What About Vaccine Safety?
from Practice Update, Fall 2004
By James K. Todd, MD, Jules Amer Chair in Community Pediatrics, The Children’s Hospital, Professor of Pediatrics, Microbiology and Preventative Medicine/Biometrics, UCHSC
The best way to improve health outcomes for our patients is to prevent bad outcomes. The Centers for Disease Control (CDC) has called immunization one of the greatest public health successes of the 20th century. We all want to forget the terrible Colorado influenza outbreak of 2003, but instead it should serve as a stern warning to heed the American Academy of Pediatrics (AAP), American Academy of Family Physicians (AAFP) and CDC recommendations to vaccinate children six to 24 months of age and their household contacts, as well as children of all ages with chronic diseases. But in spite of Colorado ’s nation-trailing vaccination rates and continued high rates of some vaccine-preventable diseases, there are always those who raise questions about the safety of vaccines. These speculations worry many parents who don’t have the information to discriminate between hypothesis and fact.
Now we have that information. In 2000, the Centers for Disease Control and Prevention and the National Institutes of Health asked the Institute of Medicine (IOM) to establish an independent expert committee to evaluate evidence regarding whether vaccines cause certain health problems, and to report their conclusions and recommendations.
The IOM Immunization Safety Review Committee’s most notable conclusions were:
- neither thimerosal-containing vaccines or MMR vaccine are associated with autism.
- the hypotheses regarding a link between autism and MMR vaccine and thimerosal-containing vaccines lack supporting evidence and are only theoretical.
- future research to find the cause of autism should be directed toward other promising lines of inquiry that are supported by current knowledge and evidence and offer more promise for providing an answer.
The committee’s conclusion that MMR vaccine is not associated with autism is consistent with its previous report on the topic. The 2004 report explains that in 2001 there were no published epidemiological studies examining the potential association between thimerosal-containing vaccines and neurodevelopmental disorders (NDD). Since 2001, several studies have been published which the committee states ‘consistently provided evidence of no association.’
A review of the current data was just published by Children’s Hospital physician Sarah Parker, who, with colleagues from CDC, has analyzed all the available studies on neurological injury and thimerosol (Sarah K. Parker, MD, Benjamin Schwartz, MD, James Todd, MD and Larry K. Pickering, MD, Thimerosal-Containing Vaccines and Autistic Spectrum Disorder (ASD): A Critical Review of Published Original Data PEDIATRICS Vol. 114 No. 3 September 2004, pp. 793-804). Dr. Parker systematically reviewed published articles that report original data pertinent to the potential association between thimerosal-containing vaccines and ASD/NDDs. Twelve publications that met the selection criteria were identified by the literature search: 10 epidemiologic studies and two pharmacokinetic studies of ethylmercury. The design and quality of the studies showed significant variation. Studies do not demonstrate a link between thimerosal-containing vaccines and ASD. Epidemiologic studies that support a link demonstrated significant design flaws that invalidated their conclusions.
The Conclusion
Dr. Parker’s results support the conclusion that we should not allow the paranoia of a few to undermine our duty to serve and protect our patients. Of note, thimerosal has been removed from all routine childhood vaccinations in the U.S. except some formulations of influenza and dT boosters. For those who remain concerned, options for influenza vaccination that contain no or trace amounts of thimerosal are available, such as Flumist and preservative-free versions of Fluzone and Fluviron. The bottom-line is, we should reassure our patients’ parents and do everything we can to prevent another influenza outbreak like the one experienced last year.
