The primary care practitioner is confronted with an array of competing claims, theories and data relating to the putative link between certain childhood immunizations and autism.  In order to evaluate the current evidence in an authoritative and objective manner, the Institute of Medicine recently tasked its Immunization Safety Review Committee to examine the hypothesis that vaccines, specifically the measles-mumps-rubella (MMR) vaccine and thimerosal-containing vaccines, are causally associated with autism.  This committee is comprised of scientists with expertise in the issues at hand; however, financial or professional ties to vaccine development or manufacture constituted exclusionary criteria for committee participation.

In its 2004 report, Immunization Safety Review – Vaccines and Autism, the IOM concluded that:

“…the body of epidemiological evidence favors rejection of a causal relationship between the MMR vaccine and autism. The committee also concludes that the body of epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism. The committee further finds that potential biological mechanisms for vaccine-induced autism that have been generated to date are theoretical only.”

The Committee on Infectious Diseases (C.O.I.D.) of the American Academy of Pediatrics and the Centers for Disease Control and Prevention recommend that all children receive a first dose of MMR vaccine after their first birthday.  Deferral to a later age is not associated with enhanced safety or efficacy, and therefore there is no recommendation in favor of this practice, or for separate administration of the components.  Reasons to defer the MMR vaccine include the following:

• People who are moderately or severely ill at the time the shot is scheduled should usually wait until they recover before getting MMR vaccine.
  
• Pregnant women should wait to get MMR vaccine until after they have given birth. Women should not get pregnant for three months after getting MMR vaccine.
  
• Some people should check with their doctor about whether they should get MMR vaccine, including anyone who:
  
  
  • Has HIV/AIDS, or another disease that affects the immune system
    
  • Is being treated with drugs that affect the immune system, such as steroids, for two weeks or longer
    
  • Has any kind of cancer
    
  • Is taking cancer treatment with x-rays or drugs
    
  • Has ever had a low platelet count (a blood disorder).

• People who recently had a transfusion or were given other blood products should ask their doctor when they may get MMR vaccine

  For more information, see the American Academy of Pediatrics, the Childhood Immunization Support Program, or the National Academies Press.