Vaccine has early, significant effect on HPV

Just 4 years after the licensing of the quadrivalent human papillomavirus (HPV) vaccine, researchers found a substantial decrease in vaccine-type HPV prevalence and evidence of herd immunity (indirect protection of unvaccinated individuals) among minority, low-income young women, a group at increased risk for HPV infection compared with the general population. This discovery could lead to a reduction in cervical intraepithelial neoplasia and, ultimately, cervical cancer in the community.

The first prophylactic HPV vaccine was licensed for use in the United States in 2006. To determine the effect of vaccination on HPV prevalence in a real-world setting, researchers conducted prevaccination and postvaccination HPV surveillance studies in diverse samples of sexually experienced 13- to 26-year-old women.

The 2006-2007 prevaccination study enrolled 368 young women who had not been vaccinated. The 2009-2010 postvaccination study included 409 young women, of whom 242 had received at least 1 HPV vaccine dose before study enrollment. The mean age of both groups was approximately 19 years, and most were black and non-Hispanic. Study participants completed a questionnaire and were tested for cervicovaginal HPV DNA.

Overall HPV prevalence rates in both study populations were extremely high and rose slightly from the prevaccination to postvaccination studies. The prevalence rate for vaccine-type HPV, however, decreased by 18% among all study participants. The decrease was greater for vaccinated participants (from 32% to 10%) but was also substantial for unvaccinated participants (from 30% to 15%), providing evidence of herd protection. Similar changes were found in the prevalence of high-risk vaccine-type HPV. By comparison, the prevalence of nonvaccine-type HPV increased 14% among all participants.

Researchers say that HPV vaccine is not effective in clearing infection or preventing cervical intraepithelial neoplasia in those who are already infected. The finding that HPV prevalence rates remained high in the postvaccination study highlights the importance of vaccinating girls before they reach 13 years.

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