Susan Monarez told a close associate that she had been asked to do things that were illegal or flew in the face of science

US CDC Director Susan Monarez was fired on Wednesday after resisting changes to vaccine policy that were advanced by Health Secretary Robert F. Kennedy Jnr and that she believed contradicted scientific evidence, a close associate said on Thursday.

The revelation and interviews with top officials who resigned in the wake of the director’s firing underscored the growing division over the US approach to public health and the upheaval at the Centres for Disease Control and Prevention, which protects US health and has played a global role in eradicating smallpox, reducing polio, and controlling HIV/Aids.

Fellow CDC employees cheered the three departing officials as they left the Atlanta campus on Thursday in a show of defiance toward Kennedy and his unscientific claims about vaccines.

Richard Besser, former acting director of the CDC, told reporters that he spoke with Monarez on Wednesday.