Fauci’s tenure as director of the infectious-diseases institute made him an adviser to seven presidents and put him on the front lines of every modern-day scourge, including AIDS, the 2001 anthrax scares, Ebola, Zika and the coronavirus pandemic. During the nearly four decades Fauci led the agency, it grew from a little-known institute with a $350 million annual budget to a globally recognized powerhouse with a budget exceeding $6 billion.

“Because of Dr. Fauci’s many contributions to public health, lives here in the United States and around the world have been saved,” said Biden, who as vice president worked with Fauci on the nation’s response to Ebola and Zika during the Obama administration. “Whether you’ve met him personally or not, he has touched all Americans’ lives with his work.”

While Fauci is one of the most cited researchers of all time and has been widely known in scientific circles for decades, it was the coronavirus pandemic that catapulted him to worldwide fame — and ignited criticism from some Republican politicians and threats from the public.

Anthony Fauci is up against more than a virus

Fauci, who spoke about his impending departure in a wide-ranging interview with The Washington Post, had been a lightning rod before, most notably during the early days of the AIDS crisis when activists clamored for a swifter government response as they watched friends die. But the coronavirus pandemic arrived in a strikingly different era, with social media pouring fuel on the criticism and baseless conspiracy theories leveled at Fauci and others presiding over the federal government’s response.

The veteran scientist acknowledged missteps: In the early weeks of the pandemic, Fauci and other government scientists said Americans did not need to wear masks, which President Donald Trump seized on toward the end of his presidency to criticize Fauci and to question his expertise. And, like many other disease detectives, Fauci did not recognize early on that asymptomatic people were prime spreaders of the virus.

Fauci conceded that he and other government scientists were wrong about masks in the beginning. He said they were worried about having enough face coverings for overwhelmed health-care workers and did not yet see evidence that masks were effective in preventing infection outside of hospitals, which later became clear, particularly as scientists realized the virus was airborne.

Those factors “led the surgeon general of the United States, the CDC and me to say, right now, you really don’t need to wear a mask and all of a sudden, it became Tony Fauci is the mask guy,” Fauci said. “Since I am the primary target of the far right, when the far right says you got it wrong, it isn’t that everybody got it wrong — it’s that Tony Fauci got it wrong.”

The last 2½ years marked some of the most rewarding and challenging times of his career, Fauci said. His public contradictions of Trump over unproven covid-19 treatments and the threat posed by the pandemic and his advocacy of mitigation measures made Fauci a villain to the political right.

“It was one of the most important challenges that we have had to face, and I believe my team and I — and let history be the judge of that — have made a major contribution,” Fauci said. “We didn’t do it alone, but we played a major role in the development of the vaccines that have now saved millions of lives.”

But Fauci said the pandemic, which has claimed more than 1 million lives in the United States, proved “extremely stressful.”

He attributed that to the combination of dealing with a novel virus that has shown a remarkable propensity to infect people and mutated with breathtaking speed and the politically charged environment in which the government had to run a response. That, coupled with his fame and the attention given to his public statements, made making mistakes and communicating changing scientific guidance to the public immensely harder, he said.

In the interview, Fauci said he wanted to step down from his government post while still healthy, energetic and passionate about his field and enthusiastic about the next stage of his career.

He also reflected on anti-science sentiments that have proliferated, mistakes he and other scientists made during the pandemic, deep national divisions infecting politics that have put democracy at risk, and lessons learned from the government and national response to the coronavirus.

Fauci emphasized that he is not exiting the public square. He said he hopes to teach, lecture, write — perhaps a book, along with essays and other types of writing — and use his experience to inspire and teach a younger generation of scientists.

“I love everything about this place. … But even with that, I said I’m going to have to leave some time,” Fauci said. “I don’t want to be here so long that I get to the point where I lose a step.”

White House Chief of Staff Ron Klain said the first phone call he made after Biden was declared president-elect — at Biden’s direction — was to ask Fauci to serve as chief medical adviser. When he served as Ebola czar in 2014 in the Obama administration, Klain worked with Fauci.

“This is someone who’s given his life to save lives and serve this country,” Klain said.

Fauci, who earns $480,654 a year, considered retiring at the end of Trump’s term, he said. But when Biden called during the presidential campaign and asked whether he would serve in a potential Biden administration, Fauci reconsidered. He figured he would stay at least a year to help shepherd the country through the pandemic just as vaccines were becoming available. In the end, the virus proved far more daunting to control than anticipated, and Fauci will have served nearly two years with Biden.

Still, Fauci said, with an arsenal of vaccines and treatments and increasing immunity through shots and exposure to the virus, the nation is approaching a moment of equilibrium at which it can live with the virus.

An interim successor is expected to be named before Fauci departs, and NIH will conduct a national search for Fauci’s replacement.

Fauci assumed leadership of the National Institute of Allergy and Infectious Diseases as HIV was infecting thousands of gay men, nearly all of whom died because no treatments existed. A few years earlier, Fauci had been developing curative therapies for inflammatory diseases and saw many of his patients who were supposed to die doing surprisingly well. But in the 1980s, Fauci changed the direction of his lab to focus on the emerging disease affecting primarily gay men. Suddenly, almost all of his patients were dying, and there was nothing he could do to stop it.

“To have every one of my patients die was really, quite frankly, traumatic,” Fauci said. “It was extremely frustrating when you’ve been trained to be a healer, and you’re doing nothing but putting Band-Aids on hemorrhages, metaphorically speaking, when you’re treating HIV.”

