A statement from the American Association for the Advancement of Science (AAAS), which publishes the journal Science, says the scientists who compiled the studies concluded that SARS-CoV-2, the coronavirus that causes COVID-19, was likely to exist in live mammals sold at Huanan Seafood Wholesale Market in late 2019 before infecting humans. They say future studies should focus on where the wild mammals sold in Huanan come from, which could help prevent the risk of future pandemics. “Despite the observation that the prevalence of the earliest known cases of COVID-19 — reported from hospitals in Wuhan in December 2019 — was linked to the Huanan market, this did not establish activities in the Huanan market as the trigger for the pandemic,” AAAS states. the statement. The studies come after an expert panel drawn up by the World Health Organization said in June that more research is needed to determine how COVID-19 first started, including the possibility of a lab accident. Preprint or non-reviewed versions of the studies were released in February. In one, researchers used mapping tools to calculate the longitudes and latitudes of more than 150 of the first cases reported since December 2019, including those that had no appreciable direct market connections. They say the highest density of cases has been concentrated in the Wuhan market. The researchers also mapped cases from January and February 2020 using a channel on the Chinese social media app Weibo created for people who had COVID-19 and sought medical help. Using this data, they found cases in other parts of central Wuhan that came from the market. They say live mammals susceptible to SARS-CoV-2, including red foxes, pig badgers and common raccoon dogs, were also sold live on the market in late 2019. The researchers note that while they were able to retrieve location data for most of the December 2019 COVID-19 cases, exact longitudes and latitudes were not available for all of them. There is also no direct evidence that an intermediate animal was infected with early SARS-CoV-2 either at the Huanan market or elsewhere in its supply chain, such as on a farm, they say. In the second study, the researchers examined the genetic diversity of early SARS-CoV-2, identifying two lineages, A and B. Scientists say only the B lineage was found in 11 sequenced genomes of people directly linked to the Huanan market. Individuals with lineage A genomes, meanwhile, had no known contact with the market, but lived or lived nearby. Scientists believe both lineages circulated in non-human mammals, with the B lineage first appearing in humans probably in mid-November 2019, followed by the A lineage within days or weeks. As in the previous study, the researchers say they have no direct evidence of a virus, closely related to SARS-CoV-2, present in non-human mammals in the market or its supply chain.
