Thimerosal-containing Vaccines a Risk?
Source: A Joint Statement of the American Academy of Pediatrics (AAP) and the United States Public Health Service (PHS), July 7, 1999.
The aap and phs are recommend-ing that all thimerosal-containing vaccines, including recombinant vaccines such as hepatitis B, diphtheria, pertussis, acellular pertussis, tetanus, and Hib, be eliminated from the market as soon as possible. Vaccine manufacturers must come up with a plan to replace existing vaccines with reduced mercury or mercury-free vaccines, and the FDA plans to expeditiously review revised vaccine product applications.
Thimerosal, which contains mercury, has been commonly used (since the 1930s) as a preservative in many vaccines, where it functions as an antimicrobial, especially in multidose containers. There is, however, a growing concern that the administration of multiple, sequential thimerosal-containing vaccines, especially to low-birth-weight infants, could pose a risk. The agencies are quick to point out that there has been no firm clinical evidence of mercury toxicity in vaccine recipients, and children receiving these vaccines do not need to be tested for mercury exposure.
Until the availability of newer vaccines with a reduced level of mercury (or no mercury), the PHS and AAP are recommending that children continue to receive the usual childhood immunizations per the regular schedule, with the exception of hepatitis B vaccine. Since infants born to hepatitis B surface antigen-negative women do not require this vaccine, this vaccine can be deferred until 2-6 months of age when infants weigh more. The New Mexico State Department of Health has taken this recommendation a step farther and suggests that hepatitis B vaccine can be delayed until at least 1 year of age or until a mercury-free vaccine is available.
Both agencies are urging parents to continue to vaccinate their children, arguing that the known risk of inadequate immunization to potentially life-threatening childhood diseases outweighs any theoretical risk from vaccine administration. Nonetheless, it remains to be seen how this situation will affect the availability of certain vaccines over the next year.
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