Experts studying the origins of the coronavirus for the World Health Organization warned on Wednesday that the inquiry had “stalled” and that further delays could make it impossible to recover crucial evidence about the beginning of the pandemic.
“The window is rapidly closing on the biological feasibility of conducting the critical trace-back of people and animals inside and outside China,” the experts wrote in an editorial in the journal Nature. Several studies of blood samples and wildlife farms in China were urgently needed to understand how Covid-19 emerged, they said.
Amid a rancorous debate about whether a laboratory incident could
