In late August 2025, a rumor spread online that the U.S. Centers for Disease Control and Prevention's (CDC) immunization chief, Dr. Demetre C. Daskalakis, stepped down from his post and published a resignation letter denouncing Health and Human Services (HHS) Secretary Robert F. Kennedy Jr.'s leadership. HHS oversees the CDC.
The rumor spread on platforms like X, Threads and Reddit. One post on Facebook had over 235,000 reactions as of this writing.
Daskalakis was, in fact, the CDC's director of the National Center for Immunization and Respiratory Diseases before he resigned on Aug. 28, 2025. He also posted his full, 1,200-word resignation letter on his X account and on his verified Instagram, indicating the letter's authenticity.
"After much contemplation and reflection on recent developments and perspectives brought to light by Secretary Robert F. Kennedy Jr., I find that the views he and his staff have shared challenge my ability to continue in my current role at the agency and in the service of the health of the American people," Daskalakis wrote in his letter.
Thus, we rate this claim true.
Archived versions of the CDC's website showed that the agency listed Daskalakis as its immunization chief on Aug. 28, 2025, before it updated the site on the same day to list Daskalakis' former position as "vacant."
According to a copy of Daskalakis' resume on Congress' website, he became acting director of the agency's National Center for Immunization and Respiratory Diseases in August 2023 before officially assuming the role in December 2023.
Why did Daskalakis resign?
Daskalakis, who previously served in former President Joe Biden's administration as the deputy coordinator of the White House's mpox response team, resigned
Pictures of CDC staff and supporters outside of the agency's headquarters in Atlanta, Georgia, cheering on Daskalakis, alongside his two colleagues who resigned, were available on Getty Images. The Associated Press also posted a live video of the rally; speeches from Daskalakis and his colleagues begin at 45:55.
Here are a few excerpts from Daskalakis' resignation letter, where he clearly stated that Kennedy's leadership and anti-vaccine policies pushed him to leave the CDC, particularly Kennedy's Aug. 27 announcement that the FDA would implement restrictions on 2025 fall COVID vaccines:
I am writing to formally resign from my position as Director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention (CDC), effective August 28, 2025, close of business.
[...]
After much contemplation and reflection on recent developments and perspectives brought to light by Secretary Robert F. Kennedy Jr., I find that the views he and his staff have shared challenge my ability to continue in my current role at the agency and in the service of the health of the American people. 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. The recent change in the adult and children's immunization schedule threaten the lives of the youngest Americans and pregnant people.
[...]
I have always been first to challenge scientific and public health dogma in my career and was excited by the opportunity to do so again. I was optimistic that there would be an opportunity to brief the Secretary about key topics such as measles, avian influenza, and the highly coordinated approach to the respiratory virus season. Such briefings would allow exchange of ideas and a shared path to support the vision of "Making America Healthy Again." We are seven months into the new administration, and no CDC subject matter expert from my Center has ever briefed the Secretary. I am not sure who the Secretary is listening to, but it is quite certainly not to us. Unvetted and conflicted outside organizations seem to be the sources HHS use over the gold standard science of CDC and other reputable sources. At a hearing, Secretary Kennedy said that Americans should not take medical advice from him. To the contrary, an appropriately briefed and inquisitive Secretary should be a source of health information for the people he serves. As it stands now, I must agree with him, that he should not be considered a source of accurate information.
[...]
Sincerely,
Demetre C. Daskalakis MD MPH (he/his/him)
Daskalakis also wrote about the harms he believed would be caused by Kennedy's overhaul of the Advisory Committee on Immunization Practices (ACIP), the group in charge of the CDC's vaccination recommendations. Kennedy, known for pushing anti-vaccine views, replaced the entire advisory committee in June. Many of the new panel members reportedly have a history of vaccine skepticism.
"The recent term of reference for the COVID vaccine work group created by this ACIP puts people of dubious intent and more dubious scientific rigor in charge of recommending vaccine policy to a director hamstrung and sidelined by an authoritarian leader," Daskalakis's letter said. "Their desire to please a political base will result in death and disability of vulnerable children and adults."
Finally, Daskalakis, a prominent gay health activist with a background in HIV prevention, cited the "recklessness of the administration in their efforts to erase transgender populations, cease critical domestic and international HIV programming, and terminate key research to support equity" as part of his decision.
Daskalakis' full letter can be found here.