The mystery still shrouds the origin of COVID-19

While many scientists are racing in search of vaccines to tame 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 has assembled an international team of 10 scientists to trace the origins of the virus.

They will have to investigate both the suspicious animals and how the first patients may have been infected.

“We want to know the origin and we will do everything to know the origin,” WHO chief Tedros Adhanom Ghebreyesus told reporters on Monday.

But success is by no means guaranteed.

Source of the diffusion

The first cases were reported in the Chinese city of Wuhan a year ago, before countries around the world started experiencing escalating infections.

WHO said the first cases in Wuhan are believed to date back to early December.

But “where an outbreak is first detected does not necessarily reflect where it started,” he added in a November report.

In recent months, researchers from various countries have suggested that the cases may have gone unnoticed long before December 2019, based on analysis of wastewater or blood samples.

But there is a lack of “clear evidence” to support these claims, said Etienne Simon-Loriere, of the virology department 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 the clusters might be related over time and place,” WHO said.

Jump to the humans

Scientists agree that the disease has an animal origin.

“The big question is what caused her to jump into humans,” Etienne Simon-Loriere told AFP.

Suspicions have fallen on bats, which are “an important reservoir for coronaviruses,” he adds.

But there probably would have been an intermediate animal to feed SARS-CoV-2 in people.

The pangolin, a mammal subject to rampant regional wild animal smuggling, has been identified as a probable vector based on genetic analysis. But the case is not solved.

WHO investigators will need to clarify this point by probing the Wuhan wet market, which sold live and wild animals and has been linked to many early cases.

The team will be armed with clues we didn’t have at the start of the pandemic.

Simon-Loriere said they could look for an animal with a receptor for the virus, a protein called ACE2, similar to that found in humans.

It is through this receptor that the virus attaches itself to cells.

Some animals such as minks and ferrets have been found to have a receptor very similar to that of 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.

Against the backdrop of diplomatic tensions, US President Donald Trump touted the idea, claiming the virus may have leaked from the biosecurity lab.

China denied the allegations.

While Simon-Loriere said it was not yet possible to completely rule out the idea that the virus had accidentally escaped, he pointed out that “there was no indication that it was man-made”.

“All the elements of its genome have already been observed in nature, mainly in bat coronaviruses,” he said.

Unravel the riddle

The WHO says understanding how an epidemic started is “essential to prevent further introductions to the human population.”

But he cautioned that the process of tracking how a disease jumped from animals “is a conundrum that can take years to solve.”

“The introduction of a new virus into the human population is one of the greatest mysteries an epidemiologist can hope to unravel,” he said.

The goal is “to understand the mechanism and put measures in place to avoid the emergence of a new SARS-CoV-3, 4, etc.”, Simon-Loriere said.

For example, during the 2002 SARS outbreak, the ban on the consumption of civet – identified as an intermediate host of that coronavirus – is credited with helping to prevent reintroduction of the virus in humans.

The UN health agency sent an advanced team to Beijing in July to lay the groundwork for the investigation.

But it is unclear when the larger team will be able to travel to China to begin their work.

In late November, WHO said it hoped to have a larger team of scientists in the field “as soon as possible”.

The US has accused Beijing of not being transparent, while it says the WHO has bowed to China and dragged its feet into investigating how the outbreak began.

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.

Tedros told critics on Monday to stop “politicizing” the issue.

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© 2020 AFP