The Lancet medical journal has published an article calling for an "objective" and "transparent" debate about the true origins of the SARS-CoV-2 virus, more than a year and a half after its controversial article condemning "conspiracy theories" that suggest the virus leaked from a laboratory in China.

The article published Friday, titled, "An appeal for an objective, open and transparent scientific debate about the origin of SARS-CoV-2," is signed by 16 scientists arguing that a laboratory-related accident is "plausible," as is the virus having a natural origin, and that neither theory should be ruled out yet.

"On the basis of the current scientific literature, complemented by our own analyses of coronavirus genomes and proteins, we hold that there is currently no compelling evidence to choose between a natural origin (ie, a virus that has evolved and been transmitted to humans solely via contact with wild or farmed animals) and a research-related origin (which might have occurred at sampling sites, during transportation or within the laboratory, and might have involved natural, selected or engineered viruses).".

The authors criticized a controversial "statement in support of the scientists" article published by The Lancet in February of 2020 that declared, "We stand together to strongly condemn conspiracy theories suggesting that COVID-19 does not have a natural origin." That letter, signed by 27 experts, warned that the sharing of data on the COVID-19 outbreak was being "threatened by rumors and misinformation" surrounding its origins. .

In July, the same group of experts in the 2020 letter published another letter reaffirming their belief that COVID-19 evolved in nature while urging others to "turn down the heat of the rhetoric and turn up the light of scientific inquiry.".

The authors of Friday's letter argued that the other group's statements have had a "silencing effect on the wider scientific debate, including among science journalists."