The same team’s second paper uses new evolutionary analysis, combined with the case reports, to narrow down the most likely date of SARS-COV-2 emergence in Wuhan to late November 2019 – the time that the live animals were on sale.

Finally, they also use this analysis to propose that the ‘B’ variant likely came into humans first. Since the ‘A’ variant is the ancestor of ‘B’, this would indicate at least two separate introductions into humans AFTER they diverged from one another. Essentially, this suggests that two spillover events occurred in quick succession, followed by human-to-human transmission in the market and then out into the local community.

A third study from the Chinese Centre for Disease Control analyses the same environmental data. It sticks to the official line that no live animals were discovered in Huanan and comes to a different conclusion – the market was a ‘super-spreading’ event and the origin of the virus must be elsewhere.

But inadvertently, the Chinese study supports the other two. They found an ‘A’ variant inside the market itself in the environmental sampling. This is unexpected and its presence makes the “two spillover” hypothesis in the market stronger.

Together the preprints make a strong case for Huanan market being the emergence point of SARS-CoV-2 in Wuhan. It isn’t definitive though – no infected Racoon Dog was found in the market, and samples collected by Chinese investigators that would allow scientists to assess whether DNA from them was present have not been released. Likewise, no systematic investigation of animal traders operating in Huanan has been performed – at least not publicly. And, of course, the early data is incomplete.

But although none of these studies have yet been peer reviewed, their results are difficult to reconcile with a laboratory origin theory of SARS-CoV-2. That doesn’t mean the World Health Organization should leave any stone unturned in their ongoing inquiries. And the international community needs the Chinese authorities to be open about the early events of the pandemic.

However, if this pandemic is a result of live wildlife trading in Chinese and southeast Asian wet markets, we must demand an end to these practices.

A worrying recent paper found evidence of regular cross-species transmission of viruses, including bat coronaviruses, between game animals sold across China. It happened in 2002. It probably happened in 2019. And it will happen again.

• Stuart Neil is a Professor of Virology at Kings College London

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