To determine if the human papillomavirus (HPV) vaccination offers cross-protection against nonvaccine HPV types and whether introduction of the vaccination has offered herd immunity to unvaccinated women.METHODS:
We collected and analyzed HPV prevalence data for females aged 18–29 from the prevaccine era (2007–2008) and postvaccine era (2009–2012) using the National Health and Nutrition Examination Surveys (NHANES); 1628 female respondents aged 18–29, representing 21,135,134 females in the United States non-institutionalized civilian population, provided vaginal swabs across three consecutive NHANES survey cycles.RESULTS:
Among females aged 18–29, the prevalence of high risk HPV among women who received at least one dose of the HPV vaccine decreased from 67% (95% confidence interval [CI] 50.7–81.4) in 2007–2008 to 41.5% (95% CI, 30.5–53.1) in 2011–2012; among the women vaccinated for HPV in the postvaccine era, the prevalence of HPV-16 and -18 was 6.4% versus 93.6% for all other high risk HPV types. There was no difference in prevalence in high risk HPV for women who did not receive the vaccine; 49.5% (95% CI, 42.5–56.6) in 2007–2008 versus 50.8% (95% CI, 43.0–58.7) in 2011–2012.CONCLUSION/IMPLICATIONS:
The prevalence of high risk HPV significantly decreased among females aged 18–29 years who received the HPV vaccine, but there appeared to be no cross-protection against nonvaccine HPV types. These findings may offer support for usage of the investigational 9-valent HPV vaccine. There also was no evidence to suggest protection against HPV infection for unvaccinated women.