (pairing, PIN, kernel modules, gstreamer or who knows what) is what requires a very fragile dance. I have no idea how broken the BLE part is.

Firechat doesn't seem that bad and it uses Bluetooth too.

sharing a timeline of access points and timestamps is somewhat similar to a timeline of gps coordinates and timestamps. there is a lot to infer from such data and can potentially reveal the identity of the person who got sick and shared their data

South Korea managed to control the spread by endless testing and then contact tracing and notification and quarantine.

They didn't lock down the cities. They did it and continue to do it without locking down.

They are staying flat now because they continue to do that.

This is a tool to help that second part of contact tracing. No one is saying it's a replacement for social distancing, but it enables us to relax it if there's a way to stop detected infections spreading.

Nobody is talking about it as a "replacement" (for what anyway).

It's viewed as part of the recipe that countries with SARS and/or MERS exposure learned that helped them to handle this situation better than others.

Ah yes, you are right, my previous comment is not applicable here.

A relevant datapoint here is the case of Webasto in Germany. The woman who infected employees of Webasto and thereby unwittingly created one of the first clusters in Germany was traveling, ate in restaurants etc. Yet the only known infections happened with her colleagues at Webasto, ie those with whom she sat in proximity close and over an extended period.

That indicates that infection „requires“ (or is favored) by extended proximity. It may also indicate that infection by aerosols is more „difficult“ and droplets may be more relevant —> masks!

I am writing this not to say all-safe but to caution against overexcitement/-anxiety/panic. Caution is good but it seems infection is not as easy or fast as mainstream media are touting atm.

As I understand this, the approach here is to bet on personal responsibility. This technology cannot be used to enforce quarantines as the authorities have no access to the data.

Basically, we have to stop 2/3 of infections to get an R<1. If 2/3 of the population use the app honestly and we keep up some other measures (no indoor events where people are in close contact, wearing masks while shopping, no visitors in nursing homes and hospitals, etc.) then this might be enough to contain the virus until we have a vaccine.

Good point. Hadn’t considered that.