ABOVE: NIH Director Francis Collins receives his first dose of the Moderna COVID-19 vaccine on December 22, 2020.

Francis Collins, a physician and geneticist, was appointed as the 16th director of the National Institutes of Health in 2009 by then-President Barack Obama; his appointment was unanimously confirmed by the Senate, and he continued to lead the agency under presidents Donald Trump and Joe Biden. On Tuesday, the agency announced Collins will be stepping down by the end of the year.

In the NIH press release, Collins says it’s simply time: “It has been an incredible privilege to lead this great agency for more than a decade. . . . I fundamentally believe, however, that no single person should serve in the position too long, and that it’s time to bring in a new scientist to lead the NIH into the future.”

According to NPR, Collins has served longer than any other presidentially appointed NIH director. Jennifer Zeitzer, head of public affairs at the Federation of American Societies For Experimental Biology (FASEB), tells NPR that Collins is “beloved on Capitol Hill,” in part because of his ability to “clearly explain what NIH is doing” to lawmakers.

During Collins’s tenure at NIH, the agency’s budget grew by 38 percent—a testament to its bipartisan Congressional support—and it launched numerous ambitious projects, including the BRAIN initiative and the Cancer Moonshot. “He’s been a strong leader. He’s gotten the resources needed to make the NIH the envy of the world to lead in certain scientific areas, without question,” Victor DiRita, chair of the Department of Microbiology & Molecular Genetics at Michigan State University, tells NPR.

Collins has also been lauded for his leadership during the coronavirus pandemic. He has been a staunch advocate for the COVID-19 vaccines, telling ABC’s George Stephanopoulos in August that he was “glad to see” requirements for vaccination put forward by President Biden. Collins also helped launch ACTIV, a project to coordinate clinical trials for antivirals and other COVID-19 treatments.

Additionally, Collins has been vocal in promoting diversity and inclusion in science. He announced in 2019 that he would not serve on all-male speaking panels because “Too often, women and members of other groups underrepresented in science are conspicuously missing in the marquee speaking slots at scientific meetings and other high-level conferences.” James E.K. Hildreth, president of Meharry Medical College in Nashville, tells The Washington Post in an email that Collins’s “courageous apology for long-standing racial bias in awarding of NIH grants and the major initiatives he has launched at NIH to eliminate racial bias in biomedical research funding represent fitting capstones to his legacy as NIH director.”

Collins has not been without controversy. The animal rights activist group People for the Ethical Treatment of Animals (PETA) called for his resignation and even protested at his home because of the agency’s continued funding of animal research under his leadership. And as an outspoken born-again Christian, his efforts to reconcile religion and science have not always gone over well: “some of my scientific colleagues argue that it’s totally inappropriate for a scientist to write about religion, and we already have too much faith in public life in this country. And then I get some very strongly worded messages from fundamentalists who feel that I have compromised the literal interpretation of Genesis 1 and call me a false prophet,” he told science journalist John Horgan in a 2006 interview republished by Scientific American in 2020. The same year he did the interview, Collins’s best-selling book The Language of God: A Scientist Presents Evidence for Belief was published. Collins founded the BioLogos Foundation, a group that sees evolution as God’s master plan, in 2009, and in 2020, he was awarded the $1.4 million Templeton Prize for his “integration of faith and reason.”

Prior to joining the NIH, Collins directed the National Human Genome Research Institute (NHGRI) from 1993 to 2008, where he oversaw the Human Genome Project. According to the NIH announcement, he will continue to lead a research laboratory there focused on genetic approaches to treating type 2 diabetes and Hutchinson-Gilford progeria syndrome, which involves rapid, premature aging.

According to the Post, no decision has been made as to who will fill in for Collins until Biden nominates and the Senate confirms a successor.