Newly released diary entries Republican lawmakers say were written by Dr. Anthony Fauci – the country's leading infectious disease specialist during the COVID-19 pandemic – chronicle Fauci's daily life between December 2019 and December 2022.
The over 1,100 pages of 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.
Sen. Rand Paul, R-Ky., 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.
This was all in advance of Wednesday's Senate hearing, where Fauci will testify.
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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 from a Chinese laboratory.
Paul chairs the Senate Homeland Security and Governmental Affairs Committee, and subpoenaed Fauci as the latest move in the pair's public disagreement about the origins of coronavirus.
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."
What Fauci's notes reveal
At first glance, Fauci's notes show him dealing with his increasing fame: including references to new security details, police guarding his home, celebrity encounters and "becoming an international celebrity" himself. The notes have the sentence fragments and typos of someone quickly recording their thoughts.
"Big front page article abut me appeared in the Washington Post," Fauci writes on May 21, 2020. "Very flattering. The situation with my national and international fame is explosive and really unimaginable. It is not hyperbole to say that today I am the most famous and talked about person in the country and one of the most recognizable peson in the world."
But the entries also show Fauci reacting with increasing alarm to case counts and the death toll and wrestling with questions about how the virus spread.
Consensus for natural origin
The current scientific consensus is that the virus is likely natural in origin. That means many scientists think the available data suggests COVID-19 started when someone in China was infected by an animal carrying the virus.
However, another theory popular with some researchers and President Donald Trump suggests SARS-CoV-2, the virus which causes COVID-19, spread from a Chinese government lab in Wuhan that was working with bat coronaviruses.
Paul alleges Fauci's notes show he covered up evidence supporting this "lab leak" 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."
The 'lab leak' theory and 'gain-of-function' controversy
The focus of the lab leak theory is the Wuhan Institute of Virology in China.
Part of the ongoing controversy has been whether a U.S. nonprofit helped the Wuhan Institute facilitate what's known as "gain-of-function" research that some believe led to the pandemic.
This kind of research involves experimenting with viruses and other pathogens in ways that give them new abilities. Often, this can help researchers better understand how the viruses work, or how they might become more dangerous or transmissible. The field has long been controversial because of the potential for dangerous pathogens to spill out of labs and cause a pandemic.
The group in question was a U.S. nonprofit called EcoHealth Alliance that researched bat coronaviruses. This included a years-long project in China, which EcoHealth ran in collaboration with the Wuhan Institute of Virology.
At the end of April 2020, the U.S. government stopped funding the project.
Many experts disagreed with the decision, saying that work was vital to preventing the next major coronavirus outbreak. The nonprofit's president at the time, Dr. Peter Daszak, said terminating coronavirus research posed a threat to national security and public health.
In January 2025, the U.S. Department of Health and Human Services (HHS) cut off all funding for EcoHealth and Daszak.
President Trump also restricted funding for gain-of-function research with an Executive Order in May 2025, and on Tuesday the U.S. Department of Health and Human Services (HHS) released a policy it says will establish more oversight for this kind of research.
What does the evidence say?
The Trump administration 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.
But as information evolved, scientists cast doubt on what came to be known as the lab leak theory. NPR's Geoff Brumfiel and Emily Kwong spoke to 10 leading scientists in 2020 who all believed the virus spread from animals to humans. They said their analyses of the virus showed no signs of human genetic modification, and that it infected people in a way scientists had never seen before — making laboratory engineering unlikely.
The following year, in February 2021, a joint investigation between China and the World Health Organization (WHO) similarly concluded that COVID-19 likely started in bats and made its way into humans via another animal.
At the time, however, the WHO Director-General Dr. Tedros Adhanom Ghebreyesus criticized the report, saying the team hadn't done enough work to completely rule out the lab leak theory.
U.S. government agencies continued to investigate the pandemic's origins in the following years.
In August 2021, U.S. intelligence agencies failed to reach a firm conclusion — and remained divided on the origins of COVID-19.
In 2023, the U.S. Department of Energy concluded, "with low confidence," COVID-19 originated from a lab leak. This was in direct conflict with many scientists who study the origins of pandemics, who said much of the evidence still pointed to a natural origin.
A Republican-led Select Subcommittee on the Coronavirus Pandemic concluded in December 2024 that a lab leak was the most likely explanation for SARS-CoV-2. They also suggested NIH funds contributed to gain-of-function research at the Wuhan Institute of Virology.
A plea for open minds and preparation
Some scientists say there is simply not enough information to make a firm conclusion about how the outbreak began.
"In my view it's important to keep investigating this question with an open mind while also proactively taking steps to minimize the risks of both future research-related and zoonotic outbreaks," evolutionary virologist Jesse Bloom wrote in an email to NPR.
Goodrum says the focus on Fauci's stance may erode public trust in research.
"I think they're trying to sow distrust in science and scientists," she says.
She says many virologists are concerned that funding cuts and the ongoing tension regarding the pandemic's origins are already hindering research focused on preventing the next pandemic.
"We are less safe. We are less prepared for a pandemic right now than we were in 2019," says Goodrum. "And this is terrifying to all of us."
Joseph Kim contributed to this report.
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