Have any nations found success with that strategy? Could it be that we simply couldn't conduct that level of investigation fast enough at scale to be effective? And are the tests accurate enough for that approach to work?
It's my understanding that this is what South Korea, Hong Kong, and possibly Taiwan did (and are still doing). As well as China once they acknowledged the outbreak. (Which is not to condone China's methods of enforcing the quarantine.)
I'm just a lay observer of all this, not an authority. But my impression is that the U.S. could have done it effectively if a) the CDC test situation had not been borked and b) the federal govt had acknowledged the risk of epidemic (because I expect it's the CDC who has expertise in this tracing exercise, much more than state health departments).
As to whether it's too late, I honestly don't know. But it seems like it would be useful in controlling the epidemic regardless of its state.
