Viral: The Search for the Origin of COVID-19

But bat coronaviruses generally do not have furin cleavage sites, raising the question of how Sars-Cov-2 had acquired its own. RaTG13, the virus that the Wuhan Institute had admitted working with, was the closest known viral relative of Sars-Cov-2, but by virology standards it was still relatively distant, and it lacked the furin cleavage site.

They also realized that other coronaviruses in the same family as Sars-Cov-2 did not have a similar password, much less one positioned so well. That finding raised the question of why Sars-Cov-2 did. A few scientists speculated openly whether the virus had been designed or modified in a laboratory. But most dismissed those questions as irrelevant,