Objective: To examine changes in prevalence of vaginal human papillomavirus (HPV) between 2009-2010 and 2013-2014 among both vaccinated and unvaccinated U.S. women.
Methods: We evaluated HPV prevalence among women 18-59 years old using cross-sectional survey data from three different cycles of the National Health and Nutrition Examination Survey. Data were stratified into four age groups (18-26, 27-34, 35-44, and 45-49 years) to examine trends over time among women of different ages in the postvaccine era. Multivariable analyses, which controlled for descriptive variables, were used to examine the prevalence of quadrivalent vaccine-type HPV by vaccination status.
Results: We observed a significant decrease in the prevalence of vaccine-type HPV among women 18-59 years of age from 2009-2010 to 2013-2014. This decline was only significant in those 18-26 years old when the sample was stratified into the four age groups. Among vaccinated 18-26 year olds, HPV prevalence remained low from 2009-2010 (3.9%) to 2013-2014 (2.0%; prevalence ratio 0.51, 95% CI 0.18-1.46). Unvaccinated women 18-26 years old also demonstrated a significant decrease over time from 19.5% in 2009-2010 to 9.7% in 2013-2014 (prevalence ratio 0.44, 95% CI 0.22-0.91). Prevalence did not significantly change among unvaccinated women 26 years old or older.
Conclusions: The decline in HPV infections among unvaccinated 18- to 26-year-old women suggests that young women in the United States are beginning to benefit from herd immunity resulting from the introduction of the HPV vaccine.