New research is bolstering the notion that SARS-CoV-2 began spreading from the Huanan Seafood Wholesale Market in Wuhan.
Using genetic data, market maps, case patterns, patients' social media posts, and more, international research teams traced the coronavirus to the food and live animal market, detecting signs of two distinct spillover events, reporters Carl Zimmer and Benjamin Mueller explain in the New York Times. The groups posted pre-print versions of the papers to Zenodo over the weekend.
"The question of whether the outbreak began with a spillover from wildlife sold at the market, a leak from a Wuhan virology lab, or some other event has given rise to pitched debates over how best to stop the next pandemic," the pair writes, adding that "[s]everal independent scientists said that the studies, which have not yet been published in a scientific journal, presented a compelling and rigorous new analysis of available data."
A related Nature Portfolio pre-print study, led by investigators at the Chinese Academy of Sciences and the Chinese Center for Disease Control and Prevention, suggests that two SARS-CoV-2 lineages were present in at least some of the swab samples taken from the market's floors, walls, refrigerators, stray animals, and remaining meat samples after the market was closed and disinfected.
"In the early days of the pandemic in China, the only Covid cases linked to the market appeared to be Lineage B, And because Lineage B seemed to have evolved after Lineage A, some researchers suggested that the virus arrived at the market only after spreading around Wuhan," Zimmer and Mueller write. "But that logic is upended by the new Chinese study, which finds both lineages in market samples."
Even so, they note that questions remain, particularly since the studies did not narrow in on an animal source for the human infections that appeared to spread at the market and beyond.
On the CNN Health site, Katherine Dillinger notes that most experts "have roundly condemned the theory of a laboratory origin for the virus, saying that there's no proof of such origins or of a leak."
"Many of the researchers behind the new studies were also participants in a review published last summer that said the pandemic almost certainly originated with an animal, probably at a wildlife market," she adds.
In The Guardian, Martin Pengelly writes that "the issue of Chinese culpability or otherwise has become diplomatically sensitive and highly politicized, particularly in the US."