The US Centers for Disease Control and Prevention has told physician groups, public-health professionals and infectious-disease specialists that they will no longer take part in the working groups that prepare evidence for the Advisory Committee on Immunization Practices, the body that shapes national vaccine recommendations, according to an internal email first reported by Bloomberg. The message said the change was needed to ensure discussions are 'free of influence from any special interest groups,' calling the outside organisations biased because of the populations they represent. About 30 professional societies—among them the American Medical Association, the American Academy of Pediatrics and the Infectious Diseases Society of America—have historically supplied unpaid experts who sift through data on efficacy, safety and cost-effectiveness before ACIP votes. In a joint statement, eight of those groups said the decision is 'irresponsible' and 'dangerous to the nation’s health' because it removes long-standing, independent expertise from the review process. The step marks the second major overhaul of ACIP this summer. In June, Health and Human Services Secretary Robert F. Kennedy Jr. dismissed all 17 voting members of the committee and installed seven replacements, several of whom have questioned the value of routine immunisation. The latest move extends the shake-up to the subcommittees that do much of ACIP’s technical work. Ousted advisers and other specialists warn the restructuring could erode public trust in vaccination guidelines. Seventeen former ACIP members used a New England Journal of Medicine editorial to call for an alternative mechanism to vet vaccine policy, while Democrats on the Senate Health Committee have opened an investigation into Kennedy’s actions. Legal challenges to the changes are also pending.