The Centers for Disease Control and Prevention (CDC) has five key leaders who are openly accusing the Department of Health and Human Services (HHS), led by Secretary Robert F. Kennedy Jr., of using public health as a weapon and endangering lives.

In a single day, four prominent leaders at the CDC announced their resignations, and the HHS revealed that CDC Director Susan Monarez would no longer be part of the agency, although Monarez is contesting her dismissal.

This follows several weeks of upheaval for the CDC, during which a shooting incident at the agency’s headquarters in Atlanta resulted in the death of a police officer, and approximately 600 employees were subsequently laid off.

At the heart of the issue is mounting tension over claims by staff that HHS leadership is attempting to limit vaccine access and prioritize political goals over public health interests.

Kennedy said Thursday morning on Fox News that he is trying to “fix” an agency that has fallen into a “malaise.”

Here are five things to know about the leadership crisis at the CDC.

Monarez resists ouster

On Wednesday, the HHS stated that Monarez, who had been confirmed as CDC director by the Senate just the month before, was no longer with the agency after she reportedly defied pressure to alter vaccine policy.

Her attorneys quickly issued a statement pushing back.

Prominent Washington, D.C., lawyers Abbe Lowell and Mark Zaid released a statement saying, “When CDC Director Susan Monarez refused to rubber-stamp unscientific, reckless directives and fire dedicated health experts, she prioritized public protection over political agendas, and as a result, she has been targeted.”

“Dr. Monarez has neither resigned nor received notification from the White House that she has been fired, and as a person of integrity and devoted to science, she will not resign.”

The White House confirmed late Wednesday it had “terminated Monarez from her position with the CDC.”

“As her attorney’s statement makes abundantly clear, Susan Monarez is not aligned with the President’s agenda of Making America Healthy Again,” White House spokesperson Kush Desai said in a statement.

The New York Times reported Kennedy told Monarez to resign or be fired amid rising tensions over vaccine policy.  

Monarez told Democrats during her confirmation hearing in June that “vaccines save lives” and that there is no evidence vaccines cause autism spectrum disorder, breaking with Kennedy, a longtime vaccine skeptic who has long speculated on a possible link to autism.

4 senior leaders resign

Hours after Monarez’s departure was reported, four senior leaders at the CDC resigned from the agency. In their resignation letters, these career scientists cited a dissatisfaction with the changes at the CDC and a belief they could not fulfill their public health missions under the current leadership. 

Demetre C. Daskalakis, director of the National Center for Immunization and Respiratory Diseases; Daniel Jernigan, director of the National Center for Emerging and Zoonotic Infectious Diseases; CDC Chief Medical Officer Debra Houry; and Jen Layden, director of the Office of Public Health Data, Surveillance and Technology, submitted their resignations almost simultaneously.

“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,” Daskalakis wrote on social media. 

Houry alleged political interference at the agency. 

“For the good of the nation and the world, the science at CDC should never be censored or subject to political paused or interpretations. Vaccines save lives — this is an indisputable, well-established, scientific fact,” Houry wrote in her resignation email.

Sanders furious, Cassidy vows oversight

The top senators on the Health Committee both called for oversight after the CDC leadership exodus Thursday morning.

Sen. Bill Cassidy (R-La.), chair of the Senate Health, Education, Labor and Pensions (HELP) Committee, reacted to the departures on social media Wednesday, writing, “These high profile departures will require oversight by the HELP Committee.”

Cassidy had struggled with Kennedy’s nomination but eventually voted in favor of his confirmation after receiving assurances that he would have input on the secretary’s actions, including hiring decisions. 

Sen. Bernie Sanders (I-Vt.), ranking member of the HELP Committee, expressed outrage over the situation.

“It’s outrageous that Sec. Kennedy is trying to fire the CDC Director — after only a few weeks on the job — for her commitment to public health & vaccines,” Sanders said in a statement. 

“The Sen. HELP Committee must hold a hearing with Kennedy & the CDC Director as soon as possible. Vaccines save lives. Period,” he added. 

Comes as HHS curbs COVID vaccine access

The departures coincided with recent actions by Kennedy limiting access to COVID-19 vaccines that had previously been available to nearly all people 6 months of age and older. 

Kennedy announced Wednesday that the Food and Drug Administration (FDA) would be rescinding emergency use authorization (EUA) of the COVID-19 vaccines. Under the EUA, children and adults were able to access COVID-19 vaccines regardless of their health status. 

In the absence of the EUAs, access will be determined by what cohorts the FDA has approved the shots for. As of Wednesday, the updated COVID-19 vaccines will only be recommended for “high-risk” groups and seniors.

It remains unclear if and how individuals without underlying conditions can access COVID-19 vaccines, as Kennedy said the vaccines would be available to “all patients” who consult with their doctors.

Kennedy announced earlier this year that the CDC would no longer be recommending COVID-19 vaccines for children without underlying conditions and pregnant women. 

The secretary also fired all 17 members of the CDC’s vaccine advisory committee. He accused members of having conflicts of interest, arguing the move was necessary to restore faith in vaccines. Kennedy then replaced the committee with eight handpicked appointees, some of whom have expressed skepticism over vaccines.  

Deadly shooting at HQ stoked frustration

Earlier this month, a gunman fired 500 rounds into the CDC’s Atlanta headquarters, killing one police officer. The shooter was later identified as a Georgia man who blamed the COVID-19 vaccine for his depression and suicidal thoughts.

Federal workers’ frustration with Kennedy’s leadership erupted after the shooting, with more than 750 HHS employees sending a letter to Congress accusing the secretary of contributing the violent act by sewing mistrust in the vaccine and public health institutions.  

“When a federal health agency is under attack, America’s health is under attack. When the federal workforce is not safe, America is not safe,” the letter reads. “Health and Human Services Secretary Robert F. Kennedy, Jr., is complicit in dismantling America’s public health infrastructure and endangering the nation’s health by repeatedly spreading inaccurate health information.” 

Houry cited the shooting in her resignation, writing, “Recently, the overstating of risks and the rise of misinformation have cost lives, as demonstrated by the highest number of U.S. measles cases in 30 years and the violent attack on our agency.”