Health experts were shocked to see that thimerosal, a preservative that has largely been phased out of U.S. vaccines, was on the ACIP agenda.

Kennedy, Jr. announced a "clean sweep" of the panel earlier this month. The change comes as infectious diseases like measles and whooping cough make major comebacks this year, and after the secretary said health agencies are facing "a crisis of public trust.

The vast majority of research has failed to show any link between thimerosal and autism or other neurological issues.