I have little confidence that this app is the best way to track and trace a population of 65000000. I'd look to a human system as back up.
I agree and have been thinking along the same lines for a while. In fact, even putting aside all the legitimate concerns regarding the security of all that data, the more you think about it, the less sense it makes.
Firstly, what parameters are they going to use? If it's literally all of the people who have come within 2 metres of an infected person in the past 14 days, that could be a significant number of people for each and every one.
Even within social distancing, every time you go to the supermarket you end up within 2 metres of people in every aisle, because there simply isn't 2 metres passing space. At the checkouts, you are within 2 metres of the shop assistant, albeit they are behind a screen (which the app won't know).
If people return to work and are using public transport, will it flag up everyone who an infected person has walked past on a train or bus? What abour pedestrians walking past stationary traffic? Or people in different rooms with a thin wall separating them?
Secondly, if the app is to be effective you can't simply rely on everyone responding to a message that they should self isolate and arrange for a test. You would have to employ people to download the data and physically contact trace people to make sure you suppress the virus. In the above scenario, the level of resources required would be enormous.
Then you've got the testing facilities. We've currently got the 'capacity' for 40,000 tests per day, but only the facilities and resources to test and analyse about 20,000 per day. Even if we increase that in the coming weeks, this level of testing could easily swamp the system. And the more of those who test positive, the more people who've come within 2 metres of them would have to be traced and tested, quite foreseeably spiralling out of control.
And then there's the final, glaring, question. Why is it necessary to trace everyone who has come within 2 metres (however briefly) of someone who's tested positive?
We've been repeatedly told by the government and their scientific advisers that an infected person will, on average, infect a further 2-3 people. We've also been told that you would need to be in contact with an infected person for a 'reasonable period of time' (suggested as at least 15 minutes), in order to be at risk.
If we actually need to trace everyone who has come anywhere near an infected person, then that would make Covid-19 one of the most infectious diseases ever known. And the more infectious a disease is, the higher the level of immunity you need to get in the population in order to eventually achieve herd immunity.
Unless there is something that we're not being told, I'm not sure what's wrong with the old system of interviewing people who have tested positive and then contacting all the people they can remember coming into contact with over the previous 14 days.