‘Disease X’ could cause the next pandemic, according to the WHO—or Ebola, SARS, or Nipah. 9 pathogens researchers are keeping a watchful eye on

The World Economic Forum's run-of-the-mill pandemic preparation session was blown out of proportion late this week, leading to the phrase “Disease X” trending on both Twitter and Google at times. (Credit: Getty Images)

The annual meeting of the World Economic Forum—to be held in Davos, Switzerland, next week—is on more radars than usual this year, thanks to the name of one of the sessions: “Preparing for Disease X.”

What is ‘Disease X’?