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Two newly published studies are suggesting that COVID-19 initially stemmed from animals being sold at the Huanan Seafood Market in Wuhan, China, CNN reports.
The two studies -- which took varying approaches before reaching the same conclusion -- were shared online as preprints in February, but recently underwent peer review before being published as journals Science.org this week, one month after the World Health Organization recommended scientists continue researching the origins of the coronavirus.
One study included scientists from around the world using mapping tools and social media to conclude that, despite the "exact circumstances remain obscure," the virus was likely present in live animals sold at the Huanan Seafood Market in late 2019, just prior to the global pandemic.
The animals were held close together at the time, which would have made it easy for them to exchange germs, although the study didn't determine which animals may have been sick at the time.
Researchers involved in the study determined that the earliest confirmed COVID-19 cases were among vendors who sold the animals, as well as shoppers who attended the market, and that two separate viruses circulating in the animals were transmitted into humans.
The other study included researchers taking a molecular approach to determine that COVID likely started in a cross-species transmission between animals and humans. The researchers claimed that the first animal-to-human likely took place around November 18, 2019.
"These findings indicate that it is unlikely that SARS-CoV-2 circulated widely in humans prior to November 2019 and define the narrow window between when SARS-CoV-2 first jumped into humans and when the first cases of COVID-19 were reported," the study states. "As with other coronaviruses, SARS-CoV-2 emergence likely resulted from multiple zoonotic events."