Top US infectious disease expert Anthony Fauci plans to step down from his post in December to “pursue the next chapter” of his career, he announced in a statement on Monday.

Fauci, 81, has led the National Institute of Allergy and Infectious Diseases (Niaid) since 1984. He has advised seven presidents, as far back as Ronald Reagan, on emerging infectious disease outbreaks that have plagued the nation, testifying before Congress and the World Health Organization on the HIV/Aids epidemic to Ebola to, most recently, the coronavirus pandemic.

In his statement, Fauci stopped short of saying precisely what his plans are. He pledged to pursue a new professional phase while he still had “energy and passion” for his field.

“I want to use what I have learned as Niaid director to continue to advance science and public health and to inspire and mentor the next generation of scientific leaders as they help prepare the world to face future infectious disease threats,” he said.

In a White House statement, Joe Biden thanked for Fauci for his decades of service. The president also praised Fauci as a “dedicated public servant, and a steady hand with wisdom and insight honed over decades at the forefront of some of our most dangerous and challenging public health crises”.

“Because of Dr Fauci’s many contributions to public health, lives here in the United States and around the world have been saved,” Biden said.

Under George W Bush, Fauci worked as one of the principal architects of the President’s Emergency Plan for Aids Relief, a global public health initiative launched in 2003 aimed at expanding access to therapies to curtail the HIV/Aids epidemic, long credited as a historic effort that saved millions of lives.

He won the Presidential Medal of Freedom in 2008 for his “determined and aggressive efforts to help others live longer and healthier lives” in the fight against the HIV/Aids epidemic, even as he clashed with activists early on.

As the deadly coronavirus spread throughout the world in March 2020, Fauci – whose calm, measured presence drew admiration – emerged as the face of the US’s response to the pandemic. He notably clashed with former president Donald Trump at the start of the crisis, along with congressional Republicans, over what the US response should be. Fauci advocated for more restrictions to suppress the virus, a stark contrast from the Trump administration’s approach to publicly downplay it in hopes of shielding economic markets from being affected.

Memorably, earlier this year, Fauci bluntly said he would quit if Trump managed to take the Oval Office back from Biden in the 2024 election. He previously indicated he would stay through Biden’s first term and leave by January 2025.