Some really interesting stuff in this thread. Suggests even a 40% COVIDSafe uptake (in and of itself an undersell according to some) may be more difficult to achieve than seems at first glance #COVID19 https://twitter.com/DrTobyGilbert/status/1254300822428508160

When I say undersell, I mean the 40% threshold for it to be meaningful at a population level may undershoot. Eg Oxford estimates for UK app will need 80% of all existing smartphone users https://www.bbc.com/news/technology-52294896