The most famous doctor in China was on an urgent mission.

Celebrated as the hero who helped uncover the severe acute respiratory syndrome epidemic, or SARS, 17 years ago, Dr. Zhong Nanshan, now 84, was under orders to rush to Wuhan, a city in central China, and investigate a strange new coronavirus. His assistant photographed the doctor on the night train, eyes closed in thought, an image that would later rocket around China and burnish Zhong’s reputation as the nation’s medic riding to the rescue.

China’s official history now portrays Zhong’s trip as the cinematic turning point in an ultimately triumphant war against COVID-19, when he discovered the virus was spreading dangerously and sped to Beijing to sound the alarm. Four days later, on Jan. 23, China’s leader, Xi Jinping, sealed off Wuhan.