I have been a practicing pediatrician for nearly 30 years. During this time, parental concerns regarding childhood vaccinations have gone in waves. There was a time when people were concerned about the diphtheria/tetanus/pertussis (DTP) vaccine because it produced more reactions than the current version. The older vaccine was the old whole-cell vaccine. When it changed to the newer acellular vaccine, things calmed down.
But this was nothing compared with the wave of parental anxiety produced in the late 1990s related to childhood vaccines and concerns of a possible link with autism.
In February 1998, a highly, highly publicized piece was published in The Lancet medical journal by Wakefield, et al1. The authors claimed that the measles/mumps/rubella (MMR) vaccine contributed to the development of autism in a study of 12 children with the condition. That study – later proved false and retracted by most of the authors and the journal itself –has been haunting parents and pediatricians alike ever since.
The Thimerosol Issue
In 1999, the American Academy of Pediatrics and the U.S. Public Health Service recommended that childhood immunizations be manufactured without the preservative thimerosol. Thimerosol contains small levels of mercury.
This recommendation was made entirely separate from the Wakefield theory and paper. At that time, studies on mercury exposure in children raised alarm about all types of mercury that may put children at risk. The recommendation was an effort to eliminate mercury exposure to children from any and all sources that could be identified. Childhood vaccines were one of the sources included.
However, since the Wakefield paper questioning the MMR vaccine and the thimerosol recommendation coincidentally became popularized at nearly the same time, unsubstantiated theories became widely supported that perhaps it was not the MMR vaccine itself (or any vaccine for that matter) but the thimerosol it contained at the time that leads to autism. The setting for a public outcry and significant parental concern was created and we still have to address these falsities today despite years of evidence to the contrary.
Despite the numerous studies showing thimerosol is not a cause of safety concerns, many parents believe that the increasing number of recommended childhood vaccines leads to higher cumulative mercury doses and a possible risk for autism. It can be very helpful to calm these fears by informing parents that almost all childhood vaccines have not contained thimerosol since 20032.
If parents come to the office hesitant to vaccinate their children because of what they have heard or been told about a link with autism, provide the facts in a prepared handout on the topic.
- Educate parents that 10 of the original 13 authors of the Wakefield paper published a retraction letter in 2004.3 In it, these authors stated the link between the MMR vaccine and autism was false and that there is no connection between the two.
- Inform parents that The Lancet retracted the Wakefield article in 2010 from the published record.
- Let them know that none of the childhood vaccines given today contain thimerosol.
To emphasize the falsity of the thimerosol link to autism, consider providing specific citations of the more than 20 papers refuting the link that have been published in peer-reviewed medical journals4. This will give parents access to scientifically accurate information and helps parents to feel empowered in their research.