The CDC's newly rebuilt Advisory Committee on Immunization Practices (ACIP) took aim Thursday at a mercury-based preservative long targeted by vaccine skeptics, recommending that children, pregnant women, and all other adults use only single-dose seasonal influenza vaccines without thimerosal.

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.