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PARIS (AFP) – As many scientists scramble to find vaccines to control the spread of the coronavirus pandemic, other researchers are digging into the past, trying to unravel one of the virus’s biggest mysteries: exactly where it came from.
The World Health Organization (WHO) has assembled an international team of 10 scientists to trace the origins of the virus. They will have to investigate both the suspected animals and how the first patients may have been infected.
“We want to know the origin and we will do our best to know the origin,” WHO chief Tedros Adhanom Ghebreyesus told reporters on Monday (November 30).
But success is by no means assured.
The first cases were reported in the Chinese city of Wuhan a year ago, before countries around the world began registering increasing infections. The WHO said the first cases in Wuhan are believed to date from early December.
But “where an epidemic is first detected does not necessarily reflect where it started,” he added in a November report.
In recent months, researchers from several countries have suggested that the cases may have gone undetected long before December 2019, based on analysis of sewage or blood samples.
But there is a lack of “clear evidence” to back up these claims, said Dr. Etienne Simon-Loriere, from the department of virology at the Institut Pasteur in Paris.
To establish a family tree of viruses, researchers rely on genetic analysis. This can help “better understand the dynamics of transmission, particularly how the virus may have evolved over time and how clusters may be related in time and place,” the WHO said.
Jump to humans
Scientists agree that the disease has an animal origin.
“The big question is what led him to jump into humans,” Dr. Etienne Simon-Loriere told AFP. Suspicions have fallen on bats, which are “an important reservoir of coronavirus,” he adds.
But there probably would have been an intermediate animal to convert Sars-CoV-2 into people.
The pangolin, a mammal subject to rampant regional wildlife smuggling, was identified as a probable carrier early on based on genetic analysis. But the case is not solved.
The WHO researchers will need to clarify this point by investigating the wet market in Wuhan, which sold live and wild animals and has been linked to many of the early cases.
The team will be armed with clues that we did not have at the beginning of the pandemic.
Dr. Simon-Loriere said they could look for an animal with a virus receptor, a protein called ACE2, similar to that found in humans. It is through this receptor that the virus attaches itself to cells.
Some animals like minks and ferrets have been found to have a very similar receptor to humans, while others are quite different.
Another origin theory that swirled in conspiracy rumors for months was that the Wuhan Institute of Virology was involved in the outbreak.
In the context of diplomatic tensions, US President Donald Trump touted the idea, claiming that the virus could have leaked from the biosafety laboratory. China has rejected the accusations.
While Dr. Simon-Loriere said it was not yet possible to completely rule out the idea that the virus accidentally escaped, he stressed that “there was no indication that it was artificial.”
“All the elements of its genome have already been observed in nature, mainly in bat coronaviruses,” he said.
Unraveling the ‘riddle’
The WHO says that understanding how an epidemic started is “essential to prevent further introductions into the human population.” But he has cautioned that the process of tracking how a disease jumped out of animals “is a puzzle that can take years to solve.”
“The introduction of a new virus into the human population is one of the greatest mysteries that an epidemiologist can hope to unravel,” he said.
The goal is to “understand the mechanism and put measures in place to prevent the emergence of a new Sars-CoV-3, 4, etc.,” said Dr. Simon-Loriere.
For example, during the 2002 Sars epidemic, the ban on the consumption of civet cats, identified as intermediate hosts for that coronavirus, is credited with helping prevent reintroduction of the virus into humans.
The UN health agency sent an advance team to Beijing in July to lay the groundwork for the investigation. But it is unclear when the largest team will be able to travel to China to begin its work.
In late November, the WHO said it hoped to have a larger team of scientists on the ground “as soon as possible.”
The United States has accused Beijing of not being transparent, while saying the WHO bowed to China and was slow to investigate how the outbreak started. Others have expressed concern that the agency may have allowed China to dictate the terms of an international investigation into the origins of the virus.
Dr. Tedros told critics to stop “politicizing” the issue on Monday.
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