US senators are renewing calls for Health Secretary Robert F. Kennedy Jr. to resign or be removed, with Senator Ron Wyden seeking a Justice Department investigation over alleged false testimony to Congress. Newly published documents appear to contradict Kennedy’s claim during his 2025 confirmation hearings that his 2019 visit to Samoa had nothing to do with vaccines, intensifying scrutiny of his anti-vaccine activism and its public-health implications.

The documents include a 2019 letter in which Kennedy proposed that Children’s Health Defense investigate Samoa’s MMR vaccines, referring repeatedly to vaccination and vaccine safety. Samoa later experienced a measles outbreak that killed 83 people, mostly children under five, after vaccination coverage fell to about 31%; anti-vaccine campaigners had amplified fears following two infant deaths caused by nurses incorrectly preparing vaccine doses with a muscle relaxant, rather than by the vaccine itself.