Did COVID Originally Leak From a Chinese Lab? Politics May Prevent Us Ever Knowing for Sure

China has been quick to try to dispel reemergent COVID-19 “lab leak” theories following a Wall Street Journal report this past weekend that the U.S. Department of Energy has concluded—albeit with “low confidence”—that the virus behind the pandemic most likely originated in a Chinese laboratory. The FBI has also determined that a lab is the most likely source of the virus.

Mao Ning, spokesperson for China’s foreign affairs ministry, told reporters Monday that “certain parties” should “stop smearing China” and that the “lab leak” theory has already been authoritatively deemed “extremely unlikely.” Mao emphasized: “The origins-tracing of SARS-CoV-2 is about science and should not be politicized.” But the science isn’t settled yet.

Researchers around the world have been endeavoring since the outbreak began in 2020 to determine the provenance of the virus. Knowing how the pandemic started, experts believe, can significantly aid the efforts to bring it to an end—and prevent future pandemics. But three years and nearly seven million lives lost later, there’s still little certainty over whether the virus first naturally infected humans at a seafood market in Wuhan, as many scientists originally believed, or escaped a laboratory, as the Energy Department now reportedly believes based on undisclosed new intelligence. And at this point, experts worry that due to the charged atmosphere surrounding such investigations, we may never be sure.

“The origin probe is so politicized,” says Yanzhong Huang, a global health expert at the Council on Foreign Relations, who notes that the revelation of the U.S. Energy Department report comes as U.S.-China tensions have risen in recent months. “It is just becoming increasingly difficult to find out what exactly caused the outbreak. I would say it’s almost impossible now, with all this delay, with the politicization of the issue.”

At the beginning of the pandemic, Republicans in the U.S., most prominently former President Donald Trump, were quick to promote the lab leak theory, asserting that China was to blame for the outbreak. But while that suggestion initially seemed ideologically motivated to some—and aligned with a rise in anti-China rhetoric—there’s since been an increasing acknowledgement that the theory can’t be ruled out.

“There is not a consensus right now in the U.S. government about exactly how COVID started,” National Security Council spokesman John Kirby said during a White House press briefing Monday. “The work is still ongoing. There hasn’t been a final conclusion arrived at here. And not everyone in the intelligence community or across the government necessarily has come to a consensus view here on how it started.”

Read More: What We Know About the U.S. Intelligence Community’s Split on COVID-19 Origins

Either way, there likely won’t ever be “smoking gun evidence,” says Huang. And that’s because China has also politicized its response.

When the Australian government called for an independent probe into the virus’ origins in Wuhan in 2020, China retaliated by imposing trade sanctions on Australia’s exports. China claims its joint investigation with the World Health Organization in 2021 came to an “authoritative conclusion” against the lab leak theory, but the WHO itself says all hypotheses on COVID-19’s origin remain open. And when the WHO sought to further investigate, China refused to cooperate. The former head of MI6, the U.K.’s foreign intelligence service, has speculated that any direct evidence that could point to a possible lab leak would have been destroyed by now by Chinese officials.

The problem, says Ayelet Berman, who leads the Global Health Law and Governance Program at National University of Singapore’s Center for International Law, is that in the existing political climate, China has nothing to gain from being more transparent. And that sets a dangerous precedent. Berman says that inquiries and research on future outbreaks may be similarly hampered by origin countries’ fears of facing economic and social backlash.

“All of the other outbreaks over the years—if you think about Zika, MERS-CoV, SARS-CoV-1, Ebola—there wasn’t really any problem to investigate the origin because the countries collaborated,” Berman said. That isn’t the case anymore. “It’s a big problem that needs to be addressed.”