President Joe Biden has ordered U.S. intelligence agencies to determine whether the Covid virus, or a near ancestor, emerged from a cave, a live-animal market, a farm — or a secretive Chinese laboratory.

But it's doubtful this probe will yield definitive insights, and it could even backfire.

Some experts hypothesize that global pressure could prompt a Chinese scientific whistleblower to come forward with evidence of a lab leak. After all, it is unlikely such an accident could have occurred without dozens of people finding out about the leak, or an ensuing cover-up.

But the growing political pressure to discover Chinese malfeasance or a lab accident at the root of the pandemic could make a definitive answer less, rather than more, likely, according to virologists and experts on U.S.-China scientific exchanges.

"We have to reduce the political tension and let the scientists do the work, not the politicians," said Dr. Jennifer Huang Bouey, a Chinese-born Rand Corp. researcher.

Yet that seems like a pipe dream. In the United States, the lab leak theory is part of the conservative arsenal of attacks on those in science and the media who criticized President Donald Trump's handling of the pandemic. For the ruling Chinese Communist Party, the political implications of acknowledging a lab leak and subsequent cover-up are a non-starter. It would leave China essentially responsible for starting a global pandemic that has killed 6 million and ground economies to a halt.

As Biden last week announced a 90-day review of evidence on the virus's origin — which could involve a review of documents from U.S. agencies that helped fund Chinese viral research— Chinese officials at a World Health Organization meeting dismissed the review and withdrew a promise to cooperate with scientists examining the full slate of origin possibilities.

During its visit to China in February, a WHO investigative team received agreement from Chinese blood banks to preserve samples of donations that could indicate when and where the virus might have been circulating before it swept over the city of Wuhan in December 2019.

The team wants to go back to China, extending its investigation to markets and farms where animals like civet cats, raccoon dogs and bamboo rats — potential carriers of the virus as it leaped from bats to humans — were raised as part of a $70 billion "wildlife farming" industry. In 2003, China banned the sale of such exotic wildlife at "wet markets" — which mainly sell fish and game like live chickens — after they were implicated as the origin of the SARS epidemic, though such animals have returned to markets over the years.

Further study is impossible without Chinese cooperation, which is mired in politics, the WHO investigators say.

"We're not following all these obvious leads now," Dr. Marion Koopmans, a leading Dutch virologist who was part of the WHO team, said last week. "Everything is stalled."

Her team has been criticized for caving to Chinese pressure by failing to seek a strict audit of the Wuhan Institute of Virology, the center of allegations about a lab leak. But to forcefully demand such an audit would require evidence of a leak, rather than speculation based on classified intelligence reports and theoretical gaps in data, Koopmans said. Besides, the Chinese government won't open its books. It has closed access to the data, claiming there had been thousands of hacking attempts against the Wuhan Institute.

That awkward standoff could harm U.S.-Chinese scientific cooperation, which has gradually expanded over the past 40 years and remained strong despite Trump administration attacks. Whether a lab leak happened or not, it's hard to see how a weakening of scientific exchanges would be a good thing for either country.

Full-tuition-paying Chinese students made up the majority of the international enrollees at U.S. colleges and universities in 2019, though Chinese interest in U.S. schools seems to be ebbing. U.S. laboratories depend on Chinese scholars, many of whom end up remaining in the United States. Scholars from the two countries co-publish scientific papers more often than any other national "dyad," according to research by Caroline Wagner of the Ohio State University.

But those partnerships have had their hiccups, sometimes for political reasons. With AIDS and SARS, the Chinese were either reluctant to allow their scientists to release data or released counts that many Western experts doubted were accurate.

Trump curtailed scientific exchanges as early as 2017, issuing fewer visas and raising FBI vigilance of academics with ties to China. Some interagency agreements were allowed to lapse and, in 2018, a 45-member Centers for Disease Control and Prevention contingent in China was cut to 10. Trump saw this as a punishment of the Chinese, but it effectively blinded the U.S. to the goings-on in Chinese epidemiology.

Otherwise, "maybe we'd have had a quicker leg up on the outbreak," said Ben Corb, spokesperson for the American Society for Biochemistry and Molecular Biology.

Despite his anti-China stance, Trump in 2018 renewed a landmark 1979 agreement authorizing scientific and technological cooperation among the Chinese and U.S. governments. However, that renewal document is secret — presumably, Trump was not happy to have to take the advice of his scientific advisers — and it's impossible to come by a copy, according to Duke University business professor Denis Simon, an expert on the US-China scientific relationship.

The Biden administration is said to favor improving scientific cooperation — for example, by easing limits on visas for Chinese scholars. And while Trump clearly viewed the lab leak hypothesis as an opportunity to blame China for the administration's misfortunate Covid response — an association that tarnished the theory's plausibility during the Trump years — Biden seems to want an answer to the question, at least in part to prevent future pandemics.

Since the turn of the century and especially since SARS, China has sent many biologists to train in the United States, and they are now leery of being seen as unreliable partners in disease investigations. The Chinese government has copied many aspects of the U.S. scientific and public health system, Bouey noted. Close collaborations and friendships have resulted. Toward the beginning of the pandemic, Dr. Anthony Fauci, the National Institutes of Health's top infectious disease specialist, was in regular contact by email with George Gao, the Oxford- and Harvard-trained scientist who runs China's equivalent of the CDC.

Even with Chinese government cooperation, we might never know how Covid began. But if the intelligence review suggests or manages to determine that a lab leak did cause the pandemic, and China continues to stonewall, it's hard to predict what might happen.

"I think there will be hell to pay," said Simon. "We haven't figured out the consequences to the answer. I'm very concerned about our ability to manage the emotions loosed if that hypothesis were to be accepted."

This story was produced by KHN, which publishes California Healthline, an editorially independent service of the California Health Care Foundation.

This article was reprinted from khn.org with permission from the Henry J. Kaiser Family Foundation. Kaiser Health News, an editorially independent news service, is a program of the Kaiser Family Foundation, a nonpartisan health care policy research organization unaffiliated with Kaiser Permanente.