RFK Jr.-appointed ACIP panel voted 8-3 to delay routine MMRV childhood vaccine, first change to immunization schedule

On September 18, 2025, the Advisory Committee on Immunization Practices voted 8-3 to delay routine administration of the MMRV combination vaccine — protecting children against measles, mumps, rubella, and varicella — from the standard 12–15 months to age 4. The vote was the first change to the routine childhood immunization schedule under HHS Secretary Robert F. Kennedy Jr., and it came from a panel whose entire prior membership had been replaced: Kennedy had dismissed all 17 sitting independent scientific experts shortly after his confirmation and substituted his own selections. The two-day meeting was held at CDC headquarters in Atlanta, Georgia.

ACIP is the federal advisory body whose vaccine recommendations are adopted by the CDC and followed by pediatricians and public health agencies nationwide. Prior to Kennedy's tenure, its members were drawn from academic medicine, pediatrics, infectious disease, and public health, with conflicts of interest carefully managed. Kennedy's replacement panel drew immediate scrutiny: observers and STAT News described the September 18–19 sessions as "rocky," with complaints from some members that they had been given insufficient time to review proposal wording before votes. A scheduled vote on changing the hepatitis B vaccine recommendation was postponed amid procedural confusion. Independent pediatric and infectious-disease specialists widely characterized the MMRV delay as unsupported by scientific evidence.

No independent scientific review had recommended delaying the MMRV vaccine from its standard administration window. The MMRV shot covers approximately 15% of children who receive a single-dose form. Public health experts warned that moving it to age 4 would leave children unprotected against four diseases during a critical developmental window. The vote illustrated the direct policy consequence of converting an evidence-based scientific body into a politically appointed one.