WASHINGTON, D.C.: Three senior officials at the U.S. Centers for Disease Control and Prevention resigned this week, citing deep concerns over changes to the agency's vaccine policy and advisory process under Health and Human Services Secretary Robert F. Kennedy Jr.

Debra Houry, Demetre Daskalakis, and Dan Jernigan said that they could no longer stay at the CDC after Kennedy replaced the long-standing Advisory Committee on Immunization Practices (ACIP) with hand-picked advisers, some of whom are known vaccine skeptics. The three officials said those advisers were issuing recommendations before reviewing data.

"For us, that's problematic," said Houry, who served as the CDC's chief medical officer. "As scientists, you should never know in advance what you want the data to show."

Daskalakis, who led the National Center for Immunization and Respiratory Diseases, added: "I'm a doctor, I took the Hippocratic oath that said ‘first, do no harm.' I believe harm is going to happen, and so I can't be a part of it."

Kennedy, a longtime critic of vaccines, has defended his policy changes as an effort to improve transparency and reduce industry influence. In June, he dismissed all members of the ACIP. He installed new advisers, including anti-vaccine activists Lyn Redwood and David Geier, who are listed in the HHS database as an "expert" and a "senior data analyst."

Jernigan, who directed the National Center for Emerging and Zoonotic Infectious Diseases, said he was pressured to review and revise established vaccine safety findings at their request. "I was told the requests were legally supported, and that was enough. But for me, that's just not enough," he said.

Neither Redwood nor Geier responded to requests for comment.

The departures came a day after CDC Director Susan Monarez was abruptly removed from her post. While the White House said she was fired, her attorneys called the move illegal. Houry said Monarez had tried to restore transparency by adding a federal official to ACIP and opening documents for public review, but HHS blocked her.

"She wanted to have engagement and transparency. Those things were not done," Houry said. "She was given feedback that those couldn't happen, and was called to a meeting with the secretary on Monday. For us, we knew that if our scientific leader couldn't make changes like that, we could no longer stay."

The resignations underscore growing discord inside U.S. public health agencies. Daskalakis said he believed Kennedy's aim was "to create chaos and more mistrust of vaccines, so that there is less demand … and then over time, they can demonstrate that there's less need" for federal support.

Medical organizations and several states have already begun issuing their own vaccine guidance ahead of the autumn respiratory illness season. Meanwhile, the FDA's decision this week to narrow eligibility for updated COVID-19 vaccines raised additional concerns about insurance coverage and public access.

The three officials said they had agreed to resign together. They gathered their belongings and spoke with staff before being escorted out of CDC headquarters in Atlanta.