The committee does not regard this study as providing evidence that the investigators have successfully measured antibodies to squalene.

Future Research Directions Regarding Squalene

As squalene continues to be investigated for a number of clinical uses, ongoing toxicity studies will provide the additional information that is needed about its toxicity, both in animals and in humans. It will be important to examine the relevance of animal studies because of species differences in the absorption of squalene and the susceptibility of certain strains of animals to squalene’s effects. In considering future research directions, the committee focused on squalene’s potential use as a vaccine adjuvant. Research questions that remain to be addressed include the following:

  • What types of immune responses does exogenous squalene evoke?

  • Does the immune response differ with the route of administration or entry (i.e., oral, cutaneous, intramuscular)?

  • How does the response vary according to the dose of squalene?

  • Is the presence of antibodies to squalene abnormal, and if so, what is their functional significance?

  • Could antibodies to squalene represent the consequences of, rather than the cause of, a pathological process?


The committee felt it would be helpful to the reader to restate the conclusions from this chapter. The conclusions listed below are identical to those made at the end of the respective sections of this chapter.

Anthrax Vaccine

There is a paucity of published peer-reviewed literature on the safety of the anthrax vaccine. The committee located only one randomized peer-reviewed study of the type of anthrax vaccine used in the United States (Brachman et al., 1962). However, the formulation of the vaccine used in that study differs somewhat from the vaccine given to Gulf War veterans (and currently in use). The Brachman study (and other early experimental studies) found transient local and systemic effects (primarily erythema, edema, induration) of the anthrax vaccine. There was no long-term monitoring for adverse outcomes. The committee did not compare the incidence of transient effects with other vaccines.

Studies of the anthrax vaccine have not used active surveillance to systematically evaluate long-term health outcomes. This situation is unfortunately typi-

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