In order to prevent future pandemics, it is important to understand the circumstances that led to past ones. This includes looking at all hypotheses in detail and trying to discern the origin from a complex array of data. Did the COVID-19 outbreak originate at a market in Wuhan, China, or escape from a lab known for researching coronaviruses? 

Two new research papers offer the strongest evidence, to date, of an animal origin. Photographic evidence (of wild animals such as raccoon dogs and a red fox) and genetic data are pinpointing a specific stall in the market from which SARS-CoV-2 could have originated, passing from animal to human. The caged animals were near a stall where scientists found the SARS-CoV-2 virus on a number of surfaces, including on cages, carts and machines that process animals after they are slaughtered at the market. Check out the paper and the imagery here. 

A separate study, focused on genetics, estimates the time, within weeks, of two “spillovers” of the coronavirus from animals to people.  The timing of the earliest known coronavirus infections coincides almost exactly with the timing of the outbreak at the seafood market, which began in early December. Access that paper here.

Dr. Michael Worobey, an evolutionary biologist who has dedicated his career to studying origins of pandemics (e.g., including the 1918 flu) and lead author of one of the papers, originally called for an investigation into the lab-leak hypothesis. Through scientific investigation, he found the data pointing to an animal origin instead. A key piece was the almost simultaneous emergence of two lineages of SARS-CoV-2. This challenges the lab-origin hypothesis, as it would require two different viruses leaking at roughly the same time.

Worobey makes an interesting point even if scientists were able to pinpoint exactly from which animal the virus originated (which they haven’t been able to do yet): “With the way that people have been able to just push aside any and all evidence that points away from a lab leak, I do fear that even if there were evidence from one of these samples that was full of red fox DNA and SARS-CoV-2 that people might say, ‘We still think it actually came from the handler of that red fox.”

Last week’s Science Wednesday is all about the age of misinformation and the denial of science, even in the face of strong evidence. Wishful thinking and denial is simply easier for many people – and fighting that will remain a challenge for scientists and science communicators for years to come. Skepticism is important, but so long as it’s based on actual facts and evidence. 

photo: Ulyana Horodyskyj, COVID plush