The Centers for Disease Control and Prevention revised wording on a vaccine-safety webpage to state that a causal link between childhood vaccines and autism cannot be ruled out. The update follows public pressure from Health Secretary Robert F. Kennedy Jr. and has drawn immediate criticism from medical societies and vaccine scientists who say decades of high-quality studies find no link. Public health groups warned the change could reduce vaccine uptake and undermine trust in immunization programs. Federal officials said the agency will investigate potential mechanisms and communicate findings, but critics say the move risks eroding confidence during a critical respiratory-virus season.