Health Secretary Robert F. Kennedy Jr. has fired a top official with the National Institutes of Health who blew the whistle on internal clashes over vaccine research in the early months of the Trump administration.

On Wednesday, Dr. Jeanne Marrazzo received a letter from Kennedy — which CBS News reviewed — informing her that her role leading NIH’s National Institute of Allergy and Infectious Diseases, or NIAID, had been terminated. He did not cite a cause beyond his constitutional authority to do so. Last month, in an exclusive interview with CBS News, Marrazzo said she had been silenced when she and her colleagues pushed back against NIH officials appointed by President Trump who questioned the importance of childhood flu vaccines and canceled long-running clinical trials.