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The Wuhan Huanan Seafood Wholesale Market in China’s Hubei province is the focus of investigations into the origin of the Covid-19 pandemic. Illustration: SCMP

Exclusive | WHO’s coronavirus detectives look to Wuhan market as undisclosed map surfaces

  • A previously unpublished floor plan of the city’s Huanan market shows where people with the first recorded Covid-19 cases worked or shopped
  • This comes as the WHO investigates the source of the virus, which China says originated elsewhere, and pandemic politics sours US-China relations

This is the third story in a 15-part series on the Covid-19 disease, one year after it first emerged in the Chinese city of Wuhan. It takes a closer look at the Wuhan market, using a never-before-published floor plan of the sprawling facility used by the early investigators in China. Please support us on our mission to bring you quality journalism.

A sprawling seafood market in the Chinese city of Wuhan was the original ground zero for scientists looking to pinpoint where and how the virus that caused the Covid-19 pandemic first crossed into humans. One year on, the search is returning to that controversial site.

In December last year, as patients started showing up at Wuhan hospitals with unexplained pneumonia symptoms, doctors noted many had worked at the city’s Huanan Seafood Wholesale Market. Chinese officials later ruled out the market as the place where the virus first infected humans, citing medical investigations of the facilities.

But China has released sparse details about its studies of the market, which at the time employed more than 1,100 people at hundreds of food stalls over an area the size of about four soccer fields. Beside seafood and vegetables, it also sold varieties of wild animals.

A World Health Organization (WHO) investigation that kicked off in October will now look again at the market to try and reconstruct the outbreak, as Beijing promotes a view that the virus could have originated outside China. Researchers say the mission will need access to information that has not been made public about what was found at the market.

As the WHO embarks on its review, the South China Morning Post has obtained a never-before-published floor plan of the Huanan market used in those first investigations that provides a rare public glimpse into what took place.

The colour-coded plan, based on data collected by the Chinese Center for Disease Control and Prevention (CDC) in January, shows for the first time where some of the first infected people worked or shopped. It also shows which of the market’s 653 stalls turned up positive for the virus after swabs were taken by scientists. The floor plan was provided by a person familiar with the initial investigations, who declined to be identified because of concerns about repercussions.

LACK OF TRANSPARENCY

Using a Freedom of Information Act request in the US, the Post also obtained a separate map of the market held by the WHO and the US Centers for Disease Control. That map is blurred, but there are areas where markings by investigators differ between the versions. The market layout in both is almost identical.

While limited conclusions can be drawn from the plan itself, experts say it underscores the lack of transparency about what other information was gathered by scientists and investigators in China.

“The key thing is that it shows that they did do what, of course, the investigators would have done – they made a map … and it means there’s probably another map, a later, more detailed map,” said Daniel Lucey, a doctor and adjunct professor of infectious diseases at Georgetown University Medical Center in the US.

That could include the full scope of work at the market, where Chinese scientists took samples from hundreds of frozen animal carcasses and swabbed door-handles and sewage ducts. The extent of this work, more than 1,000 samples in total, was released by the WHO in November in a document outlining its investigation plan.

A slide from the US CDC that includes an illegible version of a floor plan used in investigations of the Wuhan Huanan Seafood Wholesale Market. Photo: Handout

According to the document, none of the frozen carcasses tested positive, while 69 of 842 environmental samples did. But beyond these numbers, little information is available about which animals were sampled and the extent of follow-up studies on humans and animals linked to the market. China has not disclosed if live animals were among those sampled.

A recount of where all the samples – positive and negative – were taken, paired with results from human and any live animal tests and the locations of animal species sold at the market, would “document the thoroughness of the investigation”, Lucey said. It would then point the way for further research into the virus’ origin, he said.

Such mapping is “part of the investigations needed to understand how the virus was transmitted”, said Nagi Shafik, a public health adviser and former head of the WHO office in Pyongyang, North Korea.

Shafik said investigators would also want to know where drainage and sewage systems ran, where the poultry and wild animals were brought from, and whether all visitors to the market were tracked down.

