The fish section at the market in Langfang, China, Jan. 23, 2020. (Giulia Marchi/The New York Times)

The fish section at the market in Langfang, China, Jan. 23, 2020. The coronavirus that has spread from Wuhan has been linked to the sale of live wildlife at a market that experts describe as a perfect incubator for novel pathogens. (Giulia Marchi/The New York Times)