Study Suggests HPV Vaccine Could Have Substantial Impact On Rates of Cervical Cancers

Wednesday, September 21, 2016

Eight years after the introduction of the HPV vaccine in a large, Midwestern community, the vaccine appears to be on its way toward having a significant impact on reducing rates of cervical cancers and pre-cancers.

A new Cincinnati Children’s Hospital Medical Center study shows that prevalence of HPV types included in the vaccine decreased more than 90 percent in vaccinated women and more than 30 percent in unvaccinated women in the community. This decrease in unvaccinated women provides evidence of herd protection, which refers to protection among unvaccinated women because others are vaccinated.

“Our study demonstrates high vaccine effectiveness in a community setting, even among sexually experienced young woman who may already have been exposed to HPV,” says Jessica Kahn, MD, a physician in the Division of Adolescent and Transition Medicine at Cincinnati Children’s and lead author of the study. 

“The tremendous decrease in vaccine-type HPV prevalence – from 35 percent to 3 percent in vaccinated women – is even more notable given that the decrease was among sexually active women who may have been infected prior to vaccination and may have received fewer than the recommended three doses, both of which could reduce vaccine effectiveness. The substantial decrease in vaccine-type HPV was likely due to excellent HPV vaccine efficacy and high vaccination rates in this population.”

Kahn studied three groups of sexually experienced women from 2006-2007 (before vaccine introduction), and at three and seven years after introduction. In all, 1,180 women were recruited from three sites in Cincinnati that provide primary care to adolescents and young adults. 

Vaccine rates increased in these 13- to 26-year-old women from baseline to 71.3 percent over the years, while vaccine-type HPV prevalence declined in both vaccinated and unvaccinated women.

“It will be important for us to assess effectiveness over an even longer period of time to determine whether it is sustained, but these results suggest that vaccination programs could have a substantial population-level impact on rates of HPV-related cancers,” says Kahn.

The study is published online in the journal Clinical Infectious Diseases. The study was funded by two grants from the National Institutes of Health, National Institute of Allergy and Infectious Diseases (NAIAD), (R01 AI073713 and R01 AI104709).