TRANSMISSION PATHWAYS

Scientists broadly agree the virus is likely to have come from a bat, before infecting humans via an intermediary animal and unleashing a pandemic that has so far claimed more than 1.6 million lives.

This transmission path is believed to be the route taken by Covid-19’s sister disease, severe acute respiratory syndrome (Sars), which broke out in 2002. It was linked by scientists to a bat virus circulating in live civet cats sold at markets similar to Huanan, in Guangdong province in southern China.

Wuhan’s market was linked to about two-thirds of the first 41 Covid-19 cases identified in the city, according to a study in The Lancet medical journal. As live animals such as bamboo rats, badgers and deer were sold in the market, it seemed a likely place for a pathogen to leap species.

Officials in full protective gear collect samples at the Huanan Seafood Market in Wuhan on January 22. Photo: Simon Song

But records published in the same article show that three of the first four Covid-19 patients had no evident ties to the market. This and a lack of genetic evidence linking the virus to animals in the market prompted a shift in focus to other potential transmission pathways.

In May, Gao Fu, director of the Chinese CDC, proclaimed the market was a “victim”, not the source of the outbreak.

While international experts agree that may be the case, the market still figures prominently in the WHO’s investigation as a critical link in the outbreak that could yet yield clues.

“We should also look again at the famous wholesale market where the first cases were detected, look at everything that went in and out of the market at that time, and try to find out where these products and animals … came from … the workers working in this market who got infected severely in December, where did they come from?” said Peter Ben Embarek, a WHO official familiar with the investigation plans, at a virtual question and answer session hosted by the UN health body on November 26.

Where did Covid-19 originate? These virus sleuths are assessing every theory

While the Post’s freedom of information request showed the WHO and the US CDC had a floor plan of the market by late January, it was not clear if the Chinese CDC plan obtained by the Post with different markings was shared with those health bodies.

A US CDC spokesperson referred questions about the floor plan obtained via the freedom of information request to the WHO.

Neither the WHO nor the US CDC responded to requests for comment about the other floor plan obtained by the Post. A spokesman for China’s National Health Commission (NHC) said it was not possible to comment without viewing the floor plan, and that there might have been multiple versions of such plans used by the Chinese CDC in January.

In a faxed response to the Post on Sunday evening, the NHC said: “In the process of investigation, disease control experts often make a schematic plan, and continue to adjust and update it as necessary.”

The NHC declined to share any versions of market plans used by the Chinese CDC, or any conclusions drawn from the investigation.

EPIDEMIOLOGICAL DETECTIVE WORK

The Chinese CDC map – which the source said was finalised around January 22-23 – shows the location of 33 stalls that were linked to 45 suspected and confirmed human infections, according to an accompanying description.

It is unclear why some cases would have remained “suspected” on a plan drawn up more than a week after Wuhan received diagnostic kits used to confirm infection.

The floor plan shows most stalls that had positive environmental samples were concentrated in two sections, one selling wildlife and poultry, and another selling seafood. Stalls with human cases appear broadly distributed across the market’s western side.

A man kills fish in a wet market in Wuchang, Wuhan city, central China's Hubei province, on January 5. Photo: Simon Song

“Seeing the precise location of the environmental samples is helpful and their locations next to human cases would tend to support these representing human infections sampled from the environment,” said Professor David Robertson, who is head of viral genomics and bioinformatics at the Centre for Virus Research at Scotland’s University of Glasgow.

Genetic sequences of the virus found at the market in January and shared by Chinese researchers indicate the pathogen found in the environment came from sick people, not animals, supporting the theory it may have spilled into humans elsewhere, and earlier.

Because the floor plan obtained by the Post includes clusters and “suspected” cases, it is impossible to use it to verify a recent statement from a top Chinese CDC official that cases were mainly concentrated in a section selling frozen seafood – a point raised to suggest the virus may have been imported on such products.

WHO wants end to ‘panic-then-forget’ approach to epidemics

While the floor plan appears to have been a first step toward epidemiological detective work, little is publicly known about further investigations or what resulted.

There was no “analytical epidemiological study among vendors and shoppers”, according to a document laying out the terms of reference for the current WHO mission into the origins of the virus.

