Thimerosal and Vaccines
The following has been excerpted from “Responding to Concerns about Thimerosal in Influenza Vaccine” on the AAP Member Center Web site.
The issue of adverse effects from thimerosal in vaccines is a patient educational problem rather than a scientific risk to be communicated to patients. Given this and the fact that more thimerosal-free vaccine product will be available in the upcoming season, many pediatricians may feel no need to discuss thimerosal during risk communication for influenza vaccine. Some pediatricians believe that even a minimal thimerosal reference gives it attention not warranted by the scientific literature. Other pediatricians would argue that because news stories about theoretical risks from thimerosal in vaccines have been so prevalent, this issue is a concern to some parents and may be an immunization barrier. It is true that while no credible scientific evidence linking thimerosal with autism or other childhood neurological disorders exists, class action lawsuits against vaccine administrators have been filed arising from thimerosal in vaccines. As such, pediatricians may find it prudent on a case-by-case basis to discuss the small amount of thimerosal in vaccines, why the risks described in the media lack compelling scientific evidence, and document the discussion.
Experts agree the benefits of the influenza vaccine far outweigh the theoretical risks of thimerosal. The flu vaccines on the market that contain thimerosal yield 12.5 µg per dose. Even with two doses, the thimerosal exposure is minimal and is not considered an issue of substance from a medical/scientific point of view. It is well below the 200 to 230 µg level of acceptable exposure to an infant. Clarifying this issue to parents may require some care to put benefits and risk into perspective.
Some steps to take to manage the risk involved:
- Explain why the influenza vaccine is recommended, the benefits of the vaccine, and the risks of not being immunized.
- For the vaccines that contain thimerosal, inform the parent of its presence as a preservative.
- Tell the parent that the amount of thimerosal is very small and well below acceptable levels. Use the AAP handout "What Parents Should Know About Thimerosal."
- Document that the parent was informed that the vaccine contains small amounts of thimerosal.
If parents need more information, direct them to: Thimerosal in Seasonal Influenza Vaccine” or “What Parents Should Know About Thimerosal.”