Robert F. Kennedy Jr. has repeated that not enough childhood vaccines have been tested in clinical trials against a placebo.

U.S. Health Secretary Robert F. Kennedy Jr.'s newly reconstituted vaccine advisory panel said during its first meeting on Wednesday that it would study the schedule of childhood and adolescent immunizations and review the use of older vaccines.

The newly formed vaccine advisory committee handpicked by Health and Human Services Secretary Robert F. Kennedy Jr. announced that it would examine the cumulative effect of the childhood vaccine schedule and reevaluate hepatitis B immunization recommendations — a move that could shift long-standing practices of how and when children are immunized in the United States.