Have I understood correctly.
If I have a positive test, someone from the government will contact me and ask me for details of those I've been in contact with in previous days?
How many days?
I wouldn't necessarily know, for example, who I've sat near on the bus.
If I do give details, these people then have to take 14 days off work, probably on SMP or worse if SE. I'm not sure I could do that to people I'd only had relatively short or distant contact with. Could you? Or maybe I wouldn't need to? What does "contact" mean?