a us executive order directed the cdc and the federal vaccine advisory board to align with an hhs assessment calling for fewer childhood vaccines, and in the same days a major obstetric-gynecological society publicly diverged from cdc guidance on vaccines for pregnant women, including covid-19. two distinct actors — the executive branch and a leading medical society — stepped away from established cdc authority within the same window, while us measles cases topped 2000 in five months. simultaneous movement from opposite directions away from a single public-health authority is the structurally unusual part.