A federal judge issued a stay that halts major components of Health and Human Services Secretary Robert F. Kennedy Jr.’s changes to U.S. childhood vaccine policy and enjoined votes by the reconstituted Advisory Committee on Immunization Practices (ACIP). The order prevents the CDC’s January memo that reduced recommended childhood vaccines from taking effect while the court considers legal challenges brought by medical societies. The injunction also stayed the appointments of 13 new ACIP members; plaintiffs argued the reconstitution violated advisory‑committee rules. Public health organizations said the decision preserves established evidence‑based immunization processes pending further review.