A sprawling Singapore exhibition center known for hosting an aerospace show now has thousands of beds for patients with mild or no symptoms. South Korea used dormitories, including those belonging to Samsung Life Insurance Co. and LG Display Co., for the same purpose. Since March 4, when the country’s infectious-diseases law was tightened, people who test positive can neither decline to be isolated in these facilities nor remain at home.

In Vietnam and Hong Kong—where relatively contained outbreaks have made it possible for hospitals to take in both mild and severe cases—authorities have gone a step further. They separate not just confirmed cases but also close contacts of the sick in facilities. The reason: If the contacts are infected, they could pass on the virus to others even before they themselves develop symptoms or without ever showing symptoms at all.

This approach is vastly different from much of the West, where those that need medical care are admitted to hospitals, while mild cases, which make up the majority of infections, are largely asked to self-isolate. Many public-health experts in Europe and the U.S. say it is time to change that, while others argue it goes too far by constraining civil liberties and separating people from their loved ones.