Marston worked for McKinsey & Company and at the Bill & Melinda Gates Foundation as a program officer and special assistant. She then studied internal medicine at Brigham and Women's Hospital. In 2013, Marston joined National Institute of Allergy and Infectious Diseases (NIAID). She has experience in outbreak response, including Zika virus and Ebola. Marston served as a medical officer and policy advisor for global health and pandemic preparedness at NIAID. On April 15, 2020, Marston was the inaugural speaker at the NIH Intramural Research Program's new COVID-19 scientific interest group. Her presentation was titled "The Biomedical Research Response to COVID-19: A View from NIAID." In 2022, Marston joined the US Food and Drug Administration as Chief Medical Officer. She succeeded Janet Woodcock.
