[ExI] The science (?) behind swine-flu vaccinations

[Robert Masters]

http://www.theatlantic.com/doc/200911/brownlee-h1n1


This article in The Atlantic raises some remarkably troubling questions about the rationale behind the current crash program to vaccinate people for swine flu.  The authors highlight several issues, but the most interesting to me is a basic problem in statistical methodology:  the weakness of so-called "cohort studies."  

Why do medical authorities believe flu vaccines are effective at all?  The basic reason, according to the authors, is that people who get vaccinated have far lower death rates (about 50 percent lower) than those who don't.  But--as any elementary statistics student learns--correlation is not causation.  There may be "confounding factors":  e.g., people who choose to be vaccinated may be more health-conscious in general, and more likely to take care of themselves (by exercising, not smoking, etc.) than those who don't.  So the difference in death rates may have nothing to do with the vaccinations.

The researchers who do the cohort comparisons try to factor out obvious confounding variables--but, as one vaccine skeptic remarks, "you can adjust for the confounders you know about, not for the ones you don't."  The only way around this problem is to do the kind of study medical scientists refer to as the "gold standard":  a double-blind placebo-controlled experiment.  You give the vaccine to one group of subjects and an inert substance to another group (randomly, with neither the subjects nor those administering the substances knowing which is which), and then observe whether there are any differences in rates of infection (or in death rates) between the two groups.

Amazingly, however, most medical authorities oppose double-blind testing of flu vaccine, on the grounds that it would be "unethical"!  They argue that  giving ANYONE a placebo (a sham vaccine) would be wrong, because that might  increase the person's risk of getting the flu.  I find this completely incomprehensible.  In the first place, all medical experiments are supposed to be done with INFORMED CONSENT; the subject is supposed to know that he or she is taking a risk (and presumably is willing to do so for the sake of helping to advance medical knowledge).  This is the understanding with experimental cancer treatments and such, and it happens every day.  So what is the ethical problem?

Furthermore, suppose a controlled experiment showed that the vaccine was in fact ineffective.  That would mean the billions of dollars being poured into the immunization program are going down a rathole.  Shouldn't that possibility figure into the ethical equation?

In addition to the problem with unknown confounding variables, there are some big questions about the actual data on death rates.  "In 2004, for example, vaccine production fell behind, causing a 40 percent drop in immunization rates. Yet mortality did not rise....  In 1989, only 15 percent of people over age 65 in the U.S. and Canada were vaccinated against flu. Today, more than 65 percent are immunized. Yet death rates among the elderly during flu season have increased rather than decreased...."  And so on.  

The apparently illogical resistance to putting the flu vaccine to a real scientific test, the authors state, is nothing new.  "The annals of medicine are littered with treatments and tests that became medical doctrine on the slimmest of evidence, and were then declared sacrosanct and beyond scientific investigation. In the 1980s and ’90s, for example, cancer specialists were convinced that high-dose chemotherapy followed by a bone-marrow transplant was the best hope for women with advanced breast cancer, and many refused to enroll their patients in randomized clinical trials that were designed to test transplants against the standard—and far less toxic—therapy. The trials, they said, were unethical, because they knew transplants worked. When the studies were concluded, in 1999 and 2000, it turned out that bone-marrow transplants were killing patients."

It will be most interesting to see how (and whether) the medical authorities respond to this eye-opening article.


Rob Masters








      
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