Multiple Vaccines Safe, Not Linked to Autism

Paul A. Offit, MD


April 12, 2013

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Hello. My name is Paul Offit, and I am talking to you today from the Vaccine Education Center at the Children's Hospital of Philadelphia. I would like to talk about an article that was recently published in the Journal of Pediatrics by Frank DeStefano and coworkers[1] from the Centers for Disease Control and Prevention, looking at the relationship between vaccines and autism.

This issue has gone through a number of iterations. Starting in the late 1990s, there was concern that the measles, mumps, and rubella (MMR) vaccine caused autism. Now, 12 studies have shown clearly that there is no relationship between receiving that vaccine and the development of autism. Then the hypothesis shifted to the notion that thimerosal, an ethyl mercury-containing preservative, which was in a number of vaccines given to infants, could cause autism. In this case, 7 studies showed that there was no relationship between receipt of thimerosal-containing vaccines and the development of autism.

The third hypothesis, the one that DeStefano addresses, is the question of whether too many vaccines given too soon can cause autism. This issue was addressed in a study by Mike Smith and Charles Woods[2] a couple of years ago. They found that there was no relationship between the number of vaccines received in the first year of life and the development of autism.

The advance of the DeStefano paper, and what he and his coworkers found, is that there is no relationship between the number of immunologic components in vaccines that were received by children and the development of autism. This is a more detailed look at vaccines and autism.

In general, however, if you take a step back and look at this question, the notion that the number of immunologic components in vaccines could in some way weaken, overwhelm, or perturb the immune system is fanciful. When we are in the womb, we are in a sterile environment. When we leave the womb and enter the birth canal and the world very quickly, we are colonized with trillions of bacteria, to which we make an immune response. The total number of immunologic components in today's vaccines is approximately 165. When you think about the number of antigens that you encounter (remembering that a single bacterium has 2000-6000 immunologic components) and that you are making grams of immunoglobulin every day, that the dust you inhale isn't sterile, and the food and water that you eat and drink aren't sterile...The notion that vaccines would somehow weaken or overwhelm the immune system is certainly not supported by what we know about immunology and microbiology.

The DeStefano paper is an advance in that it further addresses the question of whether children are receiving too many vaccines too soon, and that this somehow leads to autism. Hopefully, parents will be reassured by this. Clearly we don't know the cause or causes of autism, but we do know that vaccines are not to blame.