Jim O'Neill, a deputy of Health and Human Services Secretary Robert F. Kennedy Jr., has been selected to serve as acting director of the US Centers for Disease Control and Prevention (CDC), the White House confirmed.
O'Neill's appointment on Thursday follows the termination of CDC Director Susan Monarez, who was removed from her position less than a month after her Senate confirmation.
White House spokesperson Karoline Leavitt said Monarez was not aligned with US President Donald Trump's health agenda.
"She was not aligned with the president's mission to make America healthy again, and the secretary asked her to resign. She said she would, and then she said she wouldn't. So, the president fired her, which he has every right to do," she told reporters.
Leavitt emphasised presidential authority in personnel decisions, adding "the president has the authority to fire those who are not aligned with his mission."
O'Neill was sworn in on June 9 as deputy secretary of the US Department of Health and Human Services (HHS), overseeing agencies including the National Institutes of Health, the Food and Drug Administration (FDA), the CDC, the Centers for Medicare and Medicaid Services and the Administration for Children and Families.
He previously served at the HHS from 2002 to 2008. From 2007 to 2008, he served as Principal Associate Deputy Secretary, leading FDA reforms that overhauled food safety regulations and implemented the FDA Amendments Act to improve the safety of drugs and medical devices.
O'Neill holds degrees from Yale University and the University of Chicago and has three children.
Monarez, a microbiologist with a PhD, was confirmed by the Senate on July 29 and sworn into office by Kennedy on July 31. Her brief leadership occurred during significant upheaval at the CDC, including policy changes and staff cuts under Kennedy's oversight.
Monarez's termination triggered additional departures within the CDC leadership structure. Several senior officials submitted resignations following her dismissal, citing concerns over the agency's direction under Kennedy's oversight and disagreements with the administration's public health approach.
