Public health experts warn that a major communication failure could worsen mistrust of vaccines, a problem brought to light by the CDC’s sudden revision of its long-standing autism and vaccines webpage. On November 19, the CDC changed its “Autism and Vaccines” page in a way that shocked many of its own staff. The revision changed the agency’s clear statement that vaccines do not cause autism with new language stating that the claim “vaccines do not cause autism” is not evidence-based.