Significant decline of HPV 6 infection and genital warts despite low HPV vaccination coverage in young women in Germany: a long-term prospective, cohort data analysis

Background: The introduction of human papillomavirus (HPV) vaccination has resulted in a remarkable decline of genital warts in women and men, but in Germany historical rates of vaccination are relatively low. We report long-term surveillance data on changes in HPV 6 and HPV 11 infection and the prevalence of genital warts in young women in the Wol fsburg HP V e pidemiological s tudy (WOLVES). Methods: Women born in 1983/84, 1988/89, and 1993/94 participated in four cohorts between 2009/10 and 2014/15. Quadrivalent vaccination coverage and prevalence of HPV 6/11 infection and genital warts are reported for participants aged 19−22 years and 24−27 years at the time of sample collection. Statistical analyses were done to compare similarly aged participants using 2 x 2 contingency tables (Röhmel-Mansmann unconditional exact test; two-side alpha of 0.05). Results: A total of 2,456 women were recruited. Between 2010 and 2015, there was a statistically significant decrease in the prevalence of HPV 6 infection among women aged 24−27 years (2.1% versus 0.0%; P<0.0001) and women aged 19−22 years (2.0% versus 0.0%; P=0.0056). There was no significant decline in HPV 11 infection. In total, 52 of 2,341 participants were diagnosed with genital warts. There was a statistically significant drop in the risk of developing genital warts in women aged 24−27 years between 2010 and 2015 (4.7% versus 1.7%, respectively; P=0.0018). The overall risk of developing genital warts in women aged 19−27 years decreased from 3.1% in 2010 to 1.2% in 2015 (P=0.0022). Conclusions: An increase in vaccination coverage was associated with a decreased prevalence of genital warts in young women. A protective effect greater than herd immunity alone was seen despite low vaccination rates. Quadrivalent vaccine had a protective effect on genital HPV 6 infection and an almost fully protective effect on the development of genital warts in the youngest population.