In the three years since the COVID-19 pandemic began, one of the most persistent questions has been how the virus that caused it—SARS-CoV2—first jumped from animals to humans. SARS-CoV2 is one of a group of viruses known as coronaviruses, commonly found in bats. But bats are rarely found in the Chinese city of Wuhan, where the virus emerged in December 2019. So how did the infection get into humans? Two theories have emerged: the “zoonotic” hypothesis, whose proponents argue that the virus jumped from animals to humans at a market in Wuhan; and the “lab leak” theory, according to which the virus escaped from a laboratory in the city. which one is correct?
The initial epicenter of the Covid outbreak appears to have been in Wuhan Huanan Seafood Wholesale Market, At first it seemed that the virus was transmitted from bats to humans through an “intermediate” animal that was infected outside the city and then sold in the market. This is how SARS first emerged 20 years ago. Researchers in 2021 confirmed that live animals, as well as fish and meat, were sold at the market in November 2019, when the first infection may have occurred. A new report from an international group of scientists on 20 March – based on analysis of the genetic sequence of samples taken by Chinese researchers from the market in January 2020 – shows the presence of animals such as raccoon dogs, weasels, foxes, elephants, porcupines and bamboo rats Confirmed. The raccoon dog, which can carry and transmit this virus, deserves special attention. But there is no way to prove from the available data that these animals transmitted SARS-CoV2 to humans.
A second theory emerged in the months following the outbreak. scientific on Wuhan Institute of Virology, a global center for coronavirus research, were working on genetic engineering of these viruses. Some observers thought that workers handling infected research animals may have provided a route for the virus to the outside world. The Chinese government has denied that the virus came from one of the country’s laboratories.
China’s reluctance to disclose information has complicated understanding of what really happened in the early days of the COVID outbreak. The genetic sequences used in the recent report on market animals were only temporarily placed on public databases. (They may be reissued when a revised version of the paper is published.) An early pre-print suggested that the virus may have already reached humans and that the market, rather than being the site of the initial infection, may have facilitated its spread. Has accelerated.
Despite the new data, the World Health Organization (WHO) said in a briefing on 17 March that both the zoonosis and lab-leak theories remained on the table. WHO epidemiologist Maria Van Kerkhove said the data was an “additional clue” in the search for the intermediate host.
Not everyone is convinced. The FBI had concluded some time ago that the epidemic was probably the result of a lab leak, saying it had “moderate confidence” in that assessment. In February the US Department of Energy—which has expertise on biological threats—came to the same conclusion with “low confidence”. Other US agencies support the zoonosis theory, or have been unable to make a decision. may have access to information that scientists haven’t seen, but that imbalance must be remedied soon. On March 20, President Joe Biden called for public information about the origins of Covid-19 held by intelligence agencies. signed a bill for
The need to identify the origin of the virus goes beyond its imperative to understand what is causing the estimated deaths 20m people, If Covid emerged from a lab, questions would arise about it protection of its research practices. But if the virus was zoonotic spillover in a market, scientists would need a better understanding of where and how these viruses emerged. This is exactly the kind of research that these laboratories in Wuhan do.
© 2023, The Economist Newspaper Limited. All rights reserved. From The Economist, published under license. Original content can be found at www.economist.com
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