Researchers at the Chinese Center for Disease Control and Prevention (China CDC) have published an eagerly awaited analysis1 of swabs collected at a wet market in Wuhan, China, in the early weeks of the COVID-19 pandemic — as well as the underlying data, which the international research community has been calling for since the beginning of the outbreak.

The analysis, published in Nature on 5 April, confirms that swabs from the Huanan Seafood Wholesale Market — which closed in January 2020 and has long been linked to the start of the pandemic — contained genetic material from wild animals and tested positive for SARS-CoV-2. This suggests that it’s possible an animal could have been an intermediate host of a virus that spilled over to infect humans. But researchers say the latest findings still fall short of providing definitive proof that SARS-CoV-2 originated from an animal-to-human spillover event. (The study authors, led by former China CDC director George Gao, did not respond to requests for comment from Nature’s news team, which is editorially independent of Nature’s journal team.)


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Still, researchers say that the publication of the genomic data, which have been deposited on open repositories, is crucial — because it will allow further analyses that could offer clues about the pandemic’s origin. “It’s one of the most important data sets we’ve had since the emergence of the pandemic,” says Florence Débarre, an evolutionary biologist at the French national research agency CNRS in Paris, who was part of a team that caused controversy by publishing its own analysis of the China CDC data last month. “They exist because at the time the right things were done.”