A federal judge issued a preliminary stay blocking major elements of Health and Human Services Secretary Robert F. Kennedy Jr.’s overhaul of U.S. childhood vaccine policy, including a January memo that reduced the routine childhood immunization schedule and 13 appointments to the Advisory Committee on Immunization Practices (ACIP). Judge Brian Murphy’s order came in a suit filed by major medical groups including the American Academy of Pediatrics. The court found procedural problems with the reconstituted ACIP appointments and paused the agency’s revised schedule, effectively cancelling an imminent ACIP meeting and freezing policy changes pending further litigation. Medical societies argued the changes risk lowering vaccination rates; plaintiffs said the administration bypassed statutory advisory processes. HHS and CDC officials can appeal, but the ruling immediately stops the new ACIP structure from meeting “as currently constituted,” according to the order. The decision creates regulatory uncertainty for immunization policy and public-health stakeholders who monitor childhood vaccine recommendations. Public-health groups and pediatric clinicians warned of practical ramifications for vaccine programs, noting the stay delays both planned committee votes and any downstream guidance tied to the contested schedule revisions.