Autism Not Linked to MMR Vaccine

A new study published in The Annals of Internal Medicine offers 3 strong arguments against a causal relation between Measles-Mumps-Rubella (MMR) vaccination and autism. 

These researchers found no difference in the incidence rate of autism between MMR-vaccinated children and the non-vaccinated cohort in a large, multi-year study. 

Additionally, this study reported the MMR vaccine did not increase the risk of developing autism in subgroups of children, such as those children who had autistic siblings or were considered to be at high-risk for autism. 

The timing of this new study is important since measles outbreaks are being reported by various countries, and throughout the USA during 2019.   

Of the 537,303 Danish children in the cohort study, 440,655 (82%) had received the MMR vaccine. These researchers identified 316 children with a diagnosis of autistic disorder and 422 with a diagnosis of other autistic-spectrum disorders. 

After adjustment for potential confounders, the relative risk of autistic disorder in the group of vaccinated children, as compared with the unvaccinated group, was 0.92 (95 percent confidence interval, 0.68 to 1.24), and the relative risk of another autistic-spectrum disorder was 0.83 (95 percent confidence interval, 0.65 to 1.07). 

There was no association found between the age of the child at the time of vaccination, the time since vaccination, or the date of vaccination, and the development of autistic disorder. 

The rate of MMR vaccination in this study was similar to that in the United States (87.6%) in 1995. 

In an accompanying editorial by Saad B. Omer, MBBS, MD, Ph.D., of Emory University's Rollins School of Public Health, and Inci Yildirim, MD, Ph.D., MSc, of Emory School of Medicine, reported a recent meta-analysis involving 5 large cohort studies and 5 case-control studies, there was no relationship between MMR vaccination and autism. 

These physicians said previous studies of an association between autism and MMR vaccination have been case series, ecologic studies, or cross-sectional studies, and the majority have not used optimal data for risk assessment. 

This new research was supported by grants from the Danish National Research Foundation; the National Vaccine Program Office and National Immunization Program, Centers for Disease Control and Prevention; the National Alliance for Autism Research, and the Novo Nordisk Foundation. 

These authors did not disclose industry conflicts. From the Danish Epidemiology Science Center, Department of Epidemiology and Social Medicine, Århus, Denmark (K.M.M., M.V., P.T., J.O.); the Danish Epidemiology Science Center, Department of Epidemiology Research, Statens Serum Institute, Copenhagen, Denmark (A.H., J.W., M.M.); and the National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta (D.S.). 

This study used registry data and not medical records or direct examination of the children by research staff.