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Thimerosal and Vaccine Safety. Elizabeth Williams, MD Fellow in Vaccinology and Vaccine Safety Vanderbilt University August 30 th , 2012. Overview. Introduction MMR vaccine Thimerosal Risks and Benefits Known Side Effects of Vaccines Video. My Background.
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Thimerosal and Vaccine Safety Elizabeth Williams, MD Fellow in Vaccinology and Vaccine Safety Vanderbilt University August 30th, 2012
Overview Introduction MMR vaccine Thimerosal Risks and Benefits Known Side Effects of Vaccines Video
My Background • University of Georgia – Environmental Health Science • Medical College of Georgia - MD • University of Virginia - Pediatrics residency • Private practice for 2 years • Current: Vanderbilt for Fellowship in Vaccinology and Vaccine Safety • Specific interests in evaluating vaccine related adverse events and addressing parental concerns about childhood vaccines.
MMR Vaccine and Autism • What is the deal with MMR and autism? • A study published by Dr. Andrew Wakefield in 1998 reported a link between MMR vaccine and autism. • Multiple conflicts of interest, unethical and falsified results. • Dr. Wakefield lost his license to practice medicine in the U.K., moved to the U.S. and is supported by followers who still believe his findings were valid.
MMR Vaccine and Autism • Is there any real risk AT ALL that MMR can cause autism or developmental regression? • Before it was realized that this report was false, several large epidemiologic studies were begun and completed to assess this association. • The results? • No other studies have found any association with prior MMR vaccine and autism. • In 2011, the Institute of Medicine reviewed every study evaluating autism and MMR – No link
Thimerosal • What is Thimerosal? • A mercury-containing preservative that prevents contamination of the vaccine • Why was it used in vaccines? • Vaccines should be sterile and therefore need a preservative to prevent contamination. • Is it dangerous for our kids? • Mercury is a naturally occurring substance in the air, water and soil. • The type of mercury used in thimerosal is ethyl-mercury, which is excreted rapidly from the human body. • Methyl-mercury is the type of mercury that can be toxic in large doses (accumulates in some fish, etc).
Thimerosal:Why did they remove it from vaccines? The FDA Modernization Act of 1997. Infants recommended to receive three different vaccines that contained thimerosal —DTaP, hepatitis B and Hib - could have been exposed to a cumulative dose of mercury as high as 187.5 ug by 6 months of age. This cumulative dose exceeded guidelines recommended by the Environmental Protection Agency (EPA) but was below guidelinesby the Food and Drug Administration (FDA).
Bottom line: Thimerosal is safe • Because of this disconnect and uncertainty regarding maximum safe dose, a decision was made to remove thimerosal from childhood vaccines. • Thimerosal is now only in multi-dose Flu shots. • However, ethyl mercury in thimerosal is safe • Many large, well conducted studies have looked at the risk of autism with thimerosaland found NO RISK.
What are the risks of vaccines? • Different for every vaccine. • Vaccine Information Sheets (VIS) or the CDC.gov • Children’s Hospital of Philadelphia (CHOP) Vaccine Education Center • Just like any medicine, some people and children may have a bad reaction to a vaccine. • There are several side effects that we feel confident could be related to vaccines, and some that we feel confident are not.
What are the benefits? We do know that the risks associated if a child contracts a vaccine preventable illness are much higher than known risks associated with vaccines. Choosing to vaccinate is a choice of risks versus benefits.
Example: MMR • Evidence supports the following potential side effects following MMR vaccine: 1. febrile seizures, 2. transient joint pain in women and children, 3. fever, 4. rash, 5. swelling in the glands of the cheek or the neck, 6. temporary low platelet counts, 7. allergic reaction In severely immunodeficient subjects, MMR can cause inclusion body encephalitis.
Example: MMR • Evidence supports that the following ARE NOT related to the MMR vaccine: • Autism • Type 1 Diabetes