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.

The preservative thimerosal has been removed from all but a few vaccines, and studies have confirmed no link to neurodevelopmental issues including autism. So public health experts were puzzled when it appeared on the agenda for this week’s meeting of outside vaccine advisers to the US Centers for Disease Control and Prevention.

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.