Tracing the virus's path is important to prevent future viral spills, but scientists say the World Health Organization team faces a daunting task.
November 15, 2020 Share on FacebookShare Share on TwitterTweet Share on WhatsAppShare
On November 5, the WHO quietly released details about its mission to China, which it describes as a global study of the origins of SARS-CoV-2 (REUTERS).
Ten months have passed since health officials cited Wuhan's Huanan Seafood Wholesale Market as the zero point of the COVID-19 pandemic, and for almost as long there has been a global debate about how the pandemic started. But the public will soon be able to learn the answers as the World Health Organization embarks on the final stages of a search for the origins of the coronavirus.
During a press conference on October 23, Michael Ryan, executive director of the WHO Health Emergencies Program , said that Chinese scientists have already started the first studies for the two-phase research. Based on what those experts find, WHO will then deploy an international team to China to collaborate with many of the country's leading scientists in tracing the roots of COVID-19. A week later, the director general of the organization, Tedros Adhanom Ghebreyesus, assured that a group of international experts had held a first virtual meeting with their Chinese counterparts, before pledging the full support of the WHO for the process. And on November 5, the WHO quietly released details about its mission to China, which it describes as a global study of the origins of SARS-CoV-2.
The months-long delay in launching this investigation has drawn criticism from public health researchers and world leaders, such as US President Donald Trump, who have accused the WHO of being too respectful of China's wishes. During the first phase of the search, a team from WHO will not be present for the field surveys and will only review and discuss the data collected by Chinese researchers. Some reports have described this arrangement as the responsibility given by the WHO, given that the organization is sponsored by individual nations and China is its second-largest donor after the United States.
But disease detectives who have worked on similar searches say this is the same. WHO is understaffed – with 7,000 employees in 150 countries – to carry out large-scale research on its own and always relies on national teams or international volunteers for field work.
“If you come in with a mindset of who is to blame, your opinion is different than wondering why it spread and what can we learn,” says Sian Griffiths, who co-chaired the Hong Kong government investigation into the SARS epidemic in 2003. The specialist emphasizes the need for objectivity in such a process: “Frankly, looking back and blaming is not very relevant.”
In 2003, a WHO team arrived in China almost three months after the initial case of the SARS coronavirus outbreak and were still able to identify the animal source within weeks. Such localization is possible long after the onset of disease thanks to genetic tracing , which has only become more advanced since then. That experience, and other past research, may reveal what the public should expect from this latest virus-hunting effort.
Hunting the host
Months of genetic research have already concluded that the pandemic began with what is known as a zoonotic overflow, an event in which a germ passes from an animal to humans (REUTERS)
WHO's Ryan said planning began in February, although the scope of the final mission was merged in July, when a two-person WHO team completed a three-week preliminary assignment: “We have been working with all the parties to bring together studies to better understand the origins of this virus. ” The project will include epidemiological studies of COVID-19 cases, biological and genetic analyzes and research in animal health.
WHO spokeswoman Margaret Harris maintains that this investigation into the origins of the pandemic could not have started earlier because the organization's first COVID-19 missions in China had to prioritize treating the effects of the virus on the human population. .
At the time, nothing took precedence over “how to treat it medically, what factors are helping it spread, what strategies are working to try to stop transmission,” Harris says . “We needed to learn very quickly what this virus was and what were the best ways to prevent disease and death.” Meanwhile, months of genetic research have already concluded that the pandemic began with what is known as a zoonotic overflow, an event in which a germ is passed from an animal to humans.
How this unfortunate leap can now be determined by using epidemiology and genetics to track “patient zero,” says Linfa Wang, a biologist and director of the Emerging Infectious Diseases Program at Duke-NUS School of Medicine in Singapore. Wang is colloquially known as “The Batman,” thanks to his pioneering research during SARS in 2003. The WHO recruited Wang during that mission to follow the human thread, and he traced the virus to an intermediate host called a civet cat. and then to bats.
For COVID-19, the most crucial part of this undertaking would involve testing biological samples, such as blood, that are routinely collected and stored in hospitals. The researchers would study samples from before and after the coronavirus outbreak was publicly declared at the end of December 2019. Ideally, this retrospective survey would be spread throughout China and neighboring countries.
“I would analyze stored human blood samples for antibodies to find out how long SARS-CoV-2 has been circulating in the human community and where it has been circulating,” explains Ian Lipkin, director of the Center for Infection and Immunity at the University of Columbia. whose team used this tactic to trace the MERS coronavirus to camels in the Middle East. (MERS emerged in 2012. It is a cousin of the novel SARS-CoV-2 coronavirus and the original SARS).
Researchers should evaluate travel history and contact with animals to identify which activities put people at higher risk of infection (REUTERS)
Of the 336 animals sampled at the Wuhan market, none tested positive for SARS-CoV-2. In contrast, 8 percent of environmental swabs, many related to sewage and sewage, carried the virus.
This test will help build an early timeline of COVID-19. Christine Johnson, an epidemiologist at the University of California at Davis, says key questions would include: “What behaviors and occupations did people initially exposed or infected have? Are people more likely to have interacted with certain animal species or traveled to specific places? “
Researchers must evaluate travel history and contact with animals, Wang says , to identify which activities put people at higher risk of infection. The surveys collect blood, urine, and feces samples from animals such as bats, pangolins, civet cats, or any other mammal found in markets, animal trade and supply chains, on farms, and in wild habitats. Then scientists can implement routine measures to detect infections. This includes polymerase chain reaction (PCR) tests, to detect the genetic signature of the virus, and antibody tests, which detect blood proteins that defend the body from viruses, indicating exposure. Some samples would also be brought to the lab to see if a viable virus can be grown, a sign of a contagious infection.
