Figuring out what economic activities are consistent with ongoing containment of COVID-19 is a trillion dollar policy question.
Currently we don't have great evidence on what policy or behavioural interventions are doing most to reduce the spread of the virus.
Is home isolation necessary? How much impact does it have to close subways or offices or schools or cafes, etc? We're forced to make educated guesses.
If every day a country/city randomly surveyed 1,000 people to see if they had an active case of COVID-19, we could use that to infer what impact policy shifts were having.
For instance, you could open the schools on a given date, and track how that affects case numbers in that survey 1-2 weeks later.
It's only going to be suggestive evidence because so much else is going on at the same time.
But if many countries or cities were doing this at the same time, collectively they could contribute to our understanding of what measures make the biggest difference.
These surveys are important anyway to figure out when and how much we can loosen our physical distancing.
But unfortunately as far as I know they're not being done anywhere at the necessary scale except Iceland.