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

Kennedy Jr. new panel of vaccine advisers will re-evaluate the recommended schedule for vaccines for children and teenagers, including for measles and hepatitis B, its new chairman said Wednesday.The new slate of advisers met for the first time Wednesday in Atlanta,

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 — moves that could shift long-standing practices of how and when children are immunized in the United States.