Prick Me, Please

by Howard Fienberg
April 8, 2002

Is the anthrax vaccine safe and effective? We need to know. Postal workers, Congressional staff and assorted journalists were all exposed to anthrax-laced mail this fall. Our soldiers are preparing for possible war with a dictator who has no qualms about using biochemical weapons. There is reason to be worried about B. anthracis (anthrax).


And yet, while we have a vaccine against anthrax, many people at risk are afraid to use it. They worry that it does not work and that it might give them horrible illnesses. They seem to fear the consequences of the vaccine almost as much, if not more than, anthrax itself.


The Food and Drug Administration licensed the vaccine in 1970 for civilians, to protect against possible infection by anthrax bacteria. It has been in use for decades, primarily for veterinarians and those who worked with animal hides and wool, as well as the scientists who studied anthrax. The U.S. military started administering the vaccine in the 1990s and has so far inoculated at least 524,000 military personnel.


But simple longevity does not allay scientific concerns. So we must ask two questions: Does the vaccine work? And is it safe? A recent comprehensive report from the Institute of Medicine (IOM) endeavored to answer those questions.


There has been only one randomized, placebo-controlled trial of the anthrax vaccine, conducted back in 1962 among textile workers (it actually tested an earlier but similar formulation). The study provided solid evidence of the vaccines efficacy, at least regarding cutaneous anthrax. Because of the small sample of inhalational cases, the IOM regards the vaccines effectiveness in that regard to be unsettled.


Why only one study? Only a madman would agree to inhaling weapons-grade anthrax spores voluntarily. The normal regimen of FDA controlled testing is simply unethical in such circumstances. Aside from the 1962 study, researchers have had to rely on animal testing. The IOM concluded that available evidence coupled with reasonable assumptions of analogy demonstrated the vaccine to be effective protection against anthrax, including inhalational anthrax.


What about as a post-exposure measure? Some postal and Congressional workers took the vaccine after their presumed exposure to the anthrax bacteria. So far as we know, none of them died, but that does not prove anything. The IOM does not really touch on this question, since there has been no substantive research on it to date.


So the anthrax vaccine does what it is supposed to do. But is it safe?


Continuing troubles at the facilities of BioPort, the Michigan-based company that is currently the vaccines only producer, have driven some of the fears about vaccine safety. These problems appear to be procedural rather than scientific; they probably have not impacted the vaccine. The FDA became more strict over time and BioPort seems to have been slow in adapting. However, the IOM assured that, since the manufacturing procedure is now under strict FDA control, the produced vaccine is more consistent today than ever.


Early on in the rumor cycle, concerns about the vaccines safety revolved around two supposed contaminants, mycoplasma and squalene. Mycoplasma are a distinctive type of bacteria that lack cell walls. The studies reviewed by the IOM demonstrated no presence of mycoplasma in the vaccine stockpile. In addition, when inserted into the vaccine, the bacteria died within 24 hours. It is safe to say that mycoplasma do not pose much of a threat.


Squalene is a biodegradable polymer oil found in human cells in the skin and liver. Small amounts are released into the blood system to stimulate the immune system when the body is injured. Scientists have experimented with synthetic squalene in a similar way, adding it to vaccines to boost their effectiveness. In this form it is called an adjuvant. Researchers discovered a minute presence of squalene (between 1 and 9 parts per billion) in some vaccine stocks, but found no link with any adverse events reported. Scientific bodies normally conclude that more research is needed. That the IOM decided further investigation of contamination is not warranted at this time is downright noteworthy.


But what about potential effects on the unborn? A March 27 article in the Journal of the American Medical Association detailed a cohort study of inoculated reproduction-aged women. It found that the vaccine had no impact on pregnancy, birth rates or adverse birth outcomes.


On the other hand, the anthrax vaccine is associated with a variety of adverse events health effects following vaccination, but not necessarily caused by it. Surveillance data show mostly mild short-term effects (local events, like redness and swelling and systemic events, like aches, fever and malaise). Such effects are associated with most other vaccinations as well.


No credible scientific evidence points to any long-term harm from the vaccine. Individual soldiers (usually not trained in medicine) have fallen prey to the post-hoc fallacy: I got ill some time after I got my anthrax shots, therefore the shots must have caused my illness. A serviceman told a 60 Minutes episode that Its not a matter of what I think. My body told me that the shot was not good for me. Unfortunately, intuition is no substitute for good science. The IOM could find no convincing evidence of later-onset health effects from inoculated personnel.


Principally because of the immediate mildly adverse effects, the IOM recommended seeking a vaccine with fewer installments than the current six-dose regimen.


While no vaccine is 100 percent safe and effective, the fatal effects of anthrax should outweigh any possible shortcomings or ill effects of the anthrax vaccine. And while we cannot say for certain if the vaccine will help in post-exposure cases, like in Congress and post offices, we can say that it cannot hurt too much.

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