Even if they do that, they can only track the people who self report as contaminated for the period during which the self reporting applies (i.e. n days before testing positive). Not before, not after.

But I just can't think of a system that achieves contact tracing while no one having any idea of the whereabouts of a person who self declares as contaminated. At one point the person who self declares has to volunteer to disclose some information.

I think its important to give the power to the people by allowing them to omit tokens from sensitive time points. In the current protocol, that means losing a whole days worth of contacts. If you reduce the period to an hour, you still allow people to share the contacts made on their commute or their lunch break without divulging or tracing them back to more sensitive time periods they don't want to be traced back to.

That’s one side of the ethical question, but what about the other side, what about the people who have been in contact during the period where the infected person would rather not have its location disclosed?

And it is a bit theoretical, as the authorities who have the capability to track your blutooth across the city have many other ways to track you (starting by calling your phone service).

What I object here with the NHS is the creation of one more tracking database with the explicit intention to let some researcher roam through it to find something interesting.

I appreciate you looking at the other side. To explain my view point, in this system it seems like all of the risk is put on the infected party who reports themselves. By decreasing the level of control they have, I believe you will see a decrease in the number of adoptions. It is valid to think about the non-infected user wanting to have this information, but today they don't even have this information so to even know they were exposed on their commute is above and beyond what is in place today.

I guess my original comment is a bit vague. When I look at these protocols I am interested in how large scale adversaries (Nation State) would use this technology, but also small scale adversaries (day-to-day person you are not friendly with). I think its also important to note as others have, that being outed as having the virus does put people at risk of violence in some places.

Telling people when they've been exposed is not a kindness we might extend from the goodness of our hearts when convenient. It's something we must get right, every time, or the conditions that require lockdown today persist until vaccination. We cannot afford people out and about making untraceable contacts three weeks for now, any more than we could three weeks ago.

Every person is a danger to society until this is over. Release is out of the question. The choices here are continued incarceration, or parole.

I can sort of imagine a libertarian solution here, with truth in labeling: as long as I can tell before I get within six feet of you whether you share a connected component with any conscientious objectors, then I can make my own decision about risk. But I cannot imagine that many public places would permit entry to such people.