Health Secretary Robert F. Kennedy Jr. said Thursday his top deputy, Jim O’Neill, will serve as the acting head of the Centers for Disease Control and Prevention, after the White House abruptly fired CDC Director Susan Monarez less than a month after she was confirmed by the Senate. Monarez is challenging her dismissal. O’Neill is a biotech investor who has worked for the far-right billionaire Peter Thiel and has previously served as a speechwriter in the George W. Bush administration. He has no formal training in medicine. The New York Times is reporting that the Trump administration fired Monarez after she declined to fire agency leaders or to accept all recommendations from a vaccine advisory panel stacked by RFK Jr. with anti-vaccine activists. Meanwhile, staff at CDC’s headquarters in Atlanta staged a mass walkout Thursday to support senior officials who stepped down in protest of RFK Jr.’s actions. Infectious disease experts Demetre Daskalakis, Daniel Jernigan and Debra Houry thanked colleagues and promised to keep fighting to protect public health. Dr. Demetre Daskalakis: “Whether it’s in preventing overdose, chronic disease, stopping Ebola at its source rather than letting it come to this continent, you are the people that protect America.” Dr. Daniel Jernigan: “And what makes us great at CDC is following the science. And so let’s get the politics out of public health.” Dr. Debra Houry: “We need Congress to intervene. We need our appropriations. We need to follow science. We need to have ethics back.”