Background: Quadrivalent human papillomavirus (HPV) vaccine for prevention of HPV-related cancers and anogenital warts was licensed for use in the United States (US) in 2006 for females, and in 2009 for males. US vaccination uptake has increased over time, but in 2014 only 22% of boys and 40% of girls aged 13-17 had completed the 3-dose series. Declines in anogenital warts are an early indication of population effectiveness of HPV vaccination. Prior to 2006, US prevalence of anogenital warts increased or was stable for both genders in all age groups, but a previous study showed decreases during 2007-2010 in girls aged 15-19.
Methods: We estimated anogenital wart prevalence during 2006-2014 using healthcare claims data from 35 million privately insured individuals aged 15-39. Cases were identified using (1) a diagnosis of condyloma acuminata, or (2) a viral wart diagnosis or anogenital wart medication, combined with a benign anogenital lesion diagnosis or procedure specific for anogenital lesions within 30 days. Annual percent change (APC) in prevalence was estimated using trend data to identify the log-linear model with fewest inflection points.
Results: Prevalence for females aged 15-19 decreased during 2008-2014 (APC=-14%, P<0.01); similarly, prevalence for females aged 20-24 decreased during 2009-2014 (APC=-13%, P<0.01). Prevalence also decreased, but less rapidly, during 2009-2014 for females aged 25-29 (APC=-6%, P<0.01). In males, some decrease was observed during 2009-2014 for those aged 15-19 (APC=-5%, P=0.05), with more significant declines during this period for those aged 20-24 (APC=-7%, P<0.01). Prevalence increased or was stable in all other gender/age groups.
Conclusions: Decreases in anogenital warts were observed among both genders aged 15-24, and in women aged 25-29, the groups most likely to be impacted by introduction of HPV vaccine. Decreased prevalence of anogenital warts in young males, despite low vaccination coverage, may be partially due to herd protection from female vaccination.