Autism and Vaccines

Do vaccines cause autism? For many years a debate has raged on about whether there is a link between autism, the Measles-Mumps-Rubella (MMR) vaccine, and thimerosal, the mercury-derived preservative that was long used to keep vaccines from spoiling. Over the weekend, Pediatrics published a study showing no link between the MMR vaccine, thimerosal, and autism.

Perhaps you’ve not heard of this issue. We hadn’t, until around the time Eli was getting the bulk of his vaccines. Autism rates in developed nations have been rising sharply over the past few decades, and no good cause has been found. In 1998 Dr. Wakefield thought he’d found one: the MMR vaccine. He and 12 co-authors published an article in the Lancet suggesting a possible link between autism, the MMR vaccine, and a supposedly new type of bowel disease. While the paper didn’t outright claim a causal link among the three, Dr. Wakefield did. In a press conference, he called for the combined MMR vaccine to be withdrawn. This was highly publicized in the UK, and led to a drop in MMR vaccinations. Since then 10 of the 12 co-authors have published a retraction, and the London Sunday Times has revealed that Dr. Wakefield had been paid in part by lawyers working on lawsuits against vaccine manufacturers.

However, all of that came to light in 2004, far too late to stop the panic Dr. Wakefield had unleashed. In 2005 Salon and Rolling Stone published an expose by Robert F. Kennedy Jr. claiming that the government covered up the link between thimerosal and autism, and that the link was definite. Medical studies did not back up that claim. The most notable one was a population study of children in Japan, where the combined MMR vaccine was used from 1989 through 1993, after which single vaccines were used. From the article:

The MMR vaccination rate in the city of Yokohama declined significantly in the birth cohorts of years 1988 through 1992, and not a single vaccination was administered in 1993 or thereafter. In contrast, cumulative incidence of [autism spectrum disorders] up to age seven increased significantly in the birth cohorts of years 1988 through 1996 and most notably rose dramatically beginning with the birth cohort of 1993.

And now we have this most recent Canadian population study.

CONCLUSIONS. The prevalence of pervasive developmental disorder in Montreal was high, increasing in recent birth cohorts as found in most countries. Factors accounting for the increase include a broadening of diagnostic concepts and criteria, increased awareness and, therefore, better identification of children with pervasive developmental disorders in communities and epidemiologic surveys, and improved access to services. The findings ruled out an association between pervasive developmental disorder and either high levels of ethylmercury exposure comparable with those experienced in the United States in the 1990s or 1- or 2-dose measles-mumps-rubella vaccinations.

This is an important issue. Vaccines reduce the incident of diseases. For an example of this, take a look at how the pattern of mumps outbreaks in the UK supports this claim. Stopping vaccinations is, simply put, a bad thing. I have sympathy for those searching for autism’s cause. It can’t be easy, especially when you can’t even get good data on how many cases of autism there are. But the vaccine-autism link has gone from tenuous to vapor-thin. It’s time to shift ever-limited research efforts elsewhere.