Almost two years since the first case of COVID-19 was reported, scientists are still baffled by the actual origins of the virus that has tormented the world. Theories of its origins have been discussed at length like it emerged in the wild and jumped to humans. There were also speculations that it escaped from a Chinese laboratory.
But now, a growing number of scientists are trying to focus on the animal origins of the virus to further understand its nature and prepare for future viruses and variants.
Zoonotic Transmission More Likely Than Lab Leak
As the global death toll of COVID-19 surpasses, 5.2 million on its second anniversary, scientists are more convinced of the animal origins of the virus. Associated Press reported that many scientists regard animal-to-human transmission as a more plausible explanation of the spread of the virus.
Stephen Goldstein, a scientist from the University of Utah, said that even though the lab leak scenario gets more attention than the zoonotic transmission, most evidence points to the latter. He and 20 colleagues have published a study titled "The origins of SARS-CoV-2: A critical review " published in Cell Press, laying out the evidence of his claims.
Moreover, evolutionary biologist Michael Worobey from the University of Arizona said that he always thought zoonotic transmission was more likely than lab leak. Like Goldstein, Worobey and his colleagues are now even more confident about their theory on the virus having animal origins as more data has pointed to this theory.
Worobey said that the lab leak theory is a huge distraction taking the focus away from the real cause of the transmission. But others are not so sure about this statement. US President Joe Biden has ordered a review over the summer and showed that four US agencies believed with low confidence that the virus had an animal-to-human transmission path. While one agency believes it was from a lab leak.
According to the lab leak theory, the novel coronavirus was accidentally exposed due to inadequate practices in the lab while working on samples from the wild or when scientists were creating the virus. Although, US intelligence officers have already rejected suspicions that China might be making a bioweapon.
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Zoonotic Transmission of COVID-19
In Goldstein's study, he and his colleagues mapped the geographic locations of the first wave of COVID-19 cases in December 2019 when it first occurred. According to News Medical Life Sciences, cases first emerged close to the Huanan Seafood Wholesale Market in Wuhan, China, and other markets that have live animal trading.
After the first case was detected, more cases were reported, and it radiated outward geographically, followed by death cases in January 2020. Scientists said it was the second marker that the virus had already spread throughout the population.
The researchers noted that they found no evidence that the virus escaped from the Wuhan Institute of Virology, which was often cited as the source of the alleged lab leak. The laboratory was also marked on the map; since it is a distance away from the animal market where the first patient caught the virus, the theory remains questionable.
Scientists said that COVID-19 is not the first infectious disease with zoonotic origins, as previous viruses or outbreaks were also found to have come from live animals. For instance, the 2002 and 2003 SARS outbreaks were associated with living animals in China and the MERS-CoV that infected people in the Middle East and Africa.
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