The Reagan administration for years paid little attention to the crisis, enraging gay activists who felt the government was doing nothing to stop them from getting sick and dying. Fauci and his lab had been studying AIDS for about three years by the time he became the institute’s director, but they had made little progress on a treatment.

By the late 1980s, gay activists had organized to bring global attention to the AIDS crisis. NIH and the Food and Drug Administration were targets of their demonstrations and demands that government agencies accelerate research and new-drug approval and access.

AIDS activists wanted a voice in clinical trial design and for patients to have access to experimental drugs. For years, scientists and government officials — including Fauci — refused to change the research process to allow patients access to medications out of fear it would compromise scientific integrity. Activists staged “die-ins” in front of Fauci’s office, chanting “Fire Fauci!”

Fauci said he eventually realized the activists were right — the process needed to change. And he befriended the activists, some becoming close friends and advisers. Fauci advocated for the “parallel track approach” that allows patients to access experimental medication while a randomized controlled trial unfolds separately to determine a drug’s efficacy. Years later, under President George W. Bush, Fauci was one of the architects of PEPFAR, the multibillion-dollar global HIV/AIDS program that has saved millions of lives. Bush awarded Fauci the Presidential Medal of Freedom in 2008.

Fauci could usually find common ground with his adversaries and a way to work with them. That changed with the coronavirus pandemic.

Even as they sometimes employed aggressive tactics, AIDS activists were correct that the clinical trial process for drugs was too rigid and needed to change, Fauci said. But he said his opponents during the coronavirus pandemic have been engaged largely in arguments devoid of science.

“The situation with the political divisiveness [with covid-19] was totally different because you had the complete unreality of stating that drugs worked when there was no evidence they did,” Fauci said. “The leader of the country is saying, ‘Oh, don’t worry, it’s going to disappear tomorrow.’ … I felt I had an obligation to the country to be the person who speaks for science and speaks for the truth.”

‘You become the villain’

If Republicans win control of the House in November’s elections, several members have said they will launch investigations into Fauci. Rep. Jim Jordan (R-Ohio) and Sens. Rand Paul (R-Ky.) and Roger Marshall (R-Kan.) have come after Fauci with particular ferocity and propagated baseless claims and conspiracy theories about him.

Fauci said he is not concerned with potential investigations and has not given much thought about how he might deal with them.

“There is nothing that I cannot defend,” Fauci said. “I can respect disagreement, but there’s a big difference between disagreement and investigating somebody for doing something terrible.”

The attacks from the right have resulted in threats on Fauci’s life. A man who sent emails to Fauci threatening to kill him and his family was sentenced this month to more than three years in prison.

The barrage of threats prompted the government to assign Fauci a security detail, which he is likely to continue needing after he leaves his post.

“I had to oppose a president of the United States. That is not the easiest thing in the world to do, but I did it,” Fauci said.

Until Trump, Fauci managed to get along with the presidents he advised. He has long insisted he is a “nonpolitical person” and speaks only to science.

Since he first visited the White House to advise President Ronald Reagan, Fauci said, he has lived by advice from a friend who had advised President Richard M. Nixon. Each time you walk into the White House, the advice went, tell yourself it may be the last time. You may have to tell the president or a high-ranking official something they don’t want to hear — an inconvenient truth — and they may never want to speak with you again. Or they may respect that you told them the truth and want you back.

Six presidents wanted Fauci to come back. Trump did not.

In the first weeks of the pandemic in 2020, Fauci seemed to strike a delicate rapport with Trump. But as Trump started seizing on so-called cures in a desperate attempt to persuade people that the pandemic was nearing an end, Fauci began publicly contradicting the temperamental president. While Trump insisted hydroxychloroquine was a promising treatment, Fauci repeatedly said there was no evidence it worked.

Trump initially embraced a recommendation from Fauci and the president’s coronavirus response coordinator, Deborah Birx, to extend guidance for a nationwide shutdown. But Trump then abandoned all mitigation measures as the virus continued to rage through summer and fall 2020 before vaccines and treatments became available. Fauci continued to advise that people wear masks and socially distance even after many, particularly Republicans, had grown weary of restrictions, making him a boogeyman to the right. His embrace of vaccine mandates in 2021 calcified that view.

Trump ultimately turned on Fauci, resulting in a remarkable public breach in July 2020 when White House officials released an opposition-style memo on every time they believed Fauci had been wrong about the pandemic.

“I was put in a very unusual circumstance where the country was scared, they really wanted someone who was steady and honest and showed integrity and stuck with the facts, and I became the symbol of that,” Fauci said. “And when you become a symbol for a certain segment of people, the people against that, you become the villain to them.”

Some of Fauci’s goals have proved elusive. Earlier in his years as director of the infectious-diseases institute, he said he did not want to leave without a major breakthrough on an HIV vaccine. While he said that goal is in reach, it won’t happen before he steps down — and maybe not for a long time after.

Then, there are the humbling lessons from the past two-plus years: Don’t underestimate what an emerging outbreak can do. With HIV and the coronavirus, scientists initially thought only people with symptoms were infected, failing to recognize the potential of asymptomatic spread and missing the scope of both pandemics. Understanding asymptomatic spread earlier would have dramatically changed the government’s response to both crises.

Fauci said he has never seen the country so deeply polarized. Even as he worries about the nation’s direction, Fauci maintains hope the country can recover from its bout of political acrimony: “I believe that, ultimately, the better angels in our country are going to prevail.”