The Centers for Disease Control and Prevention (CDC) official tasked with overseeing the nation’s vaccine policy resigned from his post Wednesday, shortly after the White House fired the agency’s director.

Demetre Daskalakis, director of the CDC’s National Center for Immunization and Respiratory Diseases, cited his philosophical differences with Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. that “challenge my ability to continue in my current role at the agency and in the service of the health of the American people,” adding, “Enough is enough.”

“I am unable to serve in an environment that treats CDC as a tool to generate policies and materials that do not reflect scientific reality and are designed to hurt rather than to improve the public’s health,” he wrote in his resignation letter, which he also posted on social media.

Daskalakis pointed to the recent change in the immunization schedule for children and pregnant women and said, “The data analyses that supported this decision have never been shared with CDC despite my respectful requests to HHS and other leadership.”

Similarly, the former vaccine official said the “frequently asked questions” document that HHS circulated to accompany the policy change was written “without input from CDC subject matter experts and that cited studies that did not support the conclusions that were attributed to these authors.”

“Having worked in local and national public health for years, I have never experienced such radical non-transparency, nor have I seen such unskilled manipulation of data to achieve a political end rather than the good of the American people,” he wrote.