On May 11–12 in San Juan, Puerto Rico the National Vaccine Program Office (NVPO) sponsored a workshop on aluminum in vaccines. The meeting was attended by a diverse group of vaccinologists, immunologists, experts on metals, pathologists, rheumatologists, and other interested parties.
The objectives of this meeting were to: (1) establish a better understanding of the role and need of aluminum as an adjuvant in vaccines; (2) explore the possibility of adverse events due to the use of aluminum in vaccines; and (3) develop a research agenda to expand existing knowledge of the impact of aluminum on the human body. From the Metal Ions in Biology and Medicine International Symposium held immediately
prior to the aluminum workshop, we learned about “pervasive uncertainty”, a phrase used in this workshop to denote missing data on pharmocokinetics and toxicities of aluminum injected into humans. Even with identification of areas needing further study,
it was apparent that aluminum which has been used as a vaccine adjuvant for more than 70 years, has an established safety record with low incidence
of reported adverse events.
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Dr. Norman Baylor, US Food and DrugAdministration, provided a detailed analysis of aluminum adjuvants, as well as regulatory perspectives. The
three general types of aluminum-containing adjuvants are:
(1) aluminum hydroxide,
(2) aluminum phosphate, and
(3) alum, or potassium aluminum sulfate.
Each of these types of formulations has different isoelectric points, and properties; they are not simply interchangeable. The efficacy of each salt as an adjuvant depends also on the characteristics of the antigens in the vaccine.
FDA regulations limit the aluminum content of an individual dose of a vaccine to 0.85 mg. of elemental aluminum. This is equivalent to 15 mg. of alum per dose.
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Session II was led off by Dr. Stanley Hem, of Purdue University.
He discussed the pharmacology of aluminum salts, and introduced the workshop participants to just how much aluminum we are exposed to, how much is in us, and how it is handled within the body.
An average daily exposure is about 10–15 mg, most of which comes from foods. While
aluminum adjuvants have been used in vaccines for many years,
their disposition following intramuscular (IM) administration has not been studied because the low dose did not cause detectable changes in the normal plasma concentration (5 ug aluminum/l). Now, accelerator mass spectrometry (AMS) can accurately measure very small concentrations (10
−17 g) of aluminum 26 which has no measurable radiation and is considered safe. Preliminary animal experiments have shown that the aluminum adjuvants are dissolved by citrate in the interstitial fluid, leaving the body rapidly. The ability of the body to eliminate aluminum-containing adjuvants may be partly responsible for the excellent safety record of these adjuvants.
http://archive.hhs.gov/nvpo/nvac/documents/Aluminumws.pdf
