COMMENTARY

HPV Prevalence: Before and After the HPV Vaccine Era

William T. Basco, Jr, MD, MS

Disclosures

April 14, 2016

Prevalence of HPV After Introduction of the Vaccination Program in the United States

Markowitz LE, Liu G, Hariri S, Steinau M, Dunne EF, Unger ER
Pediatrics. 2016;137:1-9

Study Summary

Universal HPV vaccination has been recommended in the United States since 2006 for females and 2011 for males. Vaccine delivery data show that most patients received the quadrivalent HPV (4vHPV) vaccine. Epidemiologic data demonstrate that uptake of the vaccine has been less than ideal, with slightly more than 50% of females receiving one dose, and less than 40% completing the three-dose series.

This study sought to provide a population-based estimate of the prevalence of HPV disease, an important outcome given our push toward universal vaccination. Data from the Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey, which provides nationally representative estimates, were used to compare the prevalence of HPV from 2009-2012 with that in the prevaccine era (2003-2006). 4vHPV disease prevalence and vaccine history were used to estimate vaccine effectiveness.

In each of the two study periods, more than 2000 female survey participants provided self-collected cervicovaginal swabs for HPV DNA testing and other analyses. In the postvaccine era, 51.4% of girls aged 14-19 years and 32.6% of women aged 20-24 years received at least one dose of HPV vaccine.

Results of HPV DNA testing showed that in the prevaccine era, among girls aged 14-19 years, the prevalence of the 4vHPV strains was 11.5%. In the postvaccine era, 4vHPV prevalence was 4.3%. A similar decline in prevalence was seen among women aged 20-24 years, from 18.5% (prevaccine) to 12.1% (postvaccine). For older age groups, there were no statistically significant changes, but many of those women had not been vaccinated. When strains that were not included in 4vHPV were examined, there were no significant declines in prevalence, including for those in the current nine-valent vaccine.

To estimate vaccine effectiveness, the investigators focused on sexually active females, combining age groups from 14 to 24 years. Overall, the prevalence of the 4vHPV strains was much lower among vaccinated women, at 2.1% compared with 16.9% among unvaccinated females, giving an estimate of the vaccine effectiveness of 89% among sexually active females. The prevalence of other HPV strains did not differ between vaccinated and unvaccinated sexually active females.

The investigators concluded that there has been a 64% reduction in the 4vHPV strains among all vaccinated girls aged 14-19 years, as well as a 34% reduction among all vaccinated women aged 20-24 years. Notably and unsurprisingly, these are the two groups with the highest prevalence of receipt of the 4vHPV vaccine.

Viewpoint

It is very important to demonstrate population-based effectiveness of these vaccines. Although there are concerns about self-collected specimens in any large study such as this one, the nationally representative nature of the data and the large number of adolescents involved are strengths of the study.

It would have been nice if the increasing vaccination rates and declining rates of vaccine-specific strains also provided some herd effects, but the investigators note that vaccine acceptance and delivery in the United States are lower than in countries where herd benefits have been demonstrated. This suggests that if we are able to improve vaccination rates, we might experience herd benefits of HPV vaccination in the United States.

Abstract

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