This isn't a topic I've paid much attention to, but this article from the technology blog Ars Technica is the first I've seen that reports on a study which shows some initial positive results from the increased use of the HPV Vaccine.
Just 6 years later, HPV vaccine may already provide herd immunity
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The study screened for the presence of HPV in two populations of sexually active teens and young women at two points: before the introduction of the vaccine in 2006, and four years after its introduction (in 2010). The populations were small (only about 400 at each time point), but still large enough to produce statistically significant results. A bigger problem was that the demographics of the two populations were quite different in terms of several factors associated with risk for HPV infection. The authors used an adjustment factor to control for this, but also provided the raw, unadjusted data.
Given that several clinical trials had shown that the vaccine is effective, it's no real surprise that the rate of infection with the four strains targeted by the vaccine (the ones most commonly associated with cervical cancer) went down significantly, dropping by about a third. (Many of the residual infections may result from not taking a complete course of the vaccine or having started it after the onset of sexual activity.) The big surprise is that the rate also dropped in those who hadn't been vaccinated, going from over 30 percent to under 20 percent. Adjusting for risk factors made the drop even more significant.
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Having no real knowledge of the subject matter, I don't have much to add. However, I figured some folks in Kosland would be interested to learn about this study.