For those tracking the contentious debate over COVID-19’s origins, it’s been quite a few days.

On Tuesday, FBI director Christopher Wray publicly acknowledged that the Bureau considers an accidental biohazard leak from a laboratory in China to be the likeliest cause of the COVID-19 pandemic. The assessment had been made in August 2021, as part of an intelligence review ordered by President Biden. In an interview that aired on Fox News yesterday, Wray broke his silence on the matter, saying, “The FBI has for quite some time now assessed that the origins of the pandemic are most likely a potential lab incident in Wuhan.” He added, “Here you are talking about a potential leak from a Chinese government-controlled lab.”

Wray’s remarks came on the heels of a report in Sunday’s Wall Street Journal which revealed that the US Department of Energy had changed its position on the pandemic’s origins, based on new intelligence. The DoE now takes the view, albeit with “low confidence,” that COVID-19 “most likely arose” from a lab leak. The new assessment was noted in a classified intelligence report that was recently provided to the White House and certain members of Congress.  

This one-two punch of revelations immediately changed the optics, if not the ground-level reality, of the highly politicized and frequently toxic debate over COVID-19’s origins, which I first began reporting on in 2021. To be sure, there is still no clear proof that the virus escaped from a laboratory. But for the first time in at least two years, the possibility of a lab leak is being taken seriously even by many who previously considered it to be a baseless conspiracy theory.

For months, Democrats in Congress have declined to pursue a bipartisan inquiry into COVID-19’s origins, and the Biden administration did not press to include a plan for a bipartisan commission that would have examined the question in the last spending bill. Their hesitation was perhaps understandable, given the vehemence with which Republicans have pursued an openly partisan campaign to lay the blame for the pandemic at the feet of Dr. Anthony Fauci, the recently retired head of the National Institute of Allergy and Infectious Diseases.

There’s no guarantee that the events of the past few weeks will change Democrats’ calculus, but yesterday Senate majority leader Chuck Schumer appeared to acknowledge that the possibility of a so-called lab leak deserves to be taken seriously. “The bottom line is we’ve got to get to the bottom of this,” the Journal quoted Schumer as saying. “The Biden administration is committed to it. They have all kinds of people looking at it, and we’ll wait to see their results.” A Schumer spokesman would not say whether the senator now supports a bipartisan inquiry. 

For now, the outstanding questions far outnumber the answers. There is fragmentary and circumstantial evidence supporting two credible but dueling hypotheses: one, that SARS-CoV-2, the virus that causes COVID-19, spilled over to humans from an infected animal at the wet market in Wuhan where the disease first exploded into view; or two, that the virus originated in a nearby laboratory in Wuhan. The Wuhan Institute of Virology, which was known to pursue risky coronavirus research, is roughly eight miles from the market. Even closer sits the Wuhan Center for Disease Control and Prevention, which also operates laboratories.

The World Health Organization, which has been largely stonewalled by China in its efforts to probe the pandemic’s origin, contends that both hypotheses remain on the table.

China has long denied that COVID-19 originated from a Wuhan laboratory, or even within its borders. On Monday, a Chinese foreign ministry spokesperson said at a press briefing, “The origin of the novel coronavirus is a scientific issue and should not be politicized.” 

As of last night, it was not clear what new intelligence led the Department of Energy to change its assessment. That information, which remains classified, was reportedly shared with other intelligence agencies, which did not alter their assessments.

But the shift by the Department of Energy is notable, as it funds and oversees a network of 17 national laboratories, including the Lawrence Livermore National Laboratory in California, which possesses advanced national security capabilities.  Dr. Robert Redfield, the former director of the Centers for Disease Control and Prevention under President Trump, says that both the Energy Department and the FBI have a “huge scientific workforce,” making their assessments of a lab origin significant.

