Deputy Health and Human Services Secretary Jim O’Neill has been named acting director of the Centers for Disease Control and Prevention (CDC), Health Secretary Robert F. Kennedy announced Friday in a letter to staff.
O’Neill, a former Silicon Valley investor with ties to Peter Thiel, previously served in the George W. Bush administration, overseeing food regulation and emergency response.
He replaces Dr. Susan Monarez, who was fired earlier this week, triggering a wave of high-profile resignations at the CDC. Employees gathered Thursday to honor several departing officials, including former chief medical officer Dr. Debra Houry and vaccine chief Dr. Demetre Daskalakis.
🚨 BREAKING: President Trump has just tapped RFK Jr.’s top deputy, Jim O’Neill, as Acting Director of the CDC
— Nick Sortor (@nicksortor) August 28, 2025
This comes just a day after Trump FIRED CDC Director Susan Monarez, who resisting the pullback of COVID vaccines pic.twitter.com/ugjjWoO2vH
O’Neill, who recently toured the CDC with Kennedy after a deadly shooting at the agency’s campus, has pledged reforms, more transparency, and support for the CDC’s vaccine schedule. He told senators he would focus on prevention, “gold standard science,” and reforming outdated rules to strengthen public trust.
