The FDA has approved a new, preservative-free formulation for a diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine (Tripedia, Aventis Pasteur, Swiftwater, Pa). The reformulated product contains less than 0.3 µg mercury per dose (as thimerosal), which is less than 5% of the amount of thimerosal in the original version that the FDA approved in 1992.
Although no harmful effects have been reported from thimerosal in vaccines when used at the recommended dosages, federal public health agencies, the American Academy of Pediatrics, and vaccine manufacturers have agreed to reduce or eliminate its use in vaccines to protect children against the potential cumulative health risks of mercury.
Schwetz BA. New Formulation of Tripedia. JAMA. 2001;285(13):1696. doi:10.1001/jama.285.13.1696