Fort Worth, Texas,
11:16 AM

MMR/thimerosal/mercury: What you should know

A pediatrician looks at autism research

Over time, various concerns about vaccines have been brought up. Basically the way it happens is like this … someone comes up with a theory as to why vaccines might be a cause of autism. The scientific community starts to complete studies to determine if it could be a concern. Over and over, the theories have been disproven. Here are three specific examples of this pattern.

Mercury (Thimerosal)

Thimerosal is a preservative that was used in vaccines starting from the 1940s. The preservative contains a small amount of mercury and chronic mercury toxicity has been shown to be related to psychiatric problems and other medical issues. Because of this, it was brought up as a concern around 1999 because the overall number of vaccinations was increasing that perhaps over time the exposure to mercury could be a cause of autism.

Studies started quickly to determine if this could be the case, but in the meantime, the vaccine companies, at the request of the American Academy of Pediatrics (AAP) and the Food and Drug Administration (FDA), began to take Thimerosal out of their vaccines. Thus, by 2001, Thimerosal (and mercury) were removed from vaccines except for one exception (see below). Fortunately, in 2004, further studies released by Institute of Medicine determined that mercury was not a cause of autism.

Currently, the only vaccines that contain mercury that I offer in my clinic are seasonal flu vaccines when they are given in a mutli-dose vial. I try to order as much “preservative free” flu vaccine as I can so that this is not even a concern for my patients. However, because studies have shown that mercury is not a cause of concern, I do not worry that receiving their flu vaccine from a multi-dose vial would harm my patients.

MMR Vaccine

Autism is generally diagnosed around 15-18 months, right after the time when children receive their measles, mumps and rubella (MMR) vaccinations. I believe that is because of this relationship in time that MMR was ever thought to be associated with autism.

The original paper that reportedly found a relationship between MMR and autism by Andrew Wakefield was published in The Lancet. The research has now been completely discredited after multiple other scientists were unable reproduce the results and significant problems with the methods he used for conducting his research. In addition, further information has come out regarding Dr. Wakefield’s conflicts of interest and his motivation for publishing the paper. Over time, ten of the twelve authors involved in the writing of the paper retracted their support of its conclusion.

Finally, after many years, The Lancet published the following statement, “We wish to make it clear that in this paper no causal link was established between (the) vaccine and autism, as the data were insufficient. However the possibility of such a link was raised and consequent events have had major implications for public health. In view of this, we consider now is the appropriate time that we should together formally retract the interpretation placed upon these findings in the paper.”

Despite this overwhelming criticism of his paper, the damage done by Dr. Wakefield and The Lancet still persists today. Parents continue to ask about and remain fearful of MMR and a possible (although incorrect) link to autism. His belief caused parents to fear the use of MMR vaccine and unfortunately, this often extends to all vaccinations.

Too Much, Too Soon”

Are children getting too many shots too soon?

Will receiving all the scheduled shots, so many more than we got as kids, overload their immune systems?

This is a conversation I often have with parents of newborns. And despite the fact that I’m pro-vaccine, I am not afraid to have discussions with parents who have fears and simply want what is best for their child.

Because of that, I follow the evidence closely and love to see new studies that look at different angles of the vaccine discussion.

That’s why I was I excited to see a recent study in the Journal of the American Medical Association (JAMA) that analyzed children with infections not covered by vaccines to determine how many vaccines they had received and if that was a potential reason why they got the infection.

The research looked at around 200 children with diseases and compared them to 750 other children. Those who contracted the diseases had a total vaccine exposure of 240.6 antigens while those in the control (without the disease) group had 242.9.

What's an Antigen?



So, it doesn’t appear that vaccine load on the immune system is a contributing factors towards children contracting other diseases.

This study is another perspective and further evidence that lends support to the idea that vaccines are one of the most successful, safest advancements in the history of medicine.

Get to know Justin Smith, M.D.

Justin Smith, M.D., is a pediatrician in Trophy Club  and the Medical Advisor for Digital Health for Cook Children's in Fort Worth, Texas. He has an active community on both Facebook and Twitter as @TheDocSmitty and writes weekly for Cook Children's He believes that strategic use of social media and technology by pediatricians to connect with families can deepen their relationship and provide a new level of convenience for both of their busy lifestyles. Dr. Smith’s innovative pediatric clinic, a pediatric clinic “designed by you,” open now. Click to learn more. To make an appointment, call 817-347-8100.

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Carol wright
Definition of antigen was excellent! The entire article was super imformative. I am a healthcare provider and people ask my opinion. Now, I have an answer!