New studies find confirmation that the SARS-CoV-2 coronavirus that causes COVID-19 first spread from animals to humans at a market in Wuhan
Researchers agree that the coronavirus that causes COVID-19, SARS-CoV-2, likely first spread from animals to humans in two separate transmission events at a market in Wuhan in late November 2019.
The analyzes carried out were mainly based on the location of cases and environmental samples, as well as the genomic sequences of the SARS-CoV-2 isolates, from the first weeks of the pandemic in China.
Analysis of the available evidence strongly suggests that the pandemic arose from early human infections of animals for sale at the Huanan seafood wholesale market in late November 2019. This research is published in the prestigious journal Science.
The first cases clustered around the Huanan market in Wuhan.
In the first analysis, the researchers examined the geographic pattern of COVID-19 cases in the first month of the outbreak, December 2019. Thus, they were able to determine the location of 155 of the 174 COVID-19 cases identified by the World Health Organization. that month.
Their analysis showed that these cases clustered heavily around the Huanan market, while subsequent cases were widely dispersed in Wuhan, a megacity of 11 million people.
A surprising hallmark was that the first patients with COVID-19 without a history of having recently visited the market resided significantly more about, by medium term, than the patients who had visited it, which demonstrates the close relationship between the first cases and the Marketplace.
The researchers also determined that mammals now known to be infectious with SARS-CoV-2, including red foxes, badgers and raccoons, were being sold live at the Huanan market in the weeks prior to the first cases of infection.
The live animal market
Scientists produced a detailed map of the market and showed that SARS-CoV-2 positive samples reported by Chinese researchers in early 2020 showed a clear association with the western part of the market, where live or freshly slaughtered animals were sold in late 2020. 2020. of 2019.
The analysis showed that the market was also the initial epicenter and probably the place of appearance. Inside the second studythe researchers combined epidemic modeling with analysis of the early evolution of the virus from the first sampled genomes.
They found that the pandemic, which initially included two subtly distinct strains of SARS-CoV-2, likely arose from at least two separate human infections by animals at the Huanan market in late November 2019.
The analyzes also suggest that, during this period, there were many other animal-to-human transmissions on the market that, however, did not manifest in the recorded cases of COVID-19.
According to the researchers, the two studies collectively demonstrate that SARS-CoV-2, like SARS-CoV-1 before it, originated through animal-to-human jumps, in this case from animals being sold in a specific market in Wuhan, likely after transmission to these animals from coronavirus-carrying bats in the wild or on farms in China.
REFERENCES
The Huanan Seafood Wholesale Market in Wuhan Was the Initial Epicenter of the COVID-19 Pandemic
The molecular epidemiology of multiple zoonotic origins of SARS-CoV-2
