Fauci joined the National Institutes of Health (NIH) as an autoimmune-disease researcher after getting his doctorate from Cornell University.
He's spent more than half his life working in the public-health sector.
Fauci took over the top position at NIAID in 1984. The institute has an annual budget of nearly $6 billion and manages the prevention, diagnosis, and treatment of infectious diseases like HIV/AIDS, measles, and tuberculosis in the US.
NIAID also supports research on autoimmune disorders like asthma and allergies and handles oversight of emerging diseases such as Ebola and Zika.
When Fauci took over NIAID, the world was in the throes of the HIV/AIDS crisis. He was one of the leading architects of the President's Emergency Plan for AIDS Relief, a program credited with saving millions of lives.
Fauci's research has been pivotal in understanding how HIV destroys the body's immune system. He played a critical role in developing treatments that enable HIV-positive people to live long and active lives.
George W. Bush awarded Fauci the Presidential Medal of Freedom — the highest honor given to a civilian — in 2008 because of his role in creating the PEPFAR program.
Fauci has also won the Presidential National Medal of Science and been given 45 honorary doctoral degrees from universities in the US and abroad.
He won the Robert Koch Gold Medallion, an international award for "accumulated excellence in biomedical research" in 2013.
President George H. W. Bush asked Fauci to be head of the NIH in 1989, but Fauci refused, saying that his work at NIAID was more important.
As a researcher, Fauci has been the author, co-author, or editor of more than 1,300 scientific publications.
Fauci was the 41st-most cited researcher of all time based on Google Scholar citations, according to a 2019 analysis.
He ranks eighth out of more than 2.2 million immunology authors in terms of his citation counts in the last 40 years.
Fauci also worked on the response to the anthrax threat in the US following the September 11 attacks.
After 9/11, the US prepared for a potential biological attack as deadly anthrax packages flooded the offices of government workers and members of the media. Fauci kickstarted a NIAID research program to work on treatments and vaccines for infectious agents that could be used by bioterrorists.
His expertise and experience were also critical during the Ebola outbreak between 2014 and 2016, and the Zika outbreak that started soon thereafter.
Fauci assisted with the creation of public policy around Ebola, and he worked to reassure Americans of their safety.
Ned Price, a top National Security Council aide under the Obama administration, tweeted Thursday: "During the Ebola outbreak, we couldn't get enough of NIH's Dr. Fauci because no one knew more or could deliver it with more authority or experience. Muzzling Dr. Fauci is an effort to muzzle fact and science when it's needed most."
Fauci told Smithsonian Magazine in 2016 that we've learned the same lesson during every infectious-disease outbreak: "You've got to be prepared. You have to have good surveillance. You have to have good diagnostics."
He added: "You have to be able to move quickly. And we've shown that when you do that, you get good results."
Fauci has approached the new coronavirus outbreak in the same way.
Fauci's work has saved the lives of millions of men, women, and children across the world, according to the American Academy of Achievement.
The Academy cited Fauci's legacy of leadership in public health and research into HIV/AIDS therapies.
