In fiery Senate testimony this week, US Health Secretary Robert Kennedy Jr. once again set his sights on the nation's top public health agency, the Centers for Disease Control and Prevention (CDC).
His appearance came days after he suddenly fired the new CDC director, Susan Monarez, provoking a group of senior staff to resign in protest.
At the hearing, when asked for an explanation, Kennedy claimed he had asked Ms. Monarez if she was a trustworthy person and she had replied no, to some disbelief from his opponents in the room.
He then admitted he had once described the CDC as the most corrupt agency in government, and strongly hinted he's not finished with his plans to shake up the organization.
Kennedy's words have sparked a furious backlash, with many doctors and scientists increasingly concerned that America's public health systems are being dangerously compromised.
It's a conflict that could have a significant impact not just on health policy in the US but across the world. In the past, the CDC has been instrumental in global health, leading the response to crises from famine, to HIV, to Ebola.
Founded in 1946, the CDC tracks emerging infectious diseases like Covid and is also tasked with tackling long-term or chronic conditions such as heart disease and cancer.
It operates more than 200 specialized laboratories and employs 13,000 people, although that number has been cut by around 2,000 since President Donald Trump returned to office.
It does not approve or license vaccines. That responsibility lies with the Food and Drug Administration. But it does produce official recommendations on who should receive which vaccines through a panel of experts - known as the Advisory Committee on Immunization Practices (ACIP) - and monitors their side effects and other safety concerns.
It was Kennedy's record on vaccines that particularly worried many public health experts when he took office in February.
An activist group he ran for eight years, Children's Health Defense, repeatedly questioned the safety and efficacy of vaccination.
He has described the Covid jab as the most deadly in history and has blamed rising rates of autism on vaccines, an idea that has been categorically debunked by large scientific studies over many years.
So feathers were seriously ruffled just weeks into his tenure when it emerged he had hired a noted vaccine critic, David Geier, to look again at the CDC data on that scientifically disproven link.
Then in June, Kennedy suddenly sacked the entire ACIP panel which advises the CDC on vaccine eligibility after accusing all 17 members of being plagued with persistent conflicts of interest. A new committee, handpicked by the administration, now has the power to change, or even drop, critical recommendations to immunize Americans for certain diseases, as well as shape the childhood vaccination program, although the CDC itself still has the final say on whether to accept that advice.
It's that decision which has now been linked to the firing of the agency's new director in late August, only 29 days into the job.
In a newspaper article this week, Ms. Monarez said she was sacked from the CDC after being told, by Kennedy, to pre-approve the recommendations of the ACIP committee which she said had now been filled with people who have expressed antivaccine rhetoric.
In his testimony, Kennedy stood his ground, accusing her of lying about that exchange and describing her dismissal as absolutely necessary. Ms. Monarez's sacking led to a fresh wave of resignations at the agency as senior staff continued to walk out.
Over the last two weeks the CDC has lost its chief medical officer, its director of immunization and its director of emerging diseases, amongst others. Kennedy was also criticized by some CDC staff for what they felt was a lackluster response to a shooting at the agency's Atlanta headquarters in August.
The next flashpoint could come later this month, as the CDC's new vaccine advisory panel is set to meet to discuss Covid vaccines and other shots, including for hepatitis B and the RSV virus. The panel's recommendations will be scrutinized, not just in the US but globally.
As Kennedy reassesses the CDC's past responses and the integrity of its leadership, the world watches closely, with concerns that America’s health system could shift dangerously under his watch.
