Study says Covid likely originated from Huanan market wildlife

The origin of the Sars-CoV-2 virus, which caused the Covid-19 outbreak that disrupted life across the world for nearly three years from January 2020, has been a topic of contention. While the Huanan seafood market in Wuhan, China, was in the centre of the storm during the initial months, later on an alternative suggestion emerged that the virus escaped from the Wuhan Institute of Virology, where staff were known to be studying bat coronaviruses, but not Sars-CoV-2.However, a new study by an international team concludes ‘beyond reasonable doubt’ that it is more likely that the virus emerged from wild animals sold at the market and not from a lab escape. The researchers re-analysed data from 800 samples collected at the Huanan market by the Chinese Center for Disease Control and Prevention beginning on January 1, 2020, and also studied viral genomes from the earliest Covid-19 cases. The Chinese government made the market data available in 2022, fully allowing scientists to conduct an in-depth study of the market-origin hypothesis. The results were published in the journal Cell last Thursday.Team member Ed Holmes at the University of Sydney said Chinese investigators swabbed surfaces, freezers, drains and cages to test for the presence of Sars-CoV-2. "We analysed these data to determine which species were present and where they were found in the market, particularly in relation to where Sars-CoV-2 was found,” he said. An analysis of genetic samples taken from the Huanan seafood market has identified a shortlist of wild animals being sold there that were the most likely source of the virus that sparked the Covid-19 pandemic.While bats are thought to have been the original carrier of the Sars-CoV-2 virus, it has been previously proposed that an intermediate wild species became infected and brought it to the market, where an outbreak in humans began. Stalls there sold live animals as well as seafood. The team found evidence for a variety of wildlife being sold at the market that could have been an intermediate host for the virus, including common raccoon dogs, masked palm civets and hoary bamboo rats. Importantly, traces of these animals were found in exactly the same stalls as Sars-CoV-2, said Holmes. "This suggests – but does not prove – that the animals were infected. Hence, it is very likely that Sars-CoV-2 emerged in a live animal market. All the scientific data point one way — to Sars-CoV-2’s natural zoonotic origin in the Huanan market, Wuhan,” stated Holmes.The genetic studies of the virus in the earliest Covid-19 cases revealed that few, if any, people were infected prior to the market outbreak, the team reported. However, it couldn’t rule out the possibility that the virus was brought to the market by an infected person handling animals. Team member Zach Hensel at NOVA University Lisbon, Portugal, said the study highlights the preventable risks posed by the human-wildlife interface in Huanan market, and the need to mitigate these risks in similar locations."Even though humans were, of course, everywhere in Huanan market and live mammals were concentrated in a small number of stalls, human viruses, other than Sars2, were rare and several animal viruses were quite abundant,” says Hensel. "This included one influenza virus with zoonotic spillover potential and an animal virus closely related to others that had caused devastating animal outbreaks.” He was of the view that simple personal protective equipment recommended for such settings prior to the outbreak of Covid-19 could have prevented the entire pandemic.