South Korea became one of the world’s top virus success stories by learning from past experiences. Now it’s using lessons from a fresh spate of clusters to prepare for what officials say will be an inevitable second wave.

The nation once had the world’s second-worst outbreak, but it was quelled without ever having to lock down cities or impose heavy restrictions on social gatherings.

Instead, Korea launched a massive, technology-reliant testing and tracing campaign, a by-product of lessons learned from its bitter experience with Middle East respiratory syndrome in 2015. The country’s mass testing and contract tracing garnered praise as a model for handling the virus.