Where did COVID-19 originate? Yahoo News Explains

More than a year after the outbreak of the coronavirus pandemic in Wuhan, China, the origins of SARS-CoV-2, the virus that causes COVID-19, remains a mystery. So far, scientists have not been able to pinpoint where and when the virus originated, but Yahoo News explores a few leading theories.

Video Transcript

- Did the coronavirus leak from the Institute of Virology in Wuhan, China?

- President Biden is calling on the intelligence community to step up its efforts to figure out the origins of COVID-19.

- More than a year after the outbreak of the coronavirus pandemic in Wuhan, China, the origins of SARS-CoV-2, the virus that causes COVID-19, remains a mystery. So far, scientists have not been able to pinpoint where and when the virus originated. But here are a few leading theories. All available evidence for COVID-19 suggests that it is a zoonotic disease, meaning that it crossed over from an animal species to humans.

To help identify the animal source of the virus and how it spread to humans, the World Health Organization assembled a team of 17 international scientists, including one from the US, to investigate. They traveled early this year to China to look into four possible scenarios for how the virus might have jumped to human beings. One scenario, which the WHO team ranked as possible to likely, is that the virus started in an animal, possibly a bat, that came into contact with a human.

Bats are thought to be a likely origin of the virus, because they were identified as the source of two previous coronaviruses that caused lethal outbreaks in the past decade. Severe Acute Respiratory Syndrome, SARS, and Middle Eastern Respiratory Syndrome, MERS. Coronaviruses sharing genetic characteristics with SARS-CoV-2 have also been found in bat species. However, scientists have yet to find any specific bat virus that would provide the missing link from the coronaviruses identified in bats in SARS-CoV-2 itself.

Another scenario the WHO researchers ranked as likely to very likely is that the virus traveled from another animal species to humans, possibly a mink or a pangolin, a scaly ant-eating mammal. The theory is plausible, because humans are more likely to be in contact with those species in China than they are with bats, particularly if they're being raised on a farm or sold in wildlife markets.

Wildlife trade and consumption was legal in China before February 2020. The Chinese government decided to ban the consumption of almost all wild animals shortly after a number of suspected COVID-19 cases were traced back to the Hunan Seafood Market in Wuhan last December. A menu from the market, which circulated online last year, showed that more than 100 species of wild animals were sold as food there.

This is why, initially, scientists suspected that one of these animals could have been responsible for passing the virus to humans. However, today, they are not so sure about the role the market played in the initial outbreak. That's because 13 of the first 41 hospitalized patients with COVID-19, including the first documented case, had no link to the seafood marketplace. And to this day, scientists have no clue where this early case got infected.

Another theory embraced by the Chinese government is that the virus was introduced via the food chain by contaminated food or packaging, particularly frozen and refrigerated foods. This scenario makes it possible that the virus may not have originated in China, but was imported from elsewhere instead. Although researchers have found evidence that suggests that pathogens such as the novel coronavirus can, aided by cold temperatures along a supply chain, survive longer, scientists say there's little reason to believe that imported foods could be the source of the pandemic.

The WHO investigation, however, ranked this theory as possible. The final theory, which has recently gained renewed traction, is the possibility that Chinese scientists studying coronaviruses in Wuhan may have accidentally allowed the virus to escape the lab. Recent reports about inadequate safety at the Wuhan Institute of Virology, where risky studies on coronaviruses from bats were conducted before the pandemic, have made the lab leak scenario more compelling than previously thought.

The WHO report categorized this theory as extremely unlikely. But scientists worldwide have said the WHO team lacked access to crucial data that was needed to conduct a thorough investigation. Scientists and government officials worldwide have expressed concern about the lack of transparency and cooperation from the Chinese government. They, including President Biden, are now calling for additional investigation into the origins of the virus, including the lab leak scenario.

Last week, President Biden requested US intelligence agencies to conduct their own investigation. And they are expected to report their findings in approximately three months. Hopefully, this effort will be able to shed some light on how the virus got started. Experts say this information is crucial to prevent future pandemics from happening.

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