NHS Test and Trace is now up and running.

The explainer is here: https://www.gov.uk/guidance/nhs-test-and-trace-how-it-works

It relies on all of us playing our part, helping 'to contain the virus by reducing its spread'. 1/

If you have symptoms, you must self-isolate for 7 days, and your household for 14 days. You must also order a test. If you test positive you must (online or by phone) share details of people you have had contact with and places you have visited. 2/

If you are told by the NHS that you have been in close contact with someone who has tested positive, you must isolate for 14 days (even if you do not have symptoms). If you develop symptoms, you must book a test... 3/

This system will be supplemented by an app, which will presumably be ready soon. 4/

It is all too easy to see ways in which this system may be sub-optimal.

It relies on an effective testing and tracing mechanism. The longer it takes to get test results, and for contacts to be traced and contacted, the more the virus can spread. 5/

It also relies on our cooperation. It relies on all of us to identify symptoms, self-isolate, and to identify our contacts accurately. 6/

It doesn't work in environments like public transport, where you may not know who you have been in close proximity with.

And what are the consequences of (eg) a member of a school community testing positive? How will this be followed up? 7/

The Govt is trying to explain how the new system will work, with @MattHancock agreeing to do TV interviews.

It is even producing (primitive ( @jonworth) flow charts.
https://twitter.com/DrTomWalker/status/1265771658054426624?s=20 8/

There are implications for employers, for data protection and fraud, and in relation to enforcement (on which the Govt has been very vague). 9/

The system doesn't look 'world-beating' to me... there seem to be all too many ways in which it might fail. Fingers crossed. 10/10