Updated July 29, 2026 at 3:08 PM EDT
Anthony Fauci declined to answer any questions before a Senate committee focused on the coronavirus pandemic Wednesday morning.
"Although it pains me to do so, because of the respect I have for the legislative branch of government, and my decades-long record of cooperating with Congress, under the advice of my attorneys, I will invoke my right under the Fifth Amendment of the Constitution to refrain from answering your questions," Fauci said in front of the Homeland Security and Governmental Affairs Committee.
Fauci, the country's leading infectious disease specialist during the COVID-19 pandemic, was subpoenaed to appear by Kentucky senator and committee chair Rand Paul. He has long sparred with the senator over the origins of the coronavirus that caused the pandemic.
Days before Wednesday's hearing, Paul released over 1,000 pages of Fauci's private diary entries about his daily life between December 2019 and 2022, accusing him of covering up the origins of COVID-19. The entries span the final years of his tenure as director of the National Institute of Allergy and Infectious Diseases (NIAID). He retired in December 2022.
At the hearing, Fauci pointed out that he has responded to similar questions in previous testimony. And Fauci accused the senator of being obsessed with trying to get him behind bars.
Paul posted the documents over the weekend, took them down on Monday evening and reposted them by Tuesday morning with redactions. Paul also released a 465-page "prequel," a collection of Fauci documents including records and email exchanges from 2001 to 2015.
On his website, Paul pointed to Fauci's entry from Feb. 1, 2020, detailing a conference call between Fauci and prominent scientists.
In his notes, Fauci writes "there was not total agreement" about the virus' origins during the call.
Later in his entries, however, Fauci writes he "is almost certain that the virus evolved naturally from a species jump, even though … I keep an open mind about the possibility of a lab leak," and "that just because two alternatives are possible that does not mean that they are equally probable."
Many scientists say this thought process reflects how their consensus changed as the understanding of COVID-19 evolved.
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Debate that won't abate
The hearing follows years of debate about the pandemic's origins, and whether the virus that causes COVID-19 emerged accidentally or intentionally from the Wuhan Institute of Virology, a Chinese laboratory which has studied bat coronaviruses.
The lab is located in the city where the first cases of COVID were recorded.
Paul alleges Fauci's notes show he covered up evidence supporting this "lab leak" theory.
In a thread on X over the weekend, Paul wrote that the diary entries show what Fauci "wrote privately and what he told the country are two different stories."
A spokesperson for Fauci sent a document fact-checking Paul's claims and a letter written by Fauci's legal team to Paul last month. In that letter, Fauci's lawyers wrote Paul was waging a "years-long public crusade" against Fauci.
"You are single-mindedly fixating on seeing Dr. Fauci prosecuted for imaginary crimes, and you are so invested in that outcome that you have created a personal brand around it," says the letter, which NPR reviewed.
Paul did not respond to NPR's requests for comment in time for publication. It is also unclear how Paul obtained the Fauci diary documents, though a video posted Tuesday on X by Health Secretary Robert F. Kennedy Jr. mentions digging them "out of 11 separate servers."
Consensus for natural origin
The current scientific consensus is that SARS-CoV-2, the virus that causes COVID-19, is likely natural in origin. In a report issued in June 2025, the World Health Organization stated: "the weight of available evidence … suggests zoonotic spillover … either directly from bats or through an intermediate host."
That conclusion was based on three years of research by the 27 members of The WHO Scientific Advisory Group for the Origins of Novel Pathogens.
NPR's reporting has supported that theory. In 2024, we covered an analysis by a team of scientists that included prominent names such as Michael Worobey and Angela Rasmussen. NPR noted that their research, published in the peer-reviewed journal Cell, "shows with unprecedented granularity — down to the individual market stall — that coronavirus-susceptible wildlife and the SARS CoV-2 virus were mingling, along with human beings, in a very specific part of the Wuhan market."
The Trump administration has in the past advanced the theory that the pandemic was caused by the virus escaping the Wuhan Institute of Virology. Leaked cables from the State Department raised concerns about safety protocols at the Wuhan lab.
Supporters of the lab leak theory note scientists' analyses relied on incomplete data provided by the Chinese government.
Among U.S. government agencies, some lean toward supporting a natural origin for the virus, while others — including the Department of Energy and the Federal Bureau of Investigation — support a lab origin, although the former has "low confidence" about its conclusion.
NPR reported at the time that "low confidence" meant "the information used in the analysis is scant, questionable, fragmented, or that solid analytical conclusions cannot be inferred from the information," according to the federal government.
One thing is certain: Six years after the start of the pandemic, there is still debate.
The director-general of the World Health Organization, Tedros Adhanom Ghebreyesus, offers this perspective: "As things stand, all hypotheses must remain on the table, including zoonotic spillover and lab leak. We continue to appeal to China and any other country that has information about the origins of COVID-19 to share that information openly, in the interests of protecting the world from future pandemics."
Paul's claims about Fauci's notes
Paul alleges the notes show Fauci's private consideration of the lab leak theory, while he publicly supported the natural origins theory.
On Paul's website, he points to Fauci's entry from Feb. 1, 2020, detailing a conference call between Fauci and prominent scientists.
In his notes, Fauci writes "there was not total agreement" about the virus' origins during the call.
Later in his entries, however, Fauci writes he "is almost certain that the virus evolved naturally from a species jump, even though… I keep an open mind about the possibility of a lab leak," and "that just because two alternatives are possible that does not mean that they are equally probable."
Many scientists say this thought process reflects how their consensus changed as the understanding of COVID-19 evolved.
Felicia Goodrum, a virologist at Dartmouth College who spoke to NPR on Monday from the American Society for Virology meeting in Minneapolis, says the questions in the early days of the pandemic about the lab leak were "normal scientific questioning," when scientists knew very little about how the virus spread.
"I think that's what we acknowledge that Fauci was doing, that there's of course a plethora of unanswered questions," she said of the early days of the pandemic. Now, though, she says those questions are presented as "some sort of signal of guilt that they knew that this was happening."
Gigi Gronvall, a biosecurity expert and immunologist, similarly says these kinds of questions are part of scientific exploration.
"It's not unusual that people would be entertaining a variety of opinions or thinking about a lot of different theories and holes in their theories as they go forward," she says. "That's kind of what science is all about."
Joseph Kim contributed to this report.
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