RFK Jr. announced a halt to all U.S. funding for the global Gavi vaccine alliance. One expert calls it a "travesty and a nightmare."

Health and Human Services Secretary Robert F. Kennedy Jr., a prominent vaccine skeptic, on Wednesday announced the U.S. would no longer contribute to Gavi, a global vaccine alliance committed to helping immunize children against deadly diseases, accusing the group of ignoring science and neglecting “the key issue of vaccine safety.”