WHO ‘Compromise’ report hardly resolves origins of pandemic, but details next steps in investigation | Science

By Kai KupferschmidtApple. 30, 2021 at 10:00 a.m.

ScienceCOVID-19 reports are supported by the Heising-Simons Foundation.

Where SARS-CoV-2 came from before it began its 15-month rampage around the world is the biggest pandemic puzzle. But a long-awaited report on the matter released today may satisfy few readers, especially given unrealistic expectations about how quickly the source of the coronavirus could be identified. Produced by an international team of scientists after a carefully negotiated visit to China, where COVID-19 was first recognized, the report concludes that the most likely start of the pandemic was a bat coronavirus that infected another unidentified animal, then passed on to humans.

This has long been the favored hypothesis of many virologists, but the team convened by the World Health Organization (WHO) reports little new evidence to support it, and members acknowledge that several other scenarios, including a accidental release from a laboratory, remain possible. However, the report sets out many steps ahead. “We still don’t know where the virus came from, but there is a clear plan to continue investigating,” says virologist Angela Rasmussen of Georgetown University, who was part of the WHO team.

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The report was co-authored by 17 international experts, selected by WHO and approved by China, and an equal number of Chinese scientists. The group had been working together for months before the WHO expert visit in January, when they reviewed data compiled by Chinese colleagues, visited sites potentially linked to the origin of the pandemic, and debated the probability of different scenarios.

The report’s most definitive conclusion is also the most controversial: It is “extremely unlikely” that SARS-CoV-2 leaked from a Chinese laboratory that was already studying coronaviruses, the Wuhan Institute of Virology (WIV). There is little evidence to support the laboratory escape hypothesis, but some researchers have criticized WHO team members for everything, but have ruled out the possibility when they weren’t allowed to. investigate independently. WHO experts have only spent a few hours at WIV and discussion of the lab leak scenario report is sparse.

It’s understandable, some researchers say. “Given all the constraints and complexities here, they probably did what they could,” says Yanzhong Huang, global health specialist at the Council on Foreign Relations in New York.

Rasmussen agrees. “A team of scientists is not qualified to perform a detailed audit of WIV records, or to access institutional files, lab notebooks, databases or freezer inventories,” she says. “WHO also does not have the power to walk around China and ask them to give them unhindered access to WIV, China CDC [Center for Disease Control and Prevention], or any other institution. “

In a briefing today on the report, WHO Director-General Tedros Adhanom Ghebreyesus stressed that more studies were needed to understand the origins of the SARS-CoV-2 virus, and criticized the access given to its international team during its fact-finding mission to China. . Tedros said he expected “future collaborative studies will include more timely and comprehensive data sharing. … Although the team concluded that a lab leak is the least likely hypothesis, it requires further investigation, possibly with additional missions involving specialist experts, which I am prepared to deploy.

Also today, the US government and 13 other countries released a statement that echoed Tedros’ criticism and called for further research into the start of the pandemic. “Together, we support a transparent and independent analysis, without interference or undue influence, of the origins of the COVID-19 pandemic,” the statement said. It was jointly published by Australia, Canada, Czech Republic, Denmark, Estonia, Israel, Japan, Latvia, Lithuania, Norway, South Korea, Slovenia, United States and the United Kingdom.

“The study by international experts into the source of the SARS-CoV-2 virus has been significantly delayed and has not had access to original and complete data and samples,” the statement said. He called for a “renewed commitment by WHO and all Member States to access, transparency and speed.”

Most of the report’s findings were presented at a press conference last month and in numerous media interviews by members of the WHO team. Yet, at more than 300 pages, it presents the data that the joint team of international and Chinese experts reviewed, including studies on the Huanan market in Wuhan with which some of the first cases of COVID-19 have been in. contact.

The report describes four scenarios of how the pandemic could have started and assesses their likelihood:

1. Transmission of SARS-CoV-2 from an animal reservoir such as bats to another host in which the virus has spread before infecting humans. The team describes this scenario as “likely to very likely”.
2. Direct spill onto people from an animal reservoir such as bats – considered “possible to probable” by the team.
3. Spillover via frozen meat from an infected animal, a route the team called “possible.”
4. A laboratory incident leading to the first infection – the only scenario deemed “extremely unlikely”.

China has strongly refuted the laboratory hypothesis while pushing the possibility that the infection could have arrived from outside China on frozen foods, and some members of the WHO international team point out that the The report’s conclusions reflect what the international team and its Chinese counterparts might agree on. . “This whole report is a compromise,” says Fabian Leendertz, animal veterinarian at the Robert Koch Institute in Germany and member of the international team. “And in a compromise, you have to respect the other’s point of view.”

The report recommends a series of further studies, in particular sampling of the virus in wild and farm animals to find a possible intermediate host. But the search for the original animal reservoir of SARS-CoV-2 may be very promising, says Leendertz. “At this point, it is possible that it has disappeared from any intermediate host, so sampling bats, in particular, is probably the most likely to yield results.”

Further investigations into the early days of the pandemic are also needed, says Thea Kølsen Fischer, a virologist at the University of Copenhagen and a member of the international team. We still don’t know when people started to get sick. In published research, scientists described three cases of respiratory illness in China in early December 2019, believed to be COVID-19.

But the Chinese contingent of the WHO investigation told members of the international team that they no longer believed those patients had SARS-CoV-2. The first case was a 62-year-old man who developed symptoms on December 1, 2019. He appeared to respond to antibiotics but became sicker later in the month and Chinese scientists reported in a journal article in 2020 that he had “laboratory confirmed” COVID -19. Although he had no contact with the Huanan market, his wife, who was hospitalized on December 26 and tested positive for COVID-19, told investigators she did. This case and the other two have been discussed at length, says Fischer, and require further study. “We did not come to a 100% agreement to dismiss these cases.”

The Chinese team also looked at more than 76,000 other potential early cases of COVID-19 – people with fever and other symptoms of the disease – and found no clear SARS-CoV-2 infections. A study of blood samples from the Wuhan blood bank to look for the first cases of COVID-19 is another recommended step – although some foreigners have expressed bemusement, it has yet to be done more than 15 months afterwards. the start of the pandemic.

From the start, scientists on the WHO team and outside have pushed back against the idea that a short mission would quickly pinpoint the origins of the pandemic. The politically charged environment surrounding the WHO investigation did not help matters, Rasmussen notes.

The report is just a first step, adds Fischer. “I feel like I’m standing in front of this wall and now holding this piece of string in my hands, but I don’t know how long that string is on the other side of the wall. Maybe it’s short, and it will be months away, or maybe it’s long and it will take years.

* Update, March 30, 3:30 p.m .: Comments from the WHO Director General and an international statement were added.