A mercury-based preservative once used in many vaccines does not raise the risk of neurological problems in children, concludes a large federal study that researchers say should reassure parents about the safety of shots their children received a decade or more ago. However, the study did not examine autism. A separate study due out in one year will look at this issue.
For more information https://www.cdc.gov/vaccinesafety/Concerns/thimerosal/