China's ability to conduct this research should not be underestimated, especially during COVID-19, warns Wang. “The scientific investment and infrastructure that exists today is very different from 2003, and Chinese scientists are capable of doing whatever the international team comes up with, ”he says. For example, the genetic sequencing of the current next generation accelerates the process.
Raina MacIntyre, an infectious disease expert and professor at the University of New South Wales in Australia, says Chinese scientists have already done significant research on the possible animal origins of the SARS-CoV-2 virus. China and other countries have contributed genetic sequences of the coronavirus collected from humans to a database to track the evolution of the germ. By comparing the entries, various research groups have concluded that the new coronavirus “probably comes from bats, perhaps through an intermediate host animal,” says MacIntyre.
The multitude of SARS-like viruses that horseshoe bats retain makes them the prime suspect in the origins of the current pandemic (REUTERS)
The multitude of SARS-like viruses that horseshoe bats retain makes them prime suspects for the origins of the current pandemic. And those nocturnal cave dwellers are not only found in China, but also in the neighboring countries of Myanmar, Laos, and Vietnam. “We need a WHO-sponsored international collaborative network, like the one we had in 2003, and we need to seriously consider research beyond China,” Wang said.
“To be absolutely frank, missions like this are more for the exchange of knowledge and ideas than for the field work of 'wet science'”, acknowledges the expert. By that, he means that the international experts involved review data findings, share information, exchange ideas, and collaborate.
The field work leading up to a WHO mission can be carried out by Chinese scientists who have all the necessary knowledge, funds and tools , says Wang. What's more, it is not uncommon for governments to limit outsiders in researching a country. pandemic. “I can't imagine the United States would invite Chinese scientists to collect and analyze samples,” Lipkin says .
And during the 2003 search for the SARS host in China, Wang recalls how “prior agreement was required for a specific agenda and itinerary for any WHO mission before the team could enter the nation.”
Too little, too late, still mysterious?
In 2003, a WHO team arrived in China almost three months after the initial case of the SARS coronavirus outbreak and was still able to identify the animal source within weeks (REUTERS)
Some experts fear that the new WHO project will find nothing useful because it has been almost a year since COVID-19 emerged. Yanzhong Huang, senior global health researcher at the Council on Foreign Relations, is concerned that key samples or evidence have been lost, noting that the Huanan market was reported to be drenched in disinfectants before scientists investigated the site.
But global viral outbreak expert Daniel Lucey says there are signs that China has already completed considerable groundwork. “Of course they would have,” says Lucey , who works at Georgetown University, because “it is in China's national interest to do research as quickly as possible, for the sake of public health.”
Lucey points to China's follow-up of the first confirmed pandemic patient through November 17, 2019. Then there was an investigation in January conducted by 29 Chinese researchers across a mix of institutions that examined how many early COVID-19 patients could be linked to the Wuhan wet market . Their results indicated that 14 of the first 41 cases were not exposed there.
Still, some mystery remains surrounding the initial studies at ground zero. The Chinese Center for Disease Control and Prevention said in late January that it had collected nearly 600 samples on the market, and Wuhan Institute of Virology virologist Shi Zhengli made public statements last summer about testing samples. soil, sewage and door handles on the market.
But new details of the WHO mission plan say nearly 1,200 specimens were collected from the Wuhan market, which had 653 vendors selling items ranging from shellfish and chipmunks to giant salamanders and sika deer. However, of the 336 animals sampled on the market, none tested positive for SARS-CoV-2. In contrast, 8 percent of environmental swabs, many related to sewage and sewage, carried the virus.
“As such, it is unclear whether the market was a source of contamination, acted as an amplifier of person-to-person transmission, or a combination of those factors,” the report's authors write. The report also points to a survey that found that 14 percent of domestic and stray cats in Wuhan tested positive for the virus. In the Netherlands, the coronavirus has plagued mink farms, and these furry mammals are also widely bred in China.
Some experts fear that the new WHO project will find nothing useful because it has been almost a year since COVID-19 emerged (AFP)
Why do environmental samples test positive while animals test negative? In January, Lipkin from Columbia University visited China to share his experience, which included a meeting with George Gao, head of the Chinese CDC. Gao said at the time that the Huanan seafood market had been cleaned and its animals removed prior to sample collection, Lipkin recalled in an email exchange with National Geographic.
“This prevents the collection of blood that could be used to detect antibodies that would persist even if the virus was no longer present,” he says. “Antibody tests have an advantage in their ability to detect evidence of exposure regardless of whether the virus has been killed.”
The expert adds that although the search could begin in Wuhan, it is very likely that it will expand throughout the Hubei province, and “we would not be surprised if we knew that it was in humans before the Wuhan outbreak was detected in 2019.”
Wang places another goal above all else. For him, the key is for Chinese scientists and officials to have an open discussion with the WHO team, adding that research on the origins of the virus is so politicized that any conversation about such missions now “is symbolic until the issue is resolved. politics”.
The best step, says Wang , would be “to discuss the origin in a totally apolitical environment and with an open mind, recognizing that viruses related to SARS-CoV-2 probably exist in bats outside of China.”
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