Professor Richard Ebright of Rutgers University’s Waksman Institute of Microbiology, a biosecurity expert who has been speaking out on lab safety since the early 2000s, does agree with the Nature Medicine authors’ argument that the new coronavirus wasn’t purposefully manipulated by humans, calling their arguments on this score strong. Ebright helped The Washington Post debunk a claim that the COVID-19 outbreak can somehow be tied to bioweapons activity, a conspiracy theory that’s been promoted or endorsed by the likes of US Sen. Tom Cotton, Iran’s supreme leader, a high-ranking Chinese government official, and others.

But Ebright thinks that it is possible the COVID-19 pandemic started as an accidental release from a laboratory such as one of the two in Wuhan that are known to have been studying bat coronaviruses.

Except for SARS-CoV and MERS-CoV, two deadly viruses that have caused outbreaks in the past, coronaviruses have been studied at laboratories that are labelled as operating at a moderate biosafety level known as BSL-2, Ebright says. And, he says, bat coronaviruses have been studied at such labs in and around Wuhan, China, where the new coronavirus first emerged. “As a result,” Ebright says, “bat coronaviruses at Wuhan [Center for Disease Control] and Wuhan Institute of Virology routinely were collected and studied at BSL-2, which provides only minimal protections against infection of lab workers.”