The number of childhood vaccines administered, either in a single day or during the first 2 years of life, has no bearing on autism risk, new research from the Centers for Disease Control and Prevention (CDC) shows.

The case-control study of more than 1000 children showed that there were no significant differences between those who did and those who did not have an autism spectrum disorder (ASD) in total antigens from vaccines received by age 2 years or in the maximum number of antigens received on a single day.

In addition, increasing exposure to antibody-stimulating proteins or polysaccharides from vaccines from the age of 3 months to 2 years was not associated with risk of developing an ASD.