The TLDR: After months of negotiations with Beijing, a World Health Organisation team has landed in China to trace the source of the pandemic—which has long become fodder for an international blame game. We explain exactly what the team will look for and why its success matters.

The WHO mission

Ten international members—who include experts in virology, ecology and public health—have landed in Wuhan, where the first Covid case was detected. Their task: to pinpoint the species in which this virus emerged—and the circumstances in which it jumped from animals to humans:

Not on the agenda: assigning blame on any one country. As WHO officials say:

"We are looking for the answers here that may save us in the future, not culprits and not people to blame. We can blame climate change, we can blame policy decisions made 30 years ago. If you're looking for someone to blame, you can find people to blame on every level of what we're doing on this planet."

Why this mission matters: According to virologists, "The more we understand about how diseases emerge, the better we can predict and control them”—and change our behaviour to prevent further such outbreaks.

The plan: 

• Their efforts will focus on the Huanan Seafood Market—the site of the original cluster of cases—and the Wuhan Institute of Virology, which has meticulously documented this coronavirus, and its predecessors. 
• In the first phase, the WHO team will rely on their Chinese counterparts to conduct on-the-ground surveys and will only review and discuss the collected data—which has been criticised as ceding control to Beijing. 
• But other experts say this is a standard approach adopted by WHO—which relies on host countries to do most of the legwork. 
• As one American researcher points out: “I don’t imagine that the U.S. would invite Chinese scientists in to collect and analyze samples."

The big questions

The missing link: This coronavirus’ closest relative is a virus found in horseshoe bats—found in caves in the Yunnan province. But it only shares 96% of its DNA with this ancestor. Most importantly, the bat virus doesn’t possess the infamous spike protein that allows the coronavirus to attach itself to human cells. 

So there must be an intermediary species that enabled this mutation. And there are several suspects. For example, pangolins—but they were not listed as one of the animals sold at the Wuhan market. As the WHO notes:

“So far, susceptibility studies conducted in several countries have shown that domestic cats, ferrets, hamsters and minks are particularly susceptible to infection.”

A study of domestic and feral cats conducted last spring in Wuhan found that 14% tested positive for Covid. And we’ve since witnessed mass cullings of domesticated minks in Europe after authorities detected a mutant strain. Point to note: minks are also cultivated in China.

The market: At the outset of the pandemic, scientists believed that the virus jumped from animals to humans via wildlife meat sold at the Wuhan market. Now, we are not so sure:

“Of a sample of 41 early confirmed cases, 70% were stall owners, employees or regular customers of the Huanan market, which sold seafood but also live animals, often illegally captured in the wild and slaughtered in front of the customer. But the first confirmed case had no apparent connection.”

Now, scientists acknowledge that the virus could just as well have spread through the market via human-to-human transmission. 

Adding to the mystery: Authorities shut down the market on January 1 and thoroughly cleaned and disinfected its premises—and got rid of the animals. As a result, there are no blood samples to test for the presence of the virus. The new consensus: scientists say they won’t be surprised if the virus was circulating in the province for months before the first outbreak was detected in Wuhan.

Patient zero: is unlikely to be ever found. One reason is that the hunt is beginning more than a year after the Wuhan outbreak—since all countries prioritised battling the pandemic over tracking down the virus. But the bigger reason: coronavirus does not behave like more lethal viruses such as, say, Ebola—which was traced to a two-year old who played near a tree that housed bats. But Covid, in comparison, is a stealthy disease:

“It's possible the first people infected with coronavirus showed no symptoms at all. That, says [virologist Martin] Beer, has made piecing together the coronavirus puzzle, ‘very, very difficult.’

 

‘With respiratory diseases it is nearly impossible—it could be influenza or any other cold. [Coronavirus] patient zero themself probably does not know that they were, in fact, infected.’”

Early timeline: As a result, the best the WHO team can hope for is to reconstruct an early timeline of the spread of the disease. They will test biological samples—such as blood—that are routinely collected and stored at hospitals. They will compare samples taken before and after the Wuhan outbreak—ideally across China and neighbouring countries. Using these earliest cases, scientists will try and build a profile. What behaviours and occupations did these people have? Were they more likely to interact with certain animals? Or did they travel to specific locations?

Also key to the timeline: testing animals:

“The surveys collect samples of blood, urine, and feces 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 deploy routine measures for detecting infections… Some specimens would also be taken back to the lab to see if viable virus can be grown, a sign of a contagious infection.”

The bottomline: The WHO mission is absolutely vital to preventing future pandemics. One can only hope that China—which has been more focused on ‘saving face’—will see it the same way.

Reading list

Both National Geographic and The Guardian have excellent deep dives into the search for the virus’ origins. BBC News offers a good overview of the mission—and the politics surrounding it. Deutsche Welle explains why this mission matters. New York Times offers an overview of the Chinese propaganda efforts to ‘blame’ every other country—including India—for being the source of the virus. This Associated Press investigation reveals how Beijing has clamped down on any research on the Wuhan outbreak.