> b) You don't identify something harmless by just testing asymptomatics. True, but I think you are missing part of Daniel's proposal. You don't "just" check

> b) You don't identify something harmless by just testing asymptomatics. True, but I think you are missing part of Daniel's proposal. You don't "just" check for unique variations of the virus in asymptomatic carriers, you also check the sequence for major deletions: We would ideally be looking for a virus strain with a large(ish) deletion in an essential viral gene. This sort of mutation is easy to spot in the SARS-CoV-2 genome data, and because the genetic information has been removed, it makes the virus very unlikely to be able to mutate back into a dangerous strain. Ideally, the strain identified will have infected a number of other people in the local area too so we can know it is safe. So while you do want to verify that the sequence is not also present in "serious" cases, you are prescreening by a factor that theoretically should correlate to severity. Whether you "need" to do additional testing depends on your assessment of base risk. If you assume that almost everyone is going to be infected with a powerful strain if you do nothing, doing your testing in live cases with a strain you suspect is mild might still be justified. Ideally (as quoted from Daniel) this "testing" might be mostly satisfied by just monitoring those already infected by the original carrier(s) with the same mild strain.