A Positive Association found between Autism Prevalence and Childhood Vaccination uptake across the U.S. Population

Abstract

The reason for the rapid rise of autism in the United States that began in the 1990s is a mystery. Although individuals probably have a genetic predisposition to develop autism, researchers suspect that one or more environmental triggers are also needed. One of those triggers might be the battery of vaccinations that young children receive. Using regression analysis and controlling for family income and ethnicity, the relationship between the proportion of children who received the recommended vaccines by age 2 years and the prevalence of autism (AUT) or speech or language impairment (SLI) in each U.S. state from 2001 and 2007 was determined. A positive and statistically significant relationship was found: The higher the proportion of children receiving recommended vaccinations, the higher was the prevalence of AUT or SLI. A 1% increase in vaccination was associated with an additional 680 children having AUT or SLI. Neither parental behavior nor access to care affected the results, since vaccination proportions were not significantly related (statistically) to any other disability or to the number of pediatricians in a U.S. state. The results suggest that although mercury has been removed from many vaccines, other culprits may link vaccines to autism. Further study into the relationship between vaccines and autism is warranted.

Acknowledgments

This study includes data from the U.S. National Centers for Health Statistics (NCHS). Any analyses, interpretations, or conclusions reached are the author's own and not those of the NCHS, which is responsible only for the initial data. The author is grateful to José Garrofe Dorea, Anthony Mawson, Jonathan Rose, Paul Turner, and David Yermack as well as seminar participants at Baruch College and two anonymous reviewers for thoughtful comments. Francis Donnelly provided invaluable assistance in creating the geographic information system graphic. The author has two children with pervasive development disorder, not otherwise specified. She has filed a petition in the U.S. Court of Federal Claims under the National Vaccine Injury Compensation Program for one of her children. The author is on the board of directors and research committee of Sensible Action for Ending Mercury-Induced Neurological Disorders (SafeMinds).