There is no scientifically-validated evidence to support the theory that Covid-19 leaked from a laboratory in China, while more recent studies strongly indicate it evolved in nature, a group of 23 prominent scientists have concluded.
In a letter to The Lancet, the biologists, ecologists, epidemiologists, physicians, public health experts and veterinarians from around the world – but mainly based in the US – confirmed their view had not changed since they first issued their verdict in February of last year.
The same team then dismissed the lab-leak idea as a conspiracy theory in a report also published in The Lancet.
“We believe the strongest clue from new, credible, and peer-reviewed evidence in the scientific literature is that the virus evolved in nature, while suggestions of a laboratory-leak source of the pandemic remain without scientifically-validated evidence that directly supports it in peer-reviewed scientific journals,” they said in a letter to the medical journal.
The latest report comes as many countries have called for further inquiry into the origins of Covid-19, including the possibility it escaped from a lab in the Chinese city of Wuhan, where the first cases were reported in December 2019.
US president Joe Biden last May ordered intelligence officials to "redouble" efforts to investigate the origins, including the theory that it came from a Chinese laboratory.
However, the authors noted: “Allegations and conjecture are of no help as they do not facilitate access to information and objective assessment of the pathway from a bat virus to a human pathogen that might help to prevent a future pandemic.”
They added: “New viruses can emerge anywhere… It is time to turn down the heat of the rhetoric and turn up the light of scientific inquiry if we are to be better prepared to stem the next pandemic.”
They welcomed calls for scientifically-rigorous investigations into the origin of the virus.
“To accomplish this we encourage WHO and scientific partners across the world to expeditiously move to continue and further extend their initial investigation with experts in China and the Chinese government.”
WHO’s report from last March must be considered the beginning rather than the end of an inquiry, they underlined.
That inquiry found, following a visit to Wuhan, that a lab leak was unlikely. However, many countries had expressed concern about the way the investigation was carried out and called for more transparency.
The authors strongly support, nonetheless, the recent call by G7 leaders for "a timely, transparent, expert-led, and science-based WHO-convened phase 2 Covid-19 origins study".
They acknowledged this could require “years of field and laboratory study...to reach rational and objective conclusions”, but said this was “what the global scientific community must strive to do”.
They reiterated their call for putting in place robust surveillance and detection systems across the world “to detect and report new or evolving pathogens that can potentially unleash the next local or global threat”.
“Equally essential will be ensuring that the field workforce, laboratory facilities, and the healthcare community can all work under the safest conditions. Until this pandemic ends, we ask, as we did in February 2020, for solidarity and rigorous scientific data,” the letter concluded.
It comes with full disclosure including details of a small number of author links to China and Wuhan Institute of Virology.
It was submitted by scientists from Boston University; University of Maryland, the University of Glasgow, The Wellcome Trust, Charite-Universitatsmedizin Berlin, and University of Queensland, and Hong Kong University among other institutions.