"The new coronavirus is a close cousin of viruses that infect bats. It jumped from an unconfirmed wild source (most likely bats) to an intermediate host, possibly pangolins, or other small mammals, being sold as food at a market in Wuhan, a transportation and commercial hub in central China. The infected people unknowingly spread it to others, setting off the outbreak’s deadly journey. We now estimate that it takes about five to six days—possibly upward of 14 days—for someone to show symptoms after becoming infected."

Gabriel Leung, an infectious disease epidemiologist and dean of medicine at the University of Hong Kong, writing in The New York Times about “The Urgent Questions Scientists Are Asking About Coronavirus.”