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For Opinion 
1 hour ago
Dominic dwyer
Sydney – As I write, I am in hotel quarantine in Sydney, after returning from Wuhan, China. There, I was the Australian representative in the World Health Organization (WHO) research on the origins of the SARS-CoV-2 virus.
Much has been made of the politics surrounding the mission to investigate the viral origins of COVID-19. That is why it is easy to forget that there are real people behind these investigations.
As part of the mission, we met the man who, on December 8, 2019, was the first confirmed case of COVID-19; since then he has recovered. We met the husband of a doctor who died of COVID-19 and left behind a small child. We met the doctors working in the Wuhan hospitals treating those first cases of COVID-19 and we learned what happened to them and their colleagues.
We witnessed the impact of COVID-19 on many affected people and communities so early in the pandemic, when we didn’t know much about the virus, how it spreads, how to treat COVID-19, or its impacts.
We spoke with our Chinese counterparts (scientists, epidemiologists, doctors) during the four weeks that the WHO mission was in China. We met with them for up to 15 hours a day, so we became colleagues, even friends. This allowed us to build respect and trust in a way that you might not necessarily be able to do via Zoom or email.
This is what we learned about the origins of SARS-CoV-2.
It was in Wuhan, central China, that the virus, now called SARS-CoV-2, emerged in December 2019, triggering the largest infectious disease outbreak since the 1918-19 influenza pandemic.
Our investigations concluded that the virus was most likely of animal origin. It probably passed to humans from bats, through a still unknown intermediary animal, in an unknown location. These “zoonotic” diseases have triggered pandemics before. But we are still working to confirm the exact chain of events that led to the current pandemic. Sampling of bats in Hubei province and wildlife in China has not revealed any SARS-CoV-2 to date.
We visited the now-closed Wuhan wet market, which, in the early days of the pandemic, was blamed as the source of the virus. Some market stalls sold “domesticated” wildlife products. These are animals raised for food, such as bamboo rats, civets, and ferret badgers. There is also evidence that some domestic wild animals may be susceptible to SARS-CoV-2. However, none of the animal products sampled after the market closed tested positive for SARS-CoV-2.
We also know that not all of those first 174 early COVID-19 cases visited the market, including the man who was diagnosed in December 2019 with the earliest onset date.
However, when we visit the closed market, it is easy to see how an infection could have spread there. When it was open, they would have visited around 10,000 people a day, very close, with little ventilation and drainage.
There is also genetic evidence generated during the mission for a transmission group there. The viral sequences of several of the market cases were identical, suggesting a transmission group. However, there was some diversity in other viral sequences, implying other unknown or unsampled transmission chains.
A summary of modeling studies from the time to the most recent common ancestor of the SARS-CoV-2 sequences estimated the onset of the pandemic between mid-November and early December. There are also publications that suggest the circulation of SARS-CoV-2 in several countries before the first case in Wuhan, although they require confirmation.
The market in Wuhan, in the end, was more of an amplifying event than necessarily a true ground zero. Therefore, we must look elsewhere for viral origins.
Then there was the “cold chain” hypothesis. This is the idea that the virus could have originated elsewhere through growing, capturing, processing, transporting, refrigerating, or freezing food. Was that food ice cream, fish, bushmeat? We do not know. It is not proven that this triggered the origin of the virus itself. But to what extent did it contribute to its spread? Again, we don’t know.
Several “cold chain” products present in the Wuhan market were not tested for the virus. Environmental sampling in the market showed viral contamination of the surface. This may indicate the introduction of SARS-CoV-2 through infected people or contaminated animal products and “cold chain” products. Research on the products of the “cold chain” and survival of the virus at low temperatures is still ongoing.
The most politically sensitive option we looked at was the virus leaking from a laboratory. We concluded that this was extremely unlikely.
We visited the Wuhan Institute of Virology, which is an impressive research facility and appears to be well run, with due respect for the health of the staff.
We spoke to scientists there. We heard that the scientists’ blood samples, which are routinely collected and stored, were tested for signs of infection. No evidence of antibodies to the coronavirus was found. We analyze your biosecurity audits. No evidence.
We looked at the virus closest to the SARS-CoV-2 they were working on, the RaTG13 virus, which had been detected in caves in southern China, where some miners had died seven years earlier.
But all the scientists had was a genetic sequence for this virus. They had failed to cultivate it in culture. While viruses certainly escape the labs, this is rare. So, we came to the conclusion that it was extremely unlikely that this would have happened in Wuhan.
When I say “we”, the mission was a joint exercise between WHO and the Chinese health commission. In total, there were 17 Chinese and 10 international experts, plus seven other experts and support staff from various agencies. We look at clinical epidemiology (how COVID-19 spread between people), molecular epidemiology (the genetic makeup of the virus and its spread), and the role of animals and the environment.
The clinical epidemiology group alone examined China’s records of 76,000 episodes from more than 200 institutions of anything that might look like COVID-19, such as influenza-like illnesses, pneumonia, and other respiratory illnesses. They found no clear evidence of a substantial circulation of COVID-19 in Wuhan during the latter part of 2019 before the first case.
Our mission in China was only phase one. We must publish our official report in the next few weeks. Researchers will also look further for data, to investigate evidence that the virus was circulating in Europe, for example in early 2019. Researchers will continue to analyze wildlife and other animals in the region for signs of the virus. And we will continue to learn from our experiences to improve the way we investigate the next pandemic.
Regardless of the origin of the virus, people with the disease are at the beginning of the points, sequences and numbers of epidemiological data. The long-term physical and psychological effects, tragedy and anxiety, will be felt in Wuhan and elsewhere for decades to come.
* Dominic Dwyer is Director of Public Health Pathology, NSW Health Pathology, Westmead Hospital and University of Sydney, University of Sydney.
** Opinions expressed here are not necessarily those of the IOL.
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