Time after time this year, South Korea prevented the coronavirus from spreading uncontrollably, applying its elite testing-and-tracing practices that have become a global model for managing the pandemic without draconian, economy-sapping lockdowns.

Now, this "living with the virus” strategy — as the nation of 51 million calls it — is being tested like never before.

While case numbers are still small compared to the U.S. and parts of Europe, Korea saw new infections top 1,000 for five consecutive days through Sunday, a staggering jump from an average of about 100 in previous months. The fierce winter wave has alarmed a country that’s drawn pride from being globally lauded for its COVID-19 response.