January 9, 2013
Pediatricians Call for Thimerosal to Remain as
Vaccine Preservative

Elk Grove Village, IL—The preservative thimerosal should be left in vaccines and should not be subject to a ban contained in a draft treaty from the United Nations Environment Program (UNEP), according to the American Academy of Pediatrics, which endorsed the World Health Organization's position on the ban.

In a statement published online in the journal Pediatrics, AAP said it supported the recommendations drafted by the WHO's Strategic Advisory Group of Experts (SAGE) on immunization at an April meeting.

WHO has sought removal of the thimerosal provision from a draft treaty by the United Nations Environment Program (UNEP). Thimerosal is mercury-based, and that treaty seeks to reduce the hazards of environmental mercury.

Because of controversy over the effects of mercury exposure, thimerosal had been removed from most vaccines in the United States and other western nations by 2001, although it still is used in some adult vaccines. It also is still widely employed as a vaccine preservative in other parts of the world.

Subsequent studies have failed to link vaccines containing thimerosal to significant adverse outcomes, resulting in the AAP's revised position from an earlier one in 1999, which had called for the removal of the preservative from all vaccines.

In a commentary accompanying the AAP's recent statement, Walter Orenstein, MD, of Emory University in Atlanta, and colleagues called for keeping thimerosal as an option for vaccine preservation.

"Thimerosal allows the use of multiuse vials, which reduce vaccine cost and the demand on already constrained cold-chain systems,” the commentators write.

The world's vaccine supply could be harmed by a thimerosal ban, which would necessitate single-use vials, could increase manufacturing costs, reduce manufacturing capacity, increase waste, and make transportation and storage more difficult, according to the commentary.

“The resulting cold-chain requirements would be untenable in many areas of the world because of programmatic challenges and increased workload,” they write, adding, “The continued benefits of thimerosal use in vaccine manufacturing clearly outweigh any perceived risks.”

WHO warns in its recommendation that no viable alternatives exist for thimerosal.

“Replacement of thimerosal with an alternative preservative may affect the quality, safety, and efficacy of vaccines; re-registration would be required by the National Regulatory Authority in each jurisdiction where a reformulated product was intended to be used; currently available alternative preservatives interacted in unpredictable ways with existing vaccines, and there are no consensus alternative preservatives for the near- or mid-term,” the WHO statement notes.

U.S. Pharmacist Social Connect