Cervical Cancer Vaccine

I have to say, I was pretty stunned when I heard the news that a vaccine had been developed for cervical cancer. Even more amazing, over a 2 year follow-up period, there was 100% efficacy.


That 100% efficacy really applies only to the prevention of 70% of cervical cancer cases.

Don’t get me wrong—I’m really excited by this news. I’m just worried that others, in their very justified excitement, might miss a few crucial caveats, which this article does point out. However, what if you didn’t read the whole article and only read this subhead?

‘100 percent efficacy’ against cancer-causing virus, maker says

The statement isn’t wrong. There was 100% efficacy (or success rate in a clinical trial) of the vaccine against two particular strains of the human papillomavirus (HPV). While nearly all instances of cervical cancer are caused by some form of HPV, the two forms against which this vaccine is apparently effective cause 70% of those cases. That the vaccine works against these two particular strains is actually pretty damn good.

There are a couple of other things to note from the article, which I’ll summarize in bullet points:

  • The study involved 12,000 patients and had a 2-year follow-up, which is pretty compelling.
  • While 2 years is a pretty good length of time, it’s not clear if in the longer term, the vaccine will become less effective, perhaps making booster shots necessary.
  • One woman (out of nearly 6000) did develop precancerous cells, so there is still a slight risk over the long term.
  • The inconvenience of needing 3 shots in 6 months might reduce real world effectiveness.
  • The vaccine is also effective against two strains of the virus that cause 90% of genital warts.

Overall, I think it’s actually a pretty rosy picture.

This post refers to:

Associated Press (via CNN.com). Study: Vaccine blocks cervical cancer. October 6, 2005

Grady, Denise. Vaccine Prevents Most Cervical Cancer. New York Times. October 7, 2005

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