LOS ANGELES – 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 kids received a decade or more ago.
However, the study did not examine autism – the developmental disorder that some critics blame on vaccines. A separate study due out in a year will look at that issue, said scientists at the federal Centers for Disease Control and Prevention, who led the latest analysis and published results in today’s New England Journal of Medicine.
They found no clear link between early exposure to the preservative thimerosal and problems with brain function and behavior in children age 7 to 10. The results are in line with past research that found no connection between vaccines and neurological problems or autism.
Thimerosal (pronounced thih-MEHR’-uh-sawl) has not been used in childhood vaccines since 2001, although it is still in some flu shots.
The new findings apply to children immunized before then, or exposed to the preservative through shots their mothers received while pregnant. Thimerosal was put in vaccines to prevent contamination from bacteria.
Some doctors say the CDC study should reassure parents worried about the safety of vaccines.
“It’s good news for families,” said Dr. Michael Goldstein, vice president of the American Academy of Neurology who works in private practice in Salt Lake City. “There’s no evidence that these vaccines have caused injury.”