Most cases are not life-threatening, which is also what makes the virus a historic challenge to contain.
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.
At the U.S. Centers for Disease Control and Prevention in Atlanta, the boy’s sputum sat for a month, waiting for its turn in a slow process of antibody-matching analysis. The results eventually confirmed that this was a variant of influenza, the virus that has killed more people than any in history. But this type had never before been seen in humans. It was H5N1, or “avian flu,” discovered two decades prior, but known only to infect birds.