Hundreds of current and former Centers for Disease Control and Prevention employees staged a walkout outside the agency’s Atlanta headquarters on Thursday, the largest public protest in the CDC’s history. The demonstration, described by participants as a "clap-out," came one day after the Department of Health and Human Services said Director Susan Monarez "no longer leads" the agency—less than a month after her Senate confirmation. Monarez’s lawyers contend the dismissal is legally invalid because only President Donald Trump can remove a presidential appointee. They say she was pushed out for refusing to endorse what they called "unscientific, reckless directives," including efforts to purge vaccine advisers and cut core disease-tracking programs. Three senior officials—Chief Medical Officer Debra Houry, National Immunization Center head Demetre Daskalakis and Zoonotic Diseases chief Daniel Jernigan—resigned in coordinated fashion on Wednesday and joined the demonstration. Staff briefly left their posts to applaud the departing leaders before returning to work, while signs reading “Science First” lined the sidewalks. Health and Human Services Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, defended Monarez’s removal, citing a "deeply embedded malaise" at the agency. The shake-up follows Kennedy’s dissolution of the CDC’s vaccine advisory panel and comes amid budget and personnel cuts ordered earlier in Trump’s second term. The turmoil has drawn bipartisan concern on Capitol Hill. Senate Health Committee Chair Bill Cassidy urged postponement of an upcoming vaccine advisory meeting and called for oversight hearings, while ranking member Bernie Sanders pressed for a broader investigation into Monarez’s ouster and the CDC’s capacity to protect public health.