Others are reserving judgment until more details emerge. “It’s very difficult to say anything until we see what information drove this updated analysis,” says Stephen Goldstein, a post-doctoral research associate in evolutionary virology at the University of Utah who coauthored an influential research paper linking COVID-19’s origin to the wet market. The Energy Department “showed it to other agencies and they did not change their assessments, and it’s low confidence,” Goldstein adds. “If the data exists and is declassified and I can update my own analysis, wonderful.”

In May 2021, President Biden ordered the US intelligence community, including the FBI, CIA, and offices at the Departments of State and Energy, to conduct a 90-day review of the origins question. A declassified account of their findings reflected broad consensus on several key points: that SARS-CoV-2 likely first appeared in Wuhan no later than November 2019, that it emerged without the foreknowledge of China’s government, and that it was not developed as a bioweapon. Most agencies also agreed that the virus “probably was not genetically engineered,” though two agencies believed they did not have enough evidence to make a determination. 

The agencies split, however, over the question of how the virus made the leap to humans. The National Intelligence Council and four other agencies favored a natural origin, albeit with “low confidence,” and three others remained undecided. One unnamed agency—which turned out to be the FBI—assessed with “moderate confidence” that the first human infection with SARS-CoV-2 most likely resulted from a laboratory-associated incident, probably involving experimentation, animal handling, or sampling by the Wuhan Institute of Virology, the summary stated.

This sober-minded inquiry by intelligence professionals unfolded in stark contrast to the often bitter debate raging in the press and on social media. In the early days of the pandemic, the claim that COVID-19 leaked from a laboratory was part of a broader conspiratorial narrative pushed by fringe figures. Steve Bannon, a far-right adviser to President Trump, linked arms with a Hong Kong billionaire to elevate wild and unsupported claims, such as the notion that the Chinese Communist Party had developed COVID-19 as a bioweapon.

In April 2020, after President Trump asserted, without offering evidence, from the White House podium that the virus had come from a Wuhan laboratory, the political battle lines hardened. The mere suggestion that a laboratory leak might have occurred became associated with xenophobic, anti-scientific, and often flatly untrue claims being driven from the right.

Even as more legitimate questions surfaced around the lab-leak hypothesis, most mainstream media continued to present the market origin as settled science, and one that enjoyed a consensus among scientists.  

One set of studies, in particular, led scientists and journalists to continue asserting  that the spillover theory was far likelier than the lab alternative. In July, a group of leading virologists published two peer-reviewed papers that analyzed early cases of infected patients in Wuhan, using geospatial mapping. They concluded that SARS-CoV-2 “occurred through the live wildlife trade in China” and that the Wuhan market was the “epicenter of the COVID-19 pandemic.”  

On Monday, Fauci told The Boston Globe at a health and biotech conference that he believes that the mapping analysis “rather strongly suggests” that the virus emerged as a “natural occurrence.” Stephen Goldstein, one of the paper’s coauthors, says that although he believes the evidence points strongly to the market in Wuhan, “We acknowledge in the paper, there are still elements of this that are unknown.”

Over the last two years, however, a more complex picture has emerged, bit by bit, due to the work of Freedom of Information research groups, a small number of scientists and journalists, and a group of online sleuths calling themselves DRASTIC. 

It turned out that the National Institutes of Health (NIH) had allowed a US scientific research nonprofit called EcoHealth Alliance to provide subgrants of federal funding to the Wuhan Institute of Virology (WIV), which were used to support risky coronavirus research. (The Department of Health and Human Services’ inspector general recently determined that the NIH had failed to appropriately oversee the central grant in question.) 

It also turned out that some of the earliest and most persuasive arguments against a possible laboratory origin came from scientists who initially suspected a lab origin was likely, as revealed in emails obtained through Freedom of Information requests.

