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Environment

When Controversy Shouldn’t Exist

The science shows no link between vaccines and autism, but the public is still skeptical

by Rachel Sheremeta Pepling
December 15, 2008 | A version of this story appeared in Volume 86, Issue 50

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Credit: iStock
Parents still question the safety of vaccines, but the science can help ease fears.
Credit: iStock
Parents still question the safety of vaccines, but the science can help ease fears.

IN LATE OCTOBER, the “Today Show” aired a segment about Paul A. Offit, a pediatrician who specializes in infectious diseases and vaccines and has written several books on autism. Offit has received several threats because of his very public mission to dispel the belief that vaccines can cause autism.

At the end of the segment, host Matt Lauer talked with NBC’s chief medical editor, Nancy Snyderman. Lauer tried to segue from the segment with the statement, “Controversial subject, Nan...,” but Snyderman cut him short. “It is not controversial, Matt,” she said. Lauer countered that if there were no controversy, then neither she nor Offit would be ambushed by people who still believe there is a vaccine-autism connection. “The science is the science,” replied Snyderman. “It is not controversial.”

Both Lauer and Snyderman are, in a way, right. The science is sound. Overwhelmingly, studies show no causal link between vaccines and autism. So within the scientific community, there is no basis for controversy.

Yet within the general public, particularly within the parental community, the perception of controversy remains. Celebrity moms are taking sides on parenting magazine covers, and parents on online community discussion boards debate whether they should spread out the vaccination schedule for their children—or whether they should vaccinate kids at all.

The hypothesis of a link between the measles-mumps-rubella (MMR) vaccine and autism first arose in a 1998 study published in the Lancet. Since then, 10 of the study’s 13 authors have stated that the data actually were insufficient to suggest a link in the first place.

Emotion, understandably, is intricately tied into the vaccine-autism discussion. But perhaps the science simply hasn’t been made clear.

TO CLARIFY whether other scientific studies supported this hypothesis, the Institute of Medicine (IOM), a nonprofit organization under the National Academies that provides science-based advice on matters of biomedical science, medicine, and health, issued in 2004 a report titled “Immunization Safety Review: Vaccines and Autism.” The committee that put the report together reviewed both published and unpublished epidemiological studies and found that no well-designed studies showed evidence of a causal relationship between autism and the MMR vaccine or vaccines containing the ingredient thimerosal, another autism-causing suspect.

In fact, thimerosal, an ethylmercury-based preservative, was removed from almost all vaccines by 2001 upon the recommendation of the American Academy of Pediatrics and the U.S. Public Health Service. The move was a precautionary measure to minimize children’s exposure to mercury, a known neurotoxin. The flu vaccine still contains very small amounts of the compound, although a thimerosal-free version is available.

Because of the absence of evidence of a link between vaccines and autism, the IOM committee urged researchers to focus on the cause of autism, rather than spend more time and resources on a suspected link that shows little promise of stemming what appears to be an epidemic.

The IOM report also included the following statement: “The committee concludes that because autism can be such a devastating disease, any speculation that links vaccines and autism means that this is a significant issue.” And this is where Lauer’s point is both valid and not.

Yes, the perceived link between vaccines and autism is currently a significant issue in the eyes of the general public, but it should not be considered controversial by anyone. Emotion, understandably, is intricately tied into the vaccine-autism discussion. Parents of affected children are looking for answers, for something to blame. And no parent wants to put a child in harm’s way. But perhaps the science, which hasn’t wavered since the 2004 IOM report, simply hasn’t been made clear.

Retired Senior Correspondent Bette Hileman deftly covered the subject of vaccines and autism during her years at C&EN. We’ve compiled her stories into a publicly accessible informational page on C&EN Online at www.cen-online.org/vaccine/vaccine.html. There, you’ll also find links to other useful tools, such as IOM’s report, an information page by the American Academy of Pediatrics, and an up-to-date scientific studies page compiled by the nonprofit organization Every Child By Two. Use this resource for yourself, or share it with colleagues, friends, and family members who have concerns about vaccinating their children.

Those of us with an understanding of the scientific process need to take the time to explain the difference between causality and coincidence and to share that the scientific case against any vaccine-autism link is sound. We also need to communicate that not vaccinating poses greater risks to both individuals and whole communities. Currently, the science is getting lost, and our online package is one small tool to help fix that.

Views expressed in this Insights are those of the author and not necessarily those of ACS.

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