(WASHINGTON) — On the heels of a federal agency’s new assessment that COVID-19 “mostly likely” emerged from a lab leak rather than natural human exposure, a special panel formed by House Republicans to investigate the origins of the virus held its first hearing on Wednesday.

The House Select Subcommittee on the Coronavirus Pandemic, chaired by Ohio Republican Brad Wenstrup, met to tackle a question that’s plagued intelligence and health officials for the past three years: Where did the virus that has killed more than one million Americans and nearly seven million people worldwide come from?

The two prevailing theories are a leak from a laboratory in China, which the Chinese government vehemently disputes, or humans being exposed to an infected animal.

All of the witnesses who appeared before the panel agreed: The origin of COVID-19 is important to protect the world from future pandemics.

They also agreed that it will be difficult to know the truth without greater cooperation from the Chinese government.

As Director of National Intelligence Avril Haines noted Wednesday morning at a separate Senate hearing on global threats, there is “broad consensus” that the virus did not emerge as a bioweapon — but there is no such agreement on whether it came from an accidental lab leak or natural spillover.

Dr. Robert Redfield, who served as director of the Centers for Disease Control and Prevention under former President Donald Trump, doubled down in his testimony in the House that the “more likely” origin of COVID-19 was from an “accidental lab leak” as opposed to jumping to humans from animals.

Still, he said, “From the earliest days of the pandemic, my view was both theories about the origin needed to be aggressively and thoroughly examined.”

Redfield also said he believes the answer to COVID-19’s origin likely lies with the intelligence community, not with scientists.

When asked about an upcoming House vote to require the Biden administration to declassify intelligence related to the origins of COVID-19 — especially if there is “reason to believe” the Wuhan Institute of Virology in China may have been involved — Redfield said he supported it, with the exception of protecting sources and methods.

Both retired Dr. Anthony Fauci, the top COVID-19 official under Trump and President Joe Biden, and former National Institutes of Health Director Francis Collins have said that they believe the virus most likely originated in nature. But they have directly called for more research and collaboration with China on lab leak theories as well.

As he and others have previously said, Redfield testified that he believes in the lab leak theory because COVID-19’s structure looks “engineered” and in line with controversial gain-of-function research on viral genes, in addition to the “unusual actions in and around Wuhan in the fall of 2019.”

Other scientists have refuted the idea that the virus was tweaked or altered in a laboratory setting, saying a genetic analysis suggests it evolved in nature.

Redfield suggested before the House subcommittee that he had been sidelined from early scientific discussions, including within the government, because he didn’t agree with the preliminary consensus on where COVID-19 came from.

“This was a narrative that was decided, that they were going to say this came from a wet market, and they were going to do everything they could to support it — to negate any discussion about the possibility that this came from a laboratory,” he asserted.

Fauci, who was not at the hearing, later dismissed Redfield’s accusation as “completely untrue.”

“No one excluded anyone,” he told Politico. (ABC News has reached out to him for comment.)

U.S. agencies have said they remain “divided” on the matter and with no “smoking gun” and limited access to raw data, including via cooperation from China, discussion of the science has played out in a haze of circumstantial evidence.

Witnesses at Wednesday’s hearing also included Dr. Paul Auwaerter, a professor of medicine at the Johns Hopkins University School of Medicine, and Jamie Metzl, a former adviser to the World Health Organization and former national security official in the Clinton administration.

Metzl, in his testimony, said that “understanding how this pandemic began is essential to prioritizing our response” going forward and will help gear future oversight and attention to new threats.

“If, for example, we knew for certain the pandemic stems from a lab incident in Wuhan [in China], I can assure you that efforts to regulate the rapid proliferation of high-containment, and all too often high-risk, virology labs across the globe would get a massive boost,” Metzl said. “Critically important biosafety efforts would finally get the high-level national and international attention they deserve.”

“Understanding how this crisis began and determining how we can do better is and must be the ultimate bipartisan and nonpartisan issue,” Metzl said, urging pressure on and “demanding accountability from” Beijing.

“Doing so is not a hostile act, but the opposite,” Metzl said. “Supporting and joining a full and unfettered investigation has always been the best way for the Chinese government to demonstrate its commitment to understanding what went wrong.”

Metzl’s call for bipartisanship was echoed by lawmakers.

“I think you will see a strong bipartisan vote encouraging the intelligence community to declassify as much information as possible so the public can see the information that we have,” Rep. Ami Bera, D-Calif., said.

Republicans kept up a focus on Fauci, who has long been the target of conservative criticism and some right-wing conspiracies about how COVID-19 was created.

Rep. Mariannette Miller-Meeks of Iowa blamed “suppression and obfuscation” by Fauci and others, which “has led to the exact mistrust and distrust and conspiracy theories that they tried to avoid.”

Rep. James Comer of Kentucky, who is also the chair of the House Oversight Committee, more directly tried to link Fauci and Collins with allegedly being involved in the virus being developed in a lab — a claim without evidence.

China, for its part, has insisted it wants to find the truth even as it has been criticized for not complying with international investigations.

Chinese Foreign Ministry Spokesperson Zhao Lijian previously said in a statement, “Origins tracing is a matter of science. China always supports and will continue to participate in the science-based origins study.”

According to reporting in The Wall Street Journal last week, the U.S. Energy Department, which oversees a network of labs, said it now believes COVID-19 “most likely” was the result of a leak from a lab — an assessment in line with that of the FBI.

“The FBI has for quite some time now assessed that the origins of the pandemic are most likely a potential lab incident in Wuhan,” FBI Director Chris Wray said in response to the Energy Department’s evaluation, which the Journal wrote was made with “low confidence,” citing people who read the report.

Four other U.S. agencies, however, believe the virus was a result of natural transmission and that it jumped from animals to humans at a wet market. Two other agencies are undecided as to how it started.

“There’s just no consensus across the government. The work continues,” White House spokesperson John Kirby told reporters last week.

At Wednesday’s hearing, Redfield told the subcommittee members: “We need to get the intelligence community — and you will have the way to do that — I’d like to have you have each of them show what data they have, where they got it, who their informants were and what their conclusions were.”

“Because as you know, a number of them are on the fence. They don’t say yes or no,” Redfield said, referencing the FBI and Department of Energy’s belief that a lab leak is more likely, with varying degrees of low and moderate confidence.

Redfield said the two agencies have the “strongest scientific footprint of any of our intelligence agencies.”

Experts have said that, regardless of the number of hearings, successful investigation of COVID-19’s origins will almost certainly require fuller cooperation from the Chinese government. Looking into how outbreaks began takes extensive, on-the-ground scientific work.

Congressional Republicans have set their sights on investigating the origins of the virus, with House Republicans launching a probe not long after taking back majority control of the chamber.

A group of GOP senators are also now demanding to see the individual assessments on COVID-19 origins from each of the U.S. agencies.

“Congress should be able to review the independent evaluations without filters, ambiguity or interpretations of the intelligence,” a group of Republican senators, led by Kansas’ Roger Marshall, wrote in a letter sent Monday to Haines, who is set to separately appear this week before members of Congress’ intelligence committees.

“The ODNI has failed to be transparent with Congress and the American people by standardizing agency conclusions and thereby ignoring the breadth of scientific and other expertise in each agency,” the senators wrote.

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