When she succeeded Anthony Fauci as the director of the National Institute of Allergy and Infectious Diseases, Jeanne Marrazzo felt that she'd landed "probably the most important infectious-disease job in the world," she told me. After decades of working in academia, she now had the power to influence, nationwide, the science she knew best-overseeing 4,500 employees at a $6.5 billion institute, the second largest by budget at the National Institutes of Health, the world's largest public funder of biomedical research.