And it emerged that EcoHealth Alliance, in partnership with a University of North Carolina virologist and the WIV’s top coronavirus researcher, had in March 2018 sought a grant from the Defense Advanced Research Projects Agency (DARPA). As part of their grant application, they proposed to insert a feature known as a furin cleavage site into unidentified SARS-like bat coronaviruses to assess their ability to infect cells. This raised eyebrows given that one of the most notable features of SARS-CoV-2 is its unique furin cleavage site, not found in any other known SARS-like virus. 

DARPA declined to fund the grant, determining that the proposal had failed to adequately assess the risks of the research. The president of EcoHealth Alliance, Peter Daszak, has said that to his knowledge none of the collaborating partners on the grant continued the research, but it’s unclear whether it nevertheless went forward in some way. 

Lawrence Tabak, acting director of the NIH, recently testified at a hearing held by the House Energy and Commerce Committee that the viruses the WIV studied using his agency’s funding could not have sparked the pandemic as they “bear no relationship to SARS-CoV-2; they are genetically distinct.” But the full picture of the work that was done at the Wuhan Institute of Virology remains shielded from public view. The WIV first took down its extensive database of virus sequences in September 2019, and it remains offline today.

With critical information still out of reach, scientists and sleuths have battled continually over the few available clues. The rancor, meanwhile, has ratcheted up to a point that scientists on both sides of the debate have received death threats. Virologists who early in the pandemic advised the government, particularly the NIH, find themselves facing hostile GOP congressional committees and the prospect of subpoenas.

Probing the virus’s origin is important, says Goldstein. But “some of the rhetoric of those [congressional] letters is so hostile from the jump that it alienates people from wanting to participate in those investigations.” He has not been personally targeted, but some of his coauthors have.

For those who have seriously studied the question of whether COVID-19 could have originated from a laboratory, it has been a difficult and lonely road. Alina Chan, a molecular biologist at the Broad Institute in Boston, was one of the first scientists to argue that COVID-19 may have originated in a lab. She has argued her case on Twitter, and copublished a book, Viral, exploring the question with a British science writer, Matt Ridley. Throughout, she has been relentlessly assailed online by critics, including establishment scientists, who denounce her as a conspiracy theorist and grifter.

“Some powerful proponents of the natural spillover hypothesis have gone out of their way to degrade and intimidate those asking for a fair investigation of the lab-leak theory,” Chan told Vanity Fair. “No matter how much abuse they heap on us, the lab leak has always been a plausible origin of the pandemic.”  

Amid the overheated debate, journalists investigating the possibility have also been targeted. In October, critics demanded that ProPublica and Vanity Fair retract an investigative report on the Wuhan Institute of Virology, arguing that it relied in part on faulty translations of Chinese-language documents. An extensive review by both publications affirmed that the reporting was “sound” and that the lab-leak hypothesis is an “essential avenue for exploration.”

Since the Wall Street Journal’s story on Sunday, even the comedian Jon Stewart has expressed bewilderment at the attacks he faced after he joked to Stephen Colbert in June 2021 that it was obvious COVID-19 came from a Wuhan laboratory. As he noted on his Apple TV+ podcast Monday, “The larger problem with all of this is the inability to discuss things that are within the realm of possibility without falling into absolutes and litmus-testing each other for our political allegiances.”     

Without cooperation from China’s government, which virtually no one believes is forthcoming, it will be difficult if not impossible to say for sure how the pandemic began. But US efforts to shed light on the question—and prevent future pandemics—continue all the same. As the intelligence agencies weigh declassifying crucial information and GOP-led congressional committees continue to pursue hearings, the Biden administration appears poised to move forward with more stringent regulations of risky pathogen research, despite the opposition of many virologists. 

“The fact that it’s plausible that a lab accident could have caused a global pandemic is a wake-up call for all of us,” says Jaime Yassif, vice president of global biological policy and programs for the Nuclear Threat Initiative. “If we don’t take bold action now to guard against accidental or deliberate misuse of bioscience and biotechnology, we could face catastrophic consequences in the future, which could be as bad as COVID or worse.”