May 30, 2023

expert reaction to comments from Professor George Gao on the origins of SARS-CoV-2

In an interview for BBC Radio 4’s podcast ‘Fever: The Hunt for Covid’s Origin’, the former head of China’s Centre for Disease Control (CDC), Prof George Gao, said: “You can always suspect anything. That’s science. Don’t rule out anything.”

Prof James Wood, Head of Department of Veterinary Medicine, University of Cambridge, said:

“Professor Gao is an internationally respected scientist. There is strong evidence from virus genomics that the covid-19 virus was not artificially engineered, or made by humans, but likely arose from another virus infecting wildlife. Epidemiological evidence points to the first area where the virus transmitted widely was around, but not restricted to the Hunan Seafood market. There were laboratories in Wuhan which were investigating coronaviruses in samples collected from wild bat populations.

“Genomics cannot distinguish whether the virus transmitted to humans via traded wildlife in the Hunan Seafood market or through a laboratory accident, where a laboratory worker was inadvertently infected from a sample they were processing, subsequently infecting other people.

“Field, observational epidemiology can only identify where cases are first observed and are first transmitting, and cannot distinguish where the first case, which is frequently unobserved, may have occurred. With current knowledge, it is clear that some species of animal, e.g. ferrets and other mustelids may be easily infected by infected humans in close contact. So animals in the market could have been infected by humans, or could have been the route of transmission to animals.

“As Professor Gao said, science deals in probabilities and not in certainties. In reality, it may never be possible to know with confidence how the covid-19 virus entered the human population. What is important is that lessons are learned and that live wildlife trade, a well recognised route for zoonotic virus transmission, is reduced or banned and that laboratory safety is properly regulated.”

Declared interests

Prof James Wood is currently funded by Horizon 2020/UKRI to investigate viruses infecting bats, pigs and humans in Ghana. He has previously received other funding for this type of work, including from UKRI, FCDO, Wellcome Trust.