RFK Jr. taps top health aide to lead CDC after ousting director

Jennifer A. Dlouhy, Rachel Cohrs Zhang and Jessica Nix, Bloomberg News on Aug 28, 2025

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WASHINGTON — The Trump administration is tapping a deputy of Health and Human Services Secretary Robert F. Kennedy Jr. as the acting director of the Centers for Disease Control and Prevention, after moving to oust the agency’s current head in a clash over vaccine policy.

Jim O’Neill, the Health and Human Services deputy secretary, was named the CDC’s acting director, according to an administration official. O’Neill couldn’t be reached for comment. CDC employees hadn’t been notified of his appointment as of Thursday evening, according to staff members who asked to remain unnamed discussing agency operations.

The move follows the firing of Susan Monarez just weeks into her tenure as the agency’s director. The contested dismissal occurred after a confrontation with Kennedy, when Monarez pushed back on his vaccine stance. Attorneys representing her said she was “targeted” because she “refused to rubber-stamp unscientific, reckless directives and fire dedicated health experts.”

The clash, plus the resignation of three other senior CDC leaders, has highlighted the turmoil at the agency. Kennedy, a longtime vaccine critic who has promoted unorthodox public health views, has moved to overhaul the nation’s immunization policies.

Kennedy, in an interview with Fox News on Thursday morning, said the CDC wasn’t sufficiently aligned with President Donald Trump’s agenda and needed to be overhauled, slamming policies it advocated during the COVID-19 pandemic.

Monarez’s firing came the same week that Trump moved to put his stamp on other institutions, seeking to fire Federal Reserve Governor Lisa Cook and Robert Primus, a Democrat from a federal agency weighing in on a major rail merger.

O’Neill previously worked at HHS from 2002 to 2008, then became managing director at Clarium Capital, a global macro investment fund, and was CEO of the Thiel Foundation. It’s unclear how closely O’Neill will conform to Kennedy’s efforts to remake immunization policy in the U.S., including the reconstitution of a key CDC panel that helps determine how vaccines are used in the country.

In a Senate hearing earlier this year, O’Neill said he’s “very much in favor of vaccines,” adding that “they’re one of the greatest public health interventions in human history.”

(Josh Eidelson contributed to this report.)