The White House on Wednesday removed Centers for Disease Control and Prevention Director Susan Monarez, saying the agency’s first Senate-confirmed chief was “not aligned” with President Donald Trump’s Make America Healthy Again agenda. Monarez, who had held the post for barely four weeks, is contesting the decision; her lawyers argue she can be dismissed only by the president himself. Health and Human Services Secretary Robert F. Kennedy Jr. had pressed Monarez to endorse sweeping changes to vaccine policy and to fire senior staff, according to people familiar with the talks. Monarez resisted, calling the directives unscientific and potentially illegal. Kennedy said the CDC suffers from deep “malaise” and must execute the administration’s priorities. Within hours of the firing, Chief Medical Officer Debra Houry, immunization chief Demetre Daskalakis, zoonotic-disease director Daniel Jernigan and data chief Jennifer Layden quit and were escorted from the CDC’s Atlanta campus. Hundreds of employees later staged a walkout in support of the departing leaders, leaving the nation’s top public-health agency effectively leaderless. An administration official said Kennedy’s deputy, Jim O’Neill, will serve as acting director while Trump selects a permanent nominee. Senate Health Committee Chairman Bill Cassidy and other lawmakers called for oversight hearings, and Kennedy is scheduled to testify before the Senate Finance Committee on Sept. 4. The upheaval follows Kennedy’s earlier dismissal of the CDC’s vaccine advisory panel and the FDA’s decision this week to limit updated Covid-19 shots mainly to older adults and high-risk patients. Public-health groups warned that the leadership vacuum and continued political interference could undermine the CDC’s ability to respond to infectious-disease threats.