Following the firing of former U.S. Centers for Disease Control and Prevention (CDC) Director Susan Monarez, Ph.D.—which played out in a social media showdown on August 27—Jim O’Neill, the Deputy Secretary of the U.S. Department of Health and Human Services (HHS), has been appointed CDC’s Acting Director (confirmed by Stat).

Dr. Monarez was nominated for CDC Director by President Trump and was just confirmed by the Senate in July.

In contrast to his ousted predecessor and CDC Directors who served before Dr. Monarez, Mr. O’Neill has no training in medicine or infectious disease science.

When Mr. O’Niell was named Deputy Secretary of HHS, Secretary Kennedy highlighted Mr. O’Neill’s “extensive experience in Silicon Valley and government.”

Prior to being sworn in as HHS Deputy Secretary, serving under Secretary Robert F. Kennedy Jr. (RFK Jr.), from 2007–2008, Mr. O’Neill was the HHS Principal Associate Deputy Secretary where he “led reforms at FDA to overhaul food safety regulations,” per HHS. After his first stint at HHS, Mr. O’Neill became a managing director of Clarium Capital, a global macro investment fund. He was also CEO the Thiel Foundation, which “funds nonprofits that promote technology and freedom,” and co-founded the Thiel Fellowship, which helped “launch the careers of young entrepreneurs who founded science and tech companies worth hundreds of billions of dollars.” More recently, Mr. O’Neill served as CEO of SENS Research Foundation.

Dr. Monarez’s departure from CDC was shortly followed by the resignation of three top CDC officials, including Dan Jernigan, M.D., Director of the National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), which is responsible for tracking foodborne illness outbreaks, zoonotic diseases, and antimicrobial resistance (AMR). Dr. Monarez’s refusal to fire Dr. Jernigan and two others at the request of Secretary Kennedy is said to be one of the reasons for her termination.

The sudden change in CDC leadership comes at an already tumultuous time for the agency, which has experienced significant workforce and budget cuts since the Trump Administration entered the White House, including the dismissal of more than 2,000 staffers.

Additionally, CDC funding cuts have affected the Foodborne Diseases Active Surveillance Network (FoodNet) surveillance program, which, in August, quietly slashed the number of foodborne pathogens monitored under the program from eight to two.