A pneumonia-like illness emerged in the Chinese port city of Wuhan in December. Health officials there are concerned enough to shut down transportation to an area that includes 20 million people. The infection has spread to South Korea, Thailand, Japan, and the US, but so far the World Health Organization has decided not to declare the outbreak a global emergency.

We compare the Wuhan coronavirus to the Spanish flu of a hundred years ago, discuss the potential for it to become the “Disease X” that health officials fear, and explain why this disease, and SARS before it, can be traced back to a Chinese outdoor meat market.

See every new episode at www.SciFriday.tv!