Dr. Greene’s Answer:
At much higher doses, mercury is a known cause of irreversible nerve and brain damage, especially before birth and in the first 6 months of life. Mercury was responsible for the first known epidemic of cerebral palsy from a toxin when it was dumped into Minamata Bay in Japan in the 1950′s by a vinyl plastics factory (Textbook of Pediatrics 1996 WB Saunders). Might it also cause mercury toxicity in children who frequently get mercury-containing vaccines? This has long been a concern with the gamma globulin shot used to prevent Hepatitis A in travelers. Where practical, the Hepatitis A vaccine is a safer and more effective alternative that does not contain mercury. Still, getting a shot of gamma globulin is still far better than getting hepatitis.
Mercury has been used as a preservative in the Hepatitis B vaccine given to all newborns around the first day of life and again when they are only 4 weeks old. While there is no data showing that this has caused harm to children in the doses they get from routine immunization, the AAP and the PHS recently called for the elimination of mercury from all vaccines. A thimerasol-free (mercury-free) Hepatitis B vaccine is now available in many hospitals. Because of this, many neonates are beginning to receive Hepatitis B routinely at birth again.
Currently, all routinely recommended vaccines for children and infants in the United States are available in thimerasol-free forms. The influenza vaccine is the only exception; the most widely-used formulation contains a small amount of thimerasol. formulation. Thimerasol-free flu vaccines are available, but the supply is more limited.
Last reviewed: May 13, 2008