Gattaca Dna film in Future
DNA is your label from day one and you can be traced by it and this app wont collect personal info ?
Might be used to limit our travel and reason for ? Already although not stopping us useing cash it is being made more difficult . 
As ever Dave, you speak in riddles and we would expect nothing less

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As I understand it the App is completely anonymous. In other words 'the system' doesn't know who you are. It works on low-power Bluetooth, where phones (and the App within them) interact with each other. At some point your phone might send you an alert which is generated by the App, and I guess the information leading to this will come from a 'Cloud'.
If you receive an alert to warn you you've been near an infected person, then the App will advise you to self-isolate.
AFAIK that Cloud will only be looked at in general numbers-terms (to see national trends in infection rates etc), it won't be interrogated to find or identify
actual people.
The only bit I'm not sure about is how 'the system' knows who is a transmission risk. Presumably the App will ask you if you have various symptoms, and whether you've had a test to say you're positive for the virus. The former would mean a high likelihood of you having Covid, the latter would mean you
definitely have it. On the basis of either of those, the Cloud will issue a warning to the owners of any phones that have been near the phone owned by that individual.
Of course the possibility is there for 'dark forces' (MI5, the govt) to recognise actual people if they so wished. You just have to trust them on that

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The alternative is not downloading the App, and then it becomes pointless, which seems a shame because they've spent weeks working on this and it has the real power to help control the spread of CV.
So once again, it all comes down to how socially responsible people feel, ie whether they're just worried about themselves or whether they feel part of society which they want to help protect.