Most cases are not life-threatening, which is also what makes the virus a historic challenge. In May 1997, a 3-year-old boy developed what at first seemed like the common cold. When his symptoms—sore throat, fever, and cough—persisted for six days, he was taken to the Queen Elizabeth Hospital in Hong Kong. There his cough worsened, and he began gasping for air. Despite intensive care, the boy died. Puzzled by his rapid deterioration, doctors sent a sample of the boy’s sputum to China’s Department of Health. But the standard testing protocol couldn’t fully identify the virus that had caused the disease . The chief virologist decided to ship some of the sample to colleagues in other countries.