Mysteries remain about the origin of Covid, says WHO report

In its first report, a team of international scientists brought together by the World Health Organization (WHO) to advise on the origins of the coronavirus said last Thursday that bats likely carried an ancestor of the coronavirus that would have spread to a mammal sold at a wildlife market. According to the team, however, there is a need for more data from China to study how the virus has spread to humans, including the possibility of a leak from a scientific laboratory.

The team, appointed by the WHO in October as the organization tried to redefine its approach to studying the origins of the pandemic, said Chinese scientists had shared information with them, including from unpublished studies, on two occasions. But gaps in Chinese data make it difficult to determine when and where the outbreak emerged, according to the report.

Independent experts said it was unclear how the team, made up of scientists from the United States, China and two dozen other countries, could help the WHO break through China’s political barriers, which have prevented the publication of most of the information that could set the record straight. the origin of the virus in the country.

“China’s lack of political cooperation continues to stifle any significant progress,” said Lawrence Gostin, director of the O’Neill Institute for National and Global Health Law at Georgetown University. He said the report offers a roadmap for investigating future pandemics in less sensitive countries.

The WHO asked the group for advice not only to study the origins of the coronavirus, but also to examine the emergence of future pathogens. The team, known as the Scientific Advisory Group on the Origins of New Pathogens, does not have the authority to carry out investigations in China or elsewhere.

Maria Van Kerkhove, the WHO’s Covid-19 technical lead, said the report was “just the beginning of her work”.

The group was expected to indicate greater openness to the thesis of a laboratory leak than the previous team sent by the WHO to China in early 2021. That team’s joint report with China said that a laboratory leak, while possible, was “extremely unlikely”. WHO Director-General Tedros Adhanom Ghebreyesus called this assessment premature.

According to the latest report, no new data indicates a lab leak. But the group’s leaders said they wanted to assess any evidence that might emerge in the future.

“We have not received any reports that actually indicate a laboratory leak that we feel is strong to follow up on,” said Marietjie Venter, team chair and professor of medical virology at the University of Pretoria in South Africa.

Efforts to study a laboratory leak met resistance from team members in China, Russia and Brazil, who saw no need for such investigations, the report said.

The document mentioned a number of studies on the potential role of animals in the emergence of the coronavirus that have been published since the previous work of the WHO team. For example, research at a live animal market in Wuhan, China, indicated that several species known to be susceptible to the coronavirus were present in the fall of 2019.

When people connected to this market started to get sick, the police closed and disinfected the place, making it more difficult for scientists to identify possible animal hosts that spread the virus.

The latest report said it focused on published, peer-reviewed studies, while acknowledging several unpublished studies posted online as “preprints”. Among them were two articles released this year in which a team of scientists argued that the pandemic arose when a bat infected a wild animal, a raccoon, for example, which was sold at the Huanan Seafood Wholesale Market in Wuhan.

Michael Worobey, an evolutionary biologist at the University of Arizona who helped carry out these studies, said it is unfortunate that the WHO team did not take a close look at the unpublished research.
“I think if you read our preprints and understand the evidence,” he said, “there’s actually very strong evidence that the pandemic came about through wild animals in the Huanan market.”

Worobey and other researchers said a vital opportunity had been missed in January 2020 to focus the search for the coronavirus on wildlife farms that supply markets like the one in Huanan. Instead, millions of animals were slaughtered.

Filippa Lentzos, a biosafety researcher at King’s College London, praised the latest report for commenting that the findings of Chinese studies on origin have not been published. But she said their proposals for future studies on the origin of the pandemic did not adequately take into account investigations into “accidental or deliberate events”, which she said would require experience outside of public health.

Jesse Bloom, a virus expert at the Fred Hutchinson Cancer Research Center in Seattle, said the report made it clear that mitigating future pandemic threats requires considering both animal and laboratory origins.

“Both are serious enough possibilities that need to be thought about together,” he said.
The report recommended studies of blood samples from workers at wild animal farms and live animal markets and of genomic data from early viral samples. But the previous WHO team had proposed similar studies, to no avail.

The latest report said Tedros twice wrote to Chinese officials in February, requesting information on the status of those studies, as well as a possible laboratory leak.

But there was no indication that the WHO would be able to convince China to share the results of such work.

Despite the difficulties, however, some information from China was leaked.

Last week, Chinese researchers published a small study on raccoons and bats collected in the Wuhan region in January 2020. In 15 raccoons the researchers found a new species of coronavirus related to another that infects dogs. In 334 bats, the researchers found coronaviruses that appear to be a mixture of viruses, some related to what caused Covid and others linked to what caused Sars in 2003.

“These sample sizes are not big enough,” said Maciej Boni, a virus expert at Penn State University. “We need sampling at the scale of tens of thousands of bats to get a complete picture.”

^{Translated by Luiz Roberto M. Gonçalves}