The letter, which was organized by the Stanford University microbiologist David Relman and the University of Washington virologist Jesse Bloom, takes aim at a recent joint study of covid origins undertaken by the World Health Organization and China, which concluded that a bat virus likely reached humans via an intermediate animal and that a lab accident was “extremely unlikely.”
That conclusion was not scientifically justified, according to the authors of the new letter, since no trace of how the virus first jumped to humans has been found and the possibility of a laboratory accident received only a cursory look. Just a handful of the 313 pages of the WHO origins report and its annexes are devoted to the subject.
Marc Lipsitch, a well-known Harvard University epidemiologist who is among the signers of the letter, said he had not expressed a view on the origin of the virus until recently, choosing instead to focus on improving the design of epidemiological studies and vaccine trials—in part because the debate over the lab theory has become so controversial.
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