“Without detailed mapping of exposure factors at the market over the exposure period, type of products and animals sold, the proportion of animals and commodities that were available for testing, interpreting laboratory sampling results remains difficult,” according to the document which was written in July during a visit by two WHO experts to China and released last month.

Some of this may be due to gaps in what information it was possible to gather.

NO RESULTS

Early accounts indicate the market was sanitised and cleared before scientists went in, although a May report in The Wall Street Journal said local officials collected samples from wild animals the day before the market was shut.

China has not said that any live wild animals from the market were tested, with only frozen animal carcasses referred to in the WHO mission’s terms of reference.

“The timing is important, because if it was already disinfected, if the animals were already removed, a lot of this key information would be lost already,” said Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations in the US.

The report from a joint WHO-China mission in February said investigations – including tracing back the animals sold at the market – were being undertaken. China has since said the subsequent investigations yielded no results.

“For almost a year we are asking ourselves, ‘does Covid-19 have a reservoir or an intermediary host?’. We worked so hard … we haven’t found anything,” Chinese CDC director Gao said at a scientific panel last month.

[China’s] failure to allow a full and independent investigation into the origins of the outbreak was a major failure of transparency and international cooperation
Lawrence Gostin, Georgetown University

In July, Wuhan Institute of Virology researcher Shi Zhengli told Science Magazine she was part of an official team of researchers who collected samples from farmed animals and livestock in Hubei province, where Wuhan is located, but found no positive tests for the virus.

It was not clear which animals were sampled and whether the investigations extended outside the province.

The first phase of the WHO mission will focus on Wuhan, and includes “mapping activities and items traded” at the market in late November and December, and their supply chains.

The WHO’s international team of 10 medical and veterinary experts is expected to join Chinese counterparts in the country to go over their research “as soon as possible”, according to the Geneva-based organisation. No specific dates have been provided.

Workers clean the Huanan market on January 4. Photo: Simon Song

PANDEMIC POLITICS

While the scientists conduct their research, pandemic politics has deeply soured relations between Beijing and Washington in what seemed a race to the bottom of unsubstantiated allegations and Twitter attacks. These ranged from the virus escaping from a Wuhan laboratory to the US military planting it in the city.

China has maintained that while the virus was first identified in China, it may not have originated there. It has also defended its record of sharing data.

“While making every effort to prevent and control the epidemic, the Chinese government insisted on openly and transparently releasing information. Since January 3, it has regularly reported the epidemic information to the WHO, relevant countries and regional organisations,” China’s NHC said in their faxed response to the Post on Sunday.

China rules on coronavirus testing for frozen meats give importers a chill

In recent weeks, China has suspended food imports from several countries after it said packaging tested positive for Covid-19. This has been linked to the recent suggestion that the pathogen originally entered Wuhan on packaging presumably contaminated by undetected, sick people outside China.

Infectious disease experts are sceptical of these claims, especially as the closest known relatives of Sars-CoV-2 – the coronavirus that causes Covid-19 – are found in bats in China and Southeast Asia.

At the same time, the WHO and researchers in several countries have said Sars-CoV-2 may well have come from outside China. The examples of HIV/Aids and other epidemics show the origin of a disease can be in a different place from where an outbreak is first identified.

But the WHO and others have also insisted Wuhan is the place to start the search, based on science, and because viruses do not care about politics – even as politics poisoned cooperation.

Coronavirus was on many continents before Wuhan outbreak, Chinese team says

In a different environment, the WHO could have used quiet diplomacy to convince Beijing to reveal more information, said Huang at the Council on Foreign Relations. “But all this becomes so politicised and this lack of trust makes this impossible,” he said.

Lawrence Gostin, director of the O’Neill Institute for National and Global Health Law at Georgetown University in the US, said “rapid and full access to the market” could have helped in the fight against the outbreak.

“China has done many things right with the Covid-19 response,” he said. “But its failure to allow a full and independent investigation into the origins of the outbreak was a major failure of transparency and international cooperation.”

This article appeared in the South China Morning Post print edition as: Mapping the outbreak
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