When hospitals in the South Korean city of Daegu were overwhelmed by coronavirus patients, officials appealed for doctors to help, and among the volunteers was multi-millionaire and former presidential candidate Ahn Cheol-soo.
The South was one of the first countries hit by the virus outside China, where it initially emerged, and for a time had the largest number of confirmed cases outside the Middle Kingdom.
But an extensive "trace, test and treat" programme -- facilitated by rapidly approved kits and a widely adhered-to social distancing campaign -- has seen it apparently brought under control, with fewer than 10,000 cases as of Wednesday and one of the lowest death rates anywhere.
As part of that drive authorities sought to test every member of the Shincheonji Church of Jesus, a religious group often condemned as a cult, which is still linked to more than half the South's cases.
As a result, a deluge of positive cases emerged in Daegu, the epicentre of the outbreak, where a Shincheonji member attended four crowded services before being diagnosed.
With the city's hospitals overflowing, a doctors' association issued a call for help and Ahn, 58, and his medical professor wife were among hundreds who have stepped forward.
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He was soon treating up to 90 intensive care patients daily, with pictures showing him looking drained but determined in sweat-soaked medical scrubs.
"One patient in her 60s told me her husband died from coronavirus just a day before at another hospital," he recalled.
"But she couldn't see his body one last time because it had to be cremated right away. She couldn't even attend his funeral because she herself was infected."