Studies Find COVID-19 Outbreak Originated at Huanan Market in Wuhan

A pair of studies released last weekend found the COVID-19 pandemic was caused by at least 2 zoonotic transmission events at the Huanan Seafood Wholesale Market in Wuhan, China.

Scientific studies released over the weekend seem to confirm that COVID-19 was not the product of a lab leak. Instead, the 2 studies suggest the SARS-CoV-2 virus emerged at the Huanan Seafood Market in Wuhan, China of natural zoonotic origin.

Together, the studies found the geographical clustering of the earliest COVID-19 infections and proximity to live-animal vendors suggest the pandemic occurred at the Huanan Seafood Wholesale Market.

The investigators documented 2 separate occasions in late 2019 during which the virus likely transferred from the live mammals sold to humans working or shopping at the market.

Dr. Angela Rasmussen, an author of the study “The Huanan market was the epicenter of SARS-CoV-2 emergence,” commented via Twitter, “Despite complaints that there's no evidence supporting a natural zoonotic origin for SARS-CoV-2 vs a lab leak, some of us never stopped looking for evidence of either. Along with some amazing colleagues, we may have found it, at the Huanan Seafood Market.”

In Rasnussen’s study, the investigators used spatial analyses to demonstrate the first confirmed COVID-19 cases were centered around the market. They noted that collected SARS-CoV-2 environmental samples were directly linked to live animal vendors.

The other recent study, “SARS-CoV-2 emergence very likely resulted from at least two zoonotic events,” found that genomic diversity early in the coronavirus pandemic suggests the virus arose from repeated zoonotic events. The investigators identified that until February 2020, the coronavirus only consisted of 2 viral lineages, called A and B. Using novel phylodynamic rooting methods and epidemic simulations, they found the 2 lineages likely resulted from at least 2 distinct cross-species transmission events into people.

Together, the genetic coronavirus samples and geolocation analyses point to a section of the market where live animals were sold. Just as live animals markets sparked the severe acute respiratory syndrome (SARS) epidemic nearly a decade ago, these studies offer strong evidence that the COVID-19 pandemic was caused by zoonotic infection at the Huanan Seafood Wholesale Market.

The question of where and how the SARS-CoV-2 virus originated had sparked extensive debates. Though these studies offer convincing reports, some scientists want more evidence. No studies thus far have definitively proven what type of animal originally spread the virus to humans, though most speculate it may have been a raccoon dog, a mammal used for fur and food in China. Racoon dogs were sold in a part of the Huanan Market where positive SARS-CoV-2 samples were collected, and have previously been shown capable of carrying other types of coronaviruses.

These studies are preprints, and have not yet been published in a peer-reviewed journal.