On December 18, 2019, Wuhan Central Hospital admitted a patient with symptoms common for the winter flu season: a 65-year-old man with fever and pneumonia.Ai Fen, director of the emergency department, oversaw a typical treatment plan, including antibiotics and anti-influenza drugs.Six days later, the patient was still sick, and Ai was puzzled, according to news reports and a detailed reconstruction of this period by evolutionary biologist Michael Worobey.