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Controversy of Immunizations

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Canada has a long-term goal to remove thimerosal from vaccines and is currently researching altnernatives in order to replace thimerosal with an even safer alternative to ensure that multi-dose vials are sterile (Public Health Agency of Canada, 2007).

Thimerosal & Autism

What is Thimerosal?
Thimerosal is a mercury-based preservative used in the manufacturing process of multidose vaccines. Thimerosal is used in certain vaccines in order to: prevent the growth of bacteria and fungi in vaccines and to stabilize the vaccine so that it remains effective over time. It is crucial to the prevention of infections at the injection site. For example, can infection at the IV site could lead to bloodstream infections and abscesses. It is proven that low-dose exposure to thimerosal has been associated with hypersensitivity reactions. Therefore, if you have hypersensitivity to thimerosal or have a history of anaphylactic attacks you should first inform your physican or health care provider before receiving any immunizations.

Which vaccines contain thimerosal?
The influenza vaccine and most hepatitis B vaccines are multi-dose vaccines, which contain thimerosal as a preservative. For immunization of infants against hepatitis B, parents or guardians in some provinces and territories have the choice of a thimerosal-free vaccine. You can check out The NACI updated statement on thimerosal from July 2007 on the Public Health Association of Canada Website for a complete list of different vaccines that contain thimerosal and the amount of thimerosal the vaccines contain.

Vaccines approved for use in Canada may contain the following:

no thimerosal: these are single-dose preparations in which thimerosal has not been used in any part of the manufacturing process.

trace amounts of thimerosal (< 1.0 ľg/dose): if the preservative has been used in the production process but not added to serve a preservative function in the final product.

thimerosal added as a preservative: Such vaccines are typically those supplied in multi-dose vials with thimerosal added in varying concentrations to prevent contamination with other serious infectious agents. The amount of mercury per dose varies from 2 to 50 ľg per 0.5 mL dose.

Why is thimerosal used in the flu vaccine if other vaccines do not contain it?
The flu vaccine is in a multi-dose vial and thimerosal is used in order to maintain sterility of the vaccine. Thimerosal has a stabilizing in order to ensure the vaccine is effective. Most jurisdictions prefer to use the multi-dose format (10 dose vials) and these require a preservative (thimerosal). Thimerosal will continue to be used in multi-dose vaccines until a safe alternative is found.

Is there a link between thimerosal with autism or other neurodevelopmental disorders? Extensive research has been conducted and to date there is no link between vaccines containing thimerosal and autism or other behaviour disorders. International organizations like the World Health Organization (WHO), the U.S. Food and Drug Administration (U.S. FDA) The National Advisory Committee on Immunization (NACI) have reviewed the thimerosal and they all have concluded that neurological effects from thimerosal in vaccines has never been substantiated.

(Public Health Agency of Canada, 2007)