Another way is to post codes at the entrances to public spaces, and insist that people beep in when they enter. Example from New Zealand: https://www.health.go

Another way is to post codes at the entrances to public spaces, and insist that people beep in when they enter. Example from New Zealand: https://www.health.govt.nz/our-work/diseases-and-conditions/covid-19-novel-coronavirus/covid-19-novel-coronavirus-resources-and-tools/nz-covid-tracer-app/nz-covid-tracer-qr-codes https://www.health.govt.nz/our-work/diseases-and-conditions/... Obviously you need an alternative workflow (paper guestbook?) for those without devices, and either way without a person stationed there it's harder to police if people are actually complying with it.