In a resignation letter, referring to Kennedy, Marks wrote: “It has become clear that truth and transparency are not desired by the secretary, but rather he wishes subservient confirmation of his misinformation and lies.”

Marks also issued a stark warning, according to media outlets who obtained the letter, saying: “Undermining confidence in well-established vaccines that have met the high standards for quality, safety and effectiveness that have been in place for decades at FDA is irresponsible, detrimental to public health and a clear danger to our nation’s health, safety and security.”

The departure follows reports that Kennedy has turned to a noted vaccine sceptic, David Geier, to lead the HHS in a study of potential links between vaccines and autism. Any links between autism and vaccines have long been debunked.