CDC study shows HPV vaccine lowers cervical cancer rates in teen girls

By the Centers for Disease Control and Prevention

 

A new study looking at the prevalence of human papillomavirus (HPV) infections in girls and women before and after the introduction of the HPV vaccine shows a significant reduction in vaccine-type HPV in U.S. teens. The study, published in the June issue of The Journal of Infectious Diseases reveals that since the vaccine was introduced in 2006, vaccine-type HPV prevalence decreased 56 percent among female teenagers 14 to 19 years of age.

About 79 million Americans, most in their late teens and early 20s, are infected with HPV. Each year, about 14 million people become newly infected.

Image courtesy of Flickr user janheuninck. 圖片來自Flickr用戶janheuninck。

Image courtesy of Flickr user janheuninck.

“This report shows that HPV vaccine works well, and the report should be a wake-up call to our nation to protect the next generation by increasing HPV vaccination rates,” said CDC Director Tom Frieden. “Unfortunately only one third of girls aged 13 to 17 have been fully vaccinated with HPV vaccine. Countries such as Rwanda have vaccinated more than 80 percent of their teen girls. Our low vaccination rates represent 50,000 preventable tragedies — 50,000 girls alive today will develop cervical cancer over their lifetime that would have been prevented if we reach 80 percent vaccination rates. For every year we delay in doing so, another 4,400 girls will develop cervical cancer in their lifetimes.”

According to CDC, each year in the United States, about 19,000 cancers caused by HPV occur in women, and cervical cancer is the most common. About 8,000 cancers caused by HPV occur each year in men in the United States, and oropharyngeal (throat) cancers are the most common.

The study by Lauri Markowitz and colleagues at the CDC used the National Health and Nutrition Examination Survey data to compare prevalence — or proportion of girls and women aged 14 to 59 years with certain types of HPV — before the start of the HPV vaccination program (2003-2006) with the prevalence after vaccine introduction (2007-2010). As expected from clinical trials before the vaccine was licensed, the study also showed that the vaccine is highly effective.

“The decline in vaccine type prevalence is higher than expected and could be due to factors such as to herd immunity, high effectiveness with less than a complete three-dose series and/or changes in sexual behavior we could not measure,” Markowitz said. “This decline is encouraging, given the substantial health and economic burden of HPV-associated disease.”

Through these promising results, public health experts and clinicians look forward to more people getting vaccinated for HPV. Routine vaccination at age 11 to 12 for both boys and girls is recommended, but according to recent national immunization surveys, only about half of all girls in the United States — and far fewer boys — received the first dose of HPV vaccine. A series of three shots is recommended over six months. HPV vaccination is also recommended for older teens and young adults who were not vaccinated when younger.

The journal article is available on The Journal of Infectious Diseases website, http://jid.oxfordjournals.org. For additional information on HPV, visit www.cdc.gov/hpv/.

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One Comment

  1. Steve Michaels

    According to Sharlene Bidini, RD, CSO in a contribution to the Oncology Nurses Community, there is more to this study than meets the eye. Here are a few excerpts of her excellent analysis of the CDC study.

    As related by Dr. Joe Mercola:
    “In her article4, Sharlene Bidini, RD, CSO, points out that the study’s conclusion was based on 740 girls, of which only 358 were sexually active, and of those, only 111 had received at least one dose of the HPV vaccine. In essence, the vast majority was unvaccinated, and nearly half were not at risk of HPV since they weren’t sexually active.

    “If the study authors were trying to determine vaccine effectiveness, why did they include the girls who had not received a single HPV shot or did not report having sex?” she writes.

    “Table 1 from the journal article compares 1,363 girls, aged 14-19, in the pre-vaccine era (2003-2006) to all 740 girls in the post-vaccine era (2007-2010) regardless of sexual history or immunization status.”

    In the pre-vaccine era, an estimated 53 percent of sexually active girls between the ages of 14-19 had HPV. Between 2007 and 2010, the overall prevalence of HPV in the same demographic declined by just over 19 percent to an overall prevalence of nearly 43 percent.

    As Bidini points out, this reduction in HPV prevalence can NOT be claimed to be due to the effectiveness of HPV vaccinations. On the contrary, the data clearly shows that it was the unvaccinated girls in this group that had the best outcome!

    “In 2007-2010, the overall prevalence of HPV was 50 percent in the vaccinated girls (14-19 years), but only 38.6 percent in the unvaccinated girls of the same age.

    Therefore, HPV prevalence dropped 27.3 percent in the unvaccinated girls, but only declined by 5.8 percent in the vaccinated group. In four out of five different measures, the unvaccinated girls had a lower incidence of HPV,” she writes.

    Furthermore, in the single instance where unvaccinated girls had a 9.5 percent higher prevalence of HPV, a note stated that the relative standard error was greater than 30 percent, leading Bidini to suspect that “the confidence interval values must have been extremely wide. Therefore, this particular value is subject to too much variance and doesn’t have much value.”

    Another fact hidden among the reported data was that among the 740 girls included in the post-vaccine era (2007-2010), the prevalence of high-risk, non-vaccine types of HPV also significantly declined, from just under 21 percent to just over 16 percent.

    So, across the board, HPV of all types, whether included in the vaccine or not, declined. This points to a reduction in HPV prevalence that has nothing to do with vaccine coverage. Besides, vaccine uptake was very LOW to begin with.

    All in all, one can conclude that there were serious design flaws involved in this study—whether intentional or not—leading the researchers to erroneously conclude that the vaccine effectiveness was “high.” Clearly the effectiveness of the vaccine was anything but high, since the unvaccinated group fared far better across the board.”

    http://articles.mercola.com/sites/articles/archive/2013/07/16/hpv-vaccine-effectiveness.aspx

    Sometimes, a bit of analysis is required to actually see through the headlines which paint a picture that is NOT supported by the data in the study. I am sure the CDC is complicit in misleading the public on this as they are deeply intertwined with the industry they are supposed to be monitoring.

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