A group of 18 top researchers signed a letter published in the latest issue of the journal Science, calling for a new investigation into where and how the novel coronavirus originated, arguing that a satisfactory inquiry still has not been performed. “Theories of accidental release from a lab and zoonotic spillover both remain viable,” the letter reads. “Knowing how COVID-19 emerged is critical for informing global strategies to mitigate the risk of future outbreaks.” Robert Redfield, former President Donald Trump’s CDC director, has said—without evidence—that he believes the virus escaped from a lab in Wuhan, China. For its part, the Chinese government has engaged in similarly baseless speculation, blaming the U.S. Army for creating the virus. Mainstream researchers have largely come out in favor of the theory that COVID-19 originated in animals and spilled over into humans naturally, although hard evidence of any sort has thus far remained elusive.

The new letter makes no assertions or claims one way or the other, only that more research is very necessary. “[I]n this time of unfortunate anti-Asian sentiment in some countries, we note that at the beginning of the pandemic, it was Chinese doctors, scientists, journalists, and citizens who shared with the world crucial information about the spread of the virus—often at great personal cost,” it concludes. “We should show the same determination in promoting a dispassionate science-based discourse on this difficult but important issue.”