Article continues below advertisementRobert F. Kennedy Jr.'s run as health secretary has created one of the most problematic rifts between acting CDC officials and a president's appointed staff in the history of the Centers for Disease Control and Prevention organization.RFK Jr.'s stance against vaccines has long been a controversial topic, ultimately leading CDC director Susan Monarez to be fired on Wednesday, August 26, after arguing with the health secretary over her refusal to pull approvals for several COVID-19 vaccines.