On February 16, a Sunday, a 61-year-old woman with a fever entered the Shincheonji Church of Jesus in Daegu, South Korea. She touched her finger to a digital scanner. She passed through a pair of glass doors and proceeded downstairs, to the prayer hall, where she sat with approximately 1,000 other worshippers in a large windowless room. Hours later, she exited the building and left behind a trail of pathogens that would lead to thousands of infections, triggering one of the largest coronavirus outbreaks in the world.
By the end of February, South Korea had the most COVID-19 patients of any country outside China. New confirmed cases were doubling every few days, and pharmacies were running out of face masks. More than a dozen countries imposed travel restrictions to protect their citizens from the Korean outbreak, including the U.S., which had, at the time, recorded an official COVID-19 death toll low enough to count on one hand.
But just as South Korea appeared to be descending into catastrophe, the country stopped the virus in its tracks. The government demanded that the Shincheonji Church turn over its full membership list, through which the Ministry of Health identified thousands of worshippers. All were ordered to self-isolate. Within days, thousands of people in Daegu were tested for the virus. Individuals with the most serious cases were sent to hospitals, while those with milder cases checked into isolation units at converted corporate training facilities. The government used a combination of interviews and cellphone surveillance to track down the recent contacts of new patients and ordered those contacts to self-isolate as well.