As the coronavirus pandemic began sweeping through South Korea late in February, Dr. Nam Ha-jong received an order to report overnight to Daegu, a city that was to become the epicenter of infections.

With little formal training in treating virus victims and just two hours of instruction in the use of personal protective gear, the 30-year-old was sent to track down likely patients.

As fear of the new disease gripped the country, Nam went door to door from dawn to dusk each day, wearing full protective gear to perform the testing of members of a secretive religious group at the center of the outbreak.