The Biden administration is expected to declassify some information gathered on the origin of the SARS-CoV-2 virus, hoping to end a three-year battle over whether covid-19 came from a seafood market or a laboratory in Wuhan, China. Some scientists say they have strong evidence for a market origin—although many are far from convinced. Will this mystery ever be solved?  Natasha Loder, The Economist’s health editor, asks James Wood, an epidemiologist at the University of Cambridge, how to trace a virus back to its source—and why interpreting the patchy data is so complicated. Plus, Alison Young, the author of “Pandora’s Gamble” explains the implications of this investigation on laboratory safety. Alok Jha, The Economist’s science and technology editor, hosts.  We would love to hear from you. Please fill out our updated listener survey at economist.com/podcastsurvey. For full access to The Economist’s print, digital and audio editions subscribe at economist.com/podcastoffer and sign up for our weekly science newsletter at economist.com/simplyscience. Hosted on Acast. See acast.com/privacy for more information.