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Vaccine Safety > Issues of Interest > Autism
California Data on Theory of Autism and MMR Immunization
Time Trends in Autism and in MMR Immunization Coverage in California

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Where to find the 1999 California Report
A 1999 report from the California Department of Developmental Services showed an increase in cases of children with autism. A reason for the increase has not been identified. To view or print the actual report, go to
PDF file

Follow-up analysis and complete study
A follow-up analysis of the data published in 2001 showed that there is no association between autism rates in California and the proportions of young children in this state who have received Measles Mumps Rubella (MMR) vaccine.

There are no recommended childhood vaccines or any other vaccines that are known to cause autism in children.

The complete study by authors Dales L, Hammer SJ, Smith, NJ. Entitled 2001 Time Trends in Autism and in MMR Immunization Coverage in California, published in JAMA 285, 1183-1185.


Facts of the study

  • The study looked at the percent of children born in 1980-1994 and enrolled in California kindergartens who received the MMR vaccine, by age when the vaccine was received, and the number of autism cases enrolled in the California Department of Developmental Services regional service center system.
  • The number of autism cases in California increased greatly, over 373%, compared to only a small 14% increase in MMR vaccine coverage in children for the same time period.
  • If there were a relationship between MMR vaccination and autism, one would expect the shape of the MMR immunization level curve to be very similar to the shape of the autism case number curve. This is not the case, thus the analysis in this study does not support any link between MMR vaccination and autism.


Supporting Information
Information about MMR vaccine

  • Printable version of "what you need to know". Answers the questions: 
    PDF file
    • Why you should get vaccinated

    • Who should get MMR vaccine and when

    • Why some people should not get MMR or should wait

    • What the risks are of the MMR vaccine

    • What if is there is a reaction, etc.

  • Printable version of MMWR report. Summary: Vaccine use and strategies for elimination of Measles, Mumps, and Rubella congenital rubella syndrome and control of mumps. 
    MMWR 1998;47 (No. RR-8).
    PDF file

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This page last modified on March 8, 2001


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