The Washington PostDemocracy Dies in Darkness

The Wuhan lab-leak theory is getting more attention. That’s because key evidence is still missing.

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A new surge of interest has revived the lab-leak theory. Well over a year since a novel coronavirus began to spread in Wuhan, the idea that the deadly outbreak could be linked to a virus research center in the Chinese city has lingered, unproven but not eliminated.

Although the resurgent chatter may suggest new clues or proof, the inverse is in fact true. It is the persistent absence of any convincing evidence either for or against the theory that has prompted calls for more investigation.

President Biden said Wednesday that the U.S. intelligence community does “not believe there is sufficient information” to fully understand the likelihood of different scenarios for explaining the origin of the virus that causes covid-19.

At least publicly, the evidence in favor of a link between the outbreak and the Wuhan Institute of Virology (WIV) has not changed significantly in months, and many virologists still have persistent doubts that such a link exists.

What has clearly changed, however, is the political debate. Most obviously, a new U.S. administration that is not so openly anti-China has led some former skeptics to reconsider the existing evidence. And public health experts — most of whom never ruled out the lab theory outright — have expressed disappointment with a World Health Organization-backed investigation that dismissed a link between WIV and the outbreak.

In the absence of crucial evidence of how the new coronavirus began comes many theories — one is that the virus accidentally escaped from a lab in Wuhan, China. (Video: Sarah Cahlan, Meg Kelly/The Washington Post)

The annual World Health Assembly this week brought new calls to significantly expand upon the WHO-backed investigation, which concluded in March. Biden on Wednesday announced that he was asking the U.S. intelligence community to “redouble its efforts” to collect information about the coronavirus’s origin.

The United States would continue to partner with “like-minded partners around the world to press China to participate in a full, transparent, evidence-based international investigation,” Biden said.

So far, though, there is certainly no smoking gun. Here’s where things stand:

The public evidence for or against the lab leak is nowhere near decisive.

The lab-leak theory emerged in January 2020, when the virus was still mostly confined to China and had killed hundreds, rather than millions.

Links between WIV and the virus were floated in right-wing news organizations like the Washington Times, while former White House strategist Stephen K. Bannon questioned whether there was a link between the virus and “bioweapons research” in China.

Experts quickly dismissed the idea that the coronavirus was intentionally developed as a bioweapon, but vaguer questions about the link between WIV and the virus, including those asked by Sen. Tom Cotton (R-Ark.) in February 2020, were harder to answer.

In April 2020, journalists including The Washington Post’s David Ignatius and Josh Rogin suggested that a bat virus being studied in potentially risky experiments could have escaped the lab.

For example, “gain-of-function” experiments examining how viruses found in animals can infect humans are noble in aim and designed to prevent future pandemics. But Rogin reported that U.S. officials had raised concerns about safety at WIV in 2018. “Whether the staff are interacting with bats in the wild or in the lab, they are routinely putting themselves at risk of infection,” one unnamed U.S. scientist told a team of Post reporters for an April 30 report.

Most pandemics, however, have emerged via a simpler route: passing from an animal to a human through “zoonotic” infection. Plenty of virologists still argue that this was the most likely path of the novel coronavirus.

But there is still a dearth of evidence about this coronavirus’s origins. Without full cooperation from Chinese authorities, clues have primarily come out in dribs and drabs from intelligence leaks or complicated analyses of genetic code.

Some analysts have complained about the unproved provenance of leaked intelligence, including the detail in a recent Wall Street Journal report that WIV staff may have fallen ill in 2019 with covid-like symptoms.

The WHO-led investigation into the virus’s origins only spurred interest in the lab-leak theory.

Prominent virologists, many of whom had been hesitant to speak out publicly before, are now openly calling for a broader investigation.

Eighteen prominent scientists on May 14 published a letter in the journal Science arguing that “theories of accidental release” remained “viable.” Among them was Ralph Baric, a virologist who worked with Shi Zhengli, a renowned expert on bat coronaviruses based in Wuhan, who is central to many lab-leak hypotheses.

Their timing was motivated by this week’s World Health Assembly and a desire to point out the perceived weaknesses of the WHO-backed investigation.

That probe saw a team of 17 international experts fly to Wuhan to visit WIV themselves. It found that a “very likely” scenario involved an unknown animal passing the virus to humans.

The WHO team dismissed the lab-leak idea as “extremely unlikely.” Indeed, its report spends considerably more time discussing a theory that the virus was imported on frozen food, an idea pushed by Beijing that has little international support.

Even to the leak theory’s skeptics, that was a stretch.

The dismissive attitude to the lab-leak theory furthered criticisms that the WHO team was too close to Chinese experts: Peter Daszak, head of the nonprofit EcoHealth Alliance, had been a colleague of Shi, the Wuhan coronavirus expert, for 15 years. The team only got three hours to visit the lab.

“At the end of the day, they show us what they show,” Hung Nguyen-Viet, a Vietnamese expert on livestock and human health who joined the trip, told The Post.

Speaking at a news conference in March, WHO Director General Tedros Adhanom Ghebreyesus said that the lab-leak theory “requires further investigation” and that he was ready to deploy specialists on additional missions.

It is still not clear what the endgame is.

Biden’s announcement on Wednesday lent credence to the lab-leak theory: Some Democrats are now backing calls for a congressional inquiry. The president set a 90-day deadline for the intelligence community to come “closer to a definitive conclusion” and pushed for more international pressure on China.

Yet Biden also admitted that the intelligence community so far only had “low or moderate confidence” in its assessments. Without Chinese cooperation, it is unclear how these bodies would be able to reach new conclusions within a three-month period.

Broader international pressure could well stumble against China, which wields veto power not only at the World Health Assembly, but also at the U.N. Security Council. Plus, it isn’t clear what standard of evidence would satisfy partisans on either side of the divide on the lab-leak theory, if any.

We may never know exactly how the coronavirus that causes covid-19 spread to humans. Scientists still haven’t pinpointed the origin of the influenza strain that killed millions in 1918. Although civet cats were speculated within months to be the intermediate host in a 2003 SARS outbreak, it took years to confirm it.

It wasn’t until 2017 that that virus was finally traced back to bats. The lab that solved the mystery? The Wuhan Institute of Virology.

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