Association Between Thimerosal-Containing Vaccine and Autism
BRIEF REPORT Association Between Thimerosal-Containing Vaccine and Autism Anders Hviid, MSc Context Mercuric compounds are nephrotoxic and neurotoxic at high doses. Thi- Michael Stellfeld, MD merosal, a preservative used widely in vaccine formulations, contains ethylmercury. Thus it has been suggested that childhood vaccination with thimerosal-containing vac- Jan Wohlfahrt, MSc cine could be causally related to neurodevelopmental disorders such as autism. Mads Melbye, MD, PhD Objective To determine whether vaccination with a thimerosal-containing vaccine is associated with development of autism. IGH DOSES OF MERCURIC COM- Design, Setting, and Participants Population-based cohort study of all children pounds are nephrotoxic and born in Denmark from January 1, 1990, until December 31, 1996 (N=467450) com- neurotoxic.1 Thimerosal, an paring children vaccinated with a thimerosal-containing vaccine with children vacci- organic compound that con- nated with a thimerosal-free formulation of the same vaccine. Htains ethylmercury, has been widely used Main Outcome Measures Rate ratio (RR) for autism and other autistic-spectrum since the 1930s as a preservative in cer- disorders, including trend with dose of ethylmercury. tain vaccines. In the 1990s, an increas- Results During 2986654 person-years, we identified 440 autism cases and 787 cases ing number of different vaccines con- of other autistic-spectrum disorders. The risk of autism and other autistic-spectrum taining thimerosal were introduced in disorders did not differ significantly between children vaccinated with thimerosal- immunization schedules around the containing vaccine and children vaccinated with thimerosal-free vaccine (RR, 0.85 [95% world, and thus the average cumula- confidence interval {CI}, 0.60-1.20] for autism; RR, 1.12 [95% CI, 0.88-1.43] for other tive exposure to thimerosal in infants has autistic-spectrum disorders).
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