Health and Human Services Secretary Robert F. Kennedy Jr.’s leadership is described as unprecedented by nine former directors and acting directors of the Centers for Disease Control and Prevention, who expressed their concerns in a critical guest essay for The New York Times.

The essay, titled “We Ran the C.D.C.: Kennedy Is Endangering Every American’s Health,” was published shortly after President Donald Trump dismissed CDC director Susan Monarez. Monarez, through her legal representatives, claimed she resisted approving irresponsible and non-scientific directives.

Kennedy’s leadership, marked by his involvement in Monarez’s dismissal, is unprecedented according to the former directors, indicating actions at the agency that have no parallel in history.

The essay enumerated various concerns, critiquing Kennedy for promoting unproven treatments while minimizing the importance of vaccines. The former directors accused Kennedy of halting investments in significant medical research, leaving the country vulnerable to future health crises. He allegedly replaced qualified experts on health advisory committees with individuals who hold his controversial views and halted U.S. support for global vaccination initiatives, citing dubious research and issuing erroneous statements.

HHS and CDC spokespersons did not immediately respond to requests for comment.

Signatories of the essay include William Foege, William Roper, David Satcher, Jeffrey Koplan, Richard Besser, Tom Frieden, Anne Schuchat, Rochelle P. Walensky, and Mandy K. Cohen. These individuals have served across various Democratic and Republican administrations since the late 1970s, including Trump’s tenure.

Monarez’s dismissal coincided with escalating tensions related to a pivotal vaccine committee that Kennedy allegedly undermined, as reported by NBC News. The secretary had removed committee members and installed vaccine skeptics. Monarez was concerned she would be compelled to endorse vaccine recommendations lacking scientific backing, leading to a rapid leadership departure from the CDC following her dismissal.

“We are worried about the wide-ranging impact that all these decisions will have on America’s health security,” the former directors wrote in their guest essay.

“During our respective C.D.C. tenures, we did not always agree with our leaders, but they never gave us reason to doubt that they would rely on data-driven insights for our protection, or that they would support public health workers,” they added.

The former directors urged Congress to “exercise its oversight authority” over HHS and called on state and local governments and philanthropic givers to “fill funding gaps where they can.”

“The men and women who have joined C.D.C. across generations have done so not for prestige or power, but because they believe deeply in the call to service,” they wrote in conclusion. “They deserve an H.H.S. secretary who stands up for health, supports science and has their back. So, too, does our country.”