The human papillomavirus (HPV) vaccine was introduced in 2006 in the United States and recommended for routine vaccination of all females aged 11-12 years. Most of the vaccine used throughout 2014 was the quadrivalent vaccine (4vHPV), which prevents HPV-6, 11, 16 and 18 infection. The authors were interested in the impact of the vaccine and therefore examined HPV prevalence in the National Health and Nutrition Examination Survey (NHANES). They analysed HPV DNA types detected in self-collected cervicovaginal specimens and the demographic, sexual behaviour and self-reported vaccination data from females aged 14-34 years. The authors found that among 14- to 19-year-olds, 4vHPV-type prevalence decreased from 11.5% in 2003-2006 to 3.3% in 2011-2014, when the ≥1-dose coverage was 55%. Among 20- to 24-year-olds, the prevalence decreased from 18.5% in 2003-2006 to 7.2% in 2011-2014, when the ≥1-dose coverage was 43%. Compared with 2003-2006, 4vHPV prevalence in sexually active 14- to 24-year-olds in 2011-2014 decreased 89% among those vaccinated and 34% among those unvaccinated, giving a vaccine effectiveness of 83%. Therefore within 8 years of vaccine introduction, 4vHPV-type prevalence decreased 71% among 14- to 19-year-olds and 61% among 20- to 24-year-olds with a decrease among unvaccinated females being likely due to herd protection.
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