Ron Wyden, the incoming Senate finance committee chair, has opened an investigation into evidence that health secretary Robert F Kennedy Jr unlawfully lied to Congress, seeking records from his anti-vaccine group Children's Health Defense about his 2019 Samoa trip and giving it a 4 December deadline. Letters obtained by the Guardian show Kennedy told the Samoan prime minister before the trip that he wanted to study the MMR vaccine, contradicting his confirmation testimony, though Kennedy denies the allegations and the health department has not commented.