The idea that vaccines are a primary cause of autism has been around for some time. The idea took off in the 1990′s when Andrew Wakefield claimed that the MMR was causing autism, including suggesting that not only was MMR causing autism but was responsible for the rise in diagnoses observed. Later, the idea that the increase in thimerosal exposure in the pediatric vaccine schedule of the 1990′s in the US was proposed by some groups as causing the increase in diagnoses. Both ideas have since been shown to be invalid. As the evidence mounted that the idea that thimerosal and/or MMR caused an autism epidemic was false, the idea that the increase in vaccines themselves was causing autism. This idea was popularized by Jenny McCarthy of Generation Rescue in the slogan “too many too soon”.
Objective To evaluate the association between autism and the level of immunologic stimulation received from vaccines administered during the first 2 years of life.
Study design We analyzed data from a case-control study conducted in 3 managed care organizations (MCOs) of 256 children with autism spectrum disorder (ASD) and 752 control children matched on birth year, sex, and MCO. In addition to the broader category of ASD, we also evaluated autistic disorder and ASD with regression. ASD diagnoses were validated through standardized in-person evaluations. Exposure to total antibody-stimulating proteins and polysaccharides from vaccines was determined by summing the antigen content of each vaccine received, as obtained from immunization registries and medical records. Potential confounding factors were ascertained from parent interviews and medical charts. Conditional logistic regression was used to assess associations between ASD outcomes and exposure to antigens in selected time periods.
Results The aOR (95% CI) of ASD associated with each 25-unit increase in total antigen exposure was 0.999 (0.994-1.003) for cumulative exposure to age 3 months, 0.999 (0.997-1.001) for cumulative exposure to age 7 months, and 0.999 (0.998-1.001) for cumulative exposure to age 2 years. Similarly, no increased risk was found for autistic disorder or ASD with regression.
Conclusion In this study of MCO members, increasing exposure to antibody-stimulating proteins and polysaccharides
in vaccines during the first 2 years of life was not related to the risk of developing an ASD.
The study included autism with regression.
Of the 321 potential case children who participated in standardized assessments, 256 (79.8%) met study criteria for ASD. Among these 256 children, 187 (73%) met the stricter criteria for AD and 49 (19%) met the criteria for ASD with regression.
The authors begin the discussion section with:
We found no evidence indicating an association between exposure to antibody-stimulating proteins and polysaccharides contained in vaccines during the first 2 years of life and the risk of acquiring ASD, AD, or ASD with regression. We also detected no associations when exposures were evaluated as cumulative exposure from birth to 3 months, from birth to 7 months, or from birth to 2 years, or as maximum exposure on a single day during those 3 time periods. These results indicate that parental concerns that their children are receiving too many vaccines in the first 2 years of life or too many vaccines at a single doctor visit are not supported in terms of an increased risk of autism.
Are there limitations to this study? Sure. Enough to discount it or disregard it? No. Will some people discount it and disregard it? Yes.
Thimerosal doesn’t increase autism risk. MMR doesn’t increase autism risk. Number of antigens in vaccines doesn’t increase autism risk. There is limited researcher time and money in this world. It is good that we are applying those resources to other areas of autism etiology.