Origins of Covid-19: First human cases point to Wuhan market as source of coronavirus – Community News
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Origins of Covid-19: First human cases point to Wuhan market as source of coronavirus

A fresh look at what we know about the first cases of Covid-19 shows that the earliest known case occurred in a person who worked at the Huanan Market in Wuhan, who was suspected to be the source from the beginning of the pandemic

Health


Nov 18, 2021

2E2FJMB Photo taken on January 14, 2021, shows the Huanan Seafood Market in Wuhan, China, where many people were infected with the novel coronavirus in the early stages of the pandemic.  (Kyodo)==Kyodo Photo via Credit: Newscom/Alamy Live News

A sign pointing to the Huanan Market in Wuhan, China, where people were infected with the coronavirus in the early stages of the covid-19 pandemic

BJ Warnick/Newscom/Alamy

An analysis of what we know about the earliest cases of Covid-19 has strengthened the case that the coronavirus pandemic began when animals at the Huanan Market in Wuhan, China, passed the virus to humans. It concludes, among other things, that the first case involved a woman who worked as a fish seller on the market on 11 December 2019 and became ill.

It is clear that the SARS-CoV-2 virus is derived from bat coronaviruses. What’s not clear is where, when, and how it got from bats into humans. From the beginning, it was suspected that live animals in the Huanan market could be the intermediate hosts, as the first cases clustered around this market.

A World Health Organization report on the origin of SARS-Cov2 published earlier this year states that the first person known to have Covid became ill on December 8 and had no connection to the market. This was partly the reason why the report concluded that no firm conclusion could be drawn about the role of the market.

However, this man — a 41-year-old accountant who lives 30 miles from the market — went to the hospital with dental problems on Dec. 8 and didn’t develop Covid-19 symptoms until Dec. 16, Michael Worobey of the University of Arizona said in his analysis.

These data are corroborated by media interviews with the accountant, hospital records and a scientific article, Worobey says. That means the earliest known cases were indeed market-related, with the fishmonger falling ill on December 11.

It is unclear why this is not in the WHO report, as the team did speak with the accountant. “My guess is they were told this was the ‘December 8’ patient and just accepted it as read,” Worobey says. “But it would certainly be interesting to learn more about that interview.”

When asked whether their report was wrong, a WHO spokesperson said it was difficult to comment on certain cases. “The team did meet some early patients, but those were not epidemiological interviews that collected health data that would put them in the timeline,” the spokesperson said. new scientist. “Those interviews were done in 2020 by Chinese authorities.”

In total, a third of the 168 retrospectively identified cases in December were linked to the Huanan market, according to the WHO report. This is in line with what you would expect if the market were the source, Worobey says. Because the original SARS-CoV-2 virus was highly contagious and could spread asymptomatically, many cases would soon have no direct link to its source.

However, it has been suggested that this apparently strong link to the market is due to bias, as once the authorities were alerted on December 29, they specifically looked into things related to the market.

Worobey says this can be verified by looking at what happened in the three hospitals where doctors first realized something wasn’t right. They had identified 19 unexplained cases of pneumonia, ten of which were market-related, before higher authorities were alerted.

“There was a real preponderance of early covid-19 cases associated with the Huanan market,” he writes.

In addition, not only are many early cases linked to the market, they are specifically linked to the western part of the market where live animals such as raccoon dogs were housed. Raccoon dogs are a potential intermediate host – they can be infected with SARS-CoV-2 but show few symptoms.

“Combined, this is compelling evidence that Covid-19 has a live animal-associated market origin, as did the first SARS virus,” said David Robertson of the University of Glasgow, UK. “Whether the first transfers were from animals to customers in the market, through suppliers or both, is hard to say.”

Not everyone agrees. “There is nothing new in this article that could make a natural origin of SARS-CoV-2 more likely than a laboratory one,” said Rossana Segreto of the University of Innsbruck in Austria.

But other recent findings have weakened the argument for lab origins, which some researchers say was never strong. In particular, coronaviruses closest to SARS-CoV-2 found to date in bats in Laos have been identified. These wild viruses share traits in common with SARS-CoV-2 that some have argued could only have arisen in a lab during so-called gain-of-function experiments, showing that these traits can and do evolve in the wild.

Reference magazine: Science, DOI: 10.1126/science.abm4454

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