Suppressed Chinese Covid ‘origins’ data published and reviewed in leading journal
Importantly, it also includes analysis of the early dynamics of Sars-Cov-2 and found genetic evidence that the early strains were present in the same areas of the market as wildlife.
“The most recent common ancestor of sequences from the market matches the most recent common ancestor of the pandemic, which is consistent with an origin in the market,” Dr Débarre said. “Another way of phrasing it is that early Sars-Cov-2 diversity was represented in the market from the very beginning.
“It’s not possible to prove that the animals were infected or not infected using the data. However, the pattern that we see is consistent with the animals being infected. Likewise, the fact of having both early lineages A and B in the market doesn’t prove that the market is the origin, but it is what you would expect if it were.”
She added: “It is something of a big piece of information, when you consider the scale of the whole city of Wuhan and its 12 million inhabitants.”
Prof Edward Holmes, an evolutionary biologist and virologist at the University of Sydney and co-author of the report, said the fact both the early lineages of Sars-Cov-2 were in the market is consistent with the “multi-jump theory” that Covid jumped from animals to people on several separate occasions.
Other experts not involved in the paper said the data was “as good as it gets”, given how much time has passed since Covid-19 first emerged.
“It does add another layer of evidence that wild animals, being traded inside the Huanan market, were the very likely source and therefore origin of the Sars-CoV2 pandemic,” said Prof Jonathan Ball, deputy vice-chancellor of Liverpool School of Tropical Medicine and professor of molecular virology.
“Finding genetic material from key animal species, like civet cats and racoon dogs … in the same samples as testing positive for the presence of Sars-CoV2 is as good a smoking gun as we are ever likely to get.”
But despite “providing very strong evidence” there remain limitations, noted Prof James Wood, an infectious diseases epidemiologist at the University of Cambridge.
“The limitation of the work is that market samples were not taken before the market closed around 1st January 2020 and the pandemic viruses are thought to have arisen four to six weeks before this date,” he added.
“The virus results are what one might expect to find had the pandemic originally arisen around a wildlife market stall or stalls – but they cannot provide direct evidence of this simply because of the sampling dates.”
He added that the paper – which comes only a few weeks after a study in Nature found a concerning bat coronavirus among 36 novel viruses detected in Chinese fur farms – is an “important” reminder of the threat posed by wet markets.
“While efforts have been made globally to tighten up on laboratory biosecurity to ensure that viruses cannot inadvertently escape … little or nothing has been done to limit either the live trade in wildlife, nor the biodiversity loss or land use changes that are the actual likely drivers of past and future pandemic emergence,” Prof Woo said.