President Trump nominated Dr. Monarez as CDC Director after withdrawing his previous choice, Dave Weldon, M.D., after it became apparent that he would not be able to secure the votes in Senate required for his confirmation. She stepped down as Acting Director of CDC, a role she assumed in January 2025, once she was nominated for Director.

Dr. Monarez said in a Senate confirmation hearing that her first priority is restoring trust in CDC by holding leadership publicly accountable and relying on science-backed decision-making, per NPR. She also shared her intent to modernize public health infrastructure, and to improve disease outbreak response time and communication.

In her career, Dr. Monarez held positions at the U.S. Department of Homeland Security overseeing research portfolios, as well as in the White House Office of Science and Technology Policy and on the National Security Council, leading efforts to enhance the nation's biomedical innovation capabilities, including combating antimicrobial resistance (AMR), expanding the use of wearables to promote patient health, ensuring personal health data privacy, and improving pandemic preparedness. Per CDC, she has headed initiatives focused on the ethical use of artificial intelligence (AI) and machine learning to support improved health outcomes, novel approaches to addressing affordability and accessibility in healthcare, expanding access to behavioral and mental health interventions, ending the opioid epidemic, addressing health disparities in maternal morbidity and mortality, and improving the country's organ donation and transplantation programs.