Korea will have to remain on alert, forever, as their population has no established immunity. A vaciine may never come - there is no influenza vaccine (it mutates every season).

Plus, there are grim, yet economic, benefits if the sickest and most elderly die from Coronavirus, in the form of long-term savings on pensions and healthcare. This should be taken into account in strategic national planning.

The UK approach seems the most sensible - keep the economy and society functioning, and recommend that the most vulnerable practice self-isolation. Better to isolate those who are not participating in the productive economy (ie. the sick and elderly) than the entirety of the population.