There is no link between receiving a number of vaccines early in life and autism, researchers said on Friday.
In a study slated to appear in The Journal of Pediatrics
, researchers said there is no association between receiving "too many vaccines too soon" and autism, despite some fears among parents around the number of vaccines given both on a single day and over the first 2 years of life.
As many as one in 50 U.S. school-age children have been diagnosed with autism, up 72 percent since 2007.
Researchers from the Centers for Disease Control and Prevention and Abt Associates analyzed data from children with and without autism spectrum disorder (ASD), according to a statement from the journal.
Researchers examined each child's cumulative exposure to antigens, the substances in vaccines that cause the body's immune system to produce antibodies to fight disease, and the maximum number of antigens each child received in a single day of vaccination, the journal's statement said.
The antigen totals were the same for children with and without ASD, researchers found.
Autism runs a spectrum from a profound inability to communicate and mental retardation to milder symptoms seen in Asperger's Syndrome.
While scientists believe genetics account for 80 to 90 percent of the risk for developing autism, a growing number of studies are beginning to suggest that a father's age at the time of conception may play a role by increasing risks for genetic mistakes in the sperm that could be passed along to offspring.
Worries about a link between vaccines and autism have persisted for years, despite a growing body of scientific evidence disproving such an association.