Monday, January 5, 2009

Will Gardasil Create “Super-Bad” HPV?

Leaving aside the issue of side effects, Gardasil and its buddy Cervarix apparently do a pretty good job of protecting most girls against the two strains of HPV that cause 70 percent of cervical cancer cases—for at least a few years.

But what about the spectre of replacement disease?

We all know about the over-use of antibiotics that has created some scary drug-resistant bacteria. We all know that anti-bacterial soaps etc. may not be such a good thing. But what’s less widely reported is that widespread adoption of a vaccine that targets only selected strains of a pathogen can create “replacement disease” when the strains that haven’t been targeted rush happily in to fill the void.

For instance, when Wyeth was creating its popular anti-pneumococcus vaccine Prevnar in the late 1990s, it aimed to wipe out the seven types of bacteria that are—or were—responsible for about 70-80 percent of pneumococcal illnesses. Including all 91 forms of pneumococci would have been complex, cumbersome and cost-prohibitive.

Oops. Apparently they should have included drug-resistant Serotype 19A, rarely seen at the time. Since 2001, rates of meningitis, pneumonia, and bloodstream infections caused by Serotype 19A have increased by roughly 500 percent in children and by about 400 percent in the elderly, while a drug-resistant form of mastoiditis caused by 19A is also steadily becoming more prevalent.

It wouldn’t be fair to blame the rise of Serotype 19A entirely on Prevnar. Nature, and bacteria, move in mysterious and cyclical ways, and Prevnar may simply have exacerbated the situation.

However, the question remains whether Gardasil may eventually create more opportunities for other strains of HPV to do a cheery end-run around the vaccine and perhaps do even worse damage. Particularly when most HPV infections currently fix themselves.

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