Again, as the authors of this study said, all you have to do is do an antibody study and you can find out really quickly. See who has already had it/immune. And if it’s not saturated in SK, it will come back with so many people assymptomatic.
But, once it turns over and peaks that does not mean you have saturated the population. You have just broken the chain reaction which most communities have done through social distancing or in the case of SK Taiwan , HK and Singapore, rapid thorough and accurate contact tracing and isolation.