Herd mentality.

The prevalence of vaccine-type HPV (16, 18, 6, and 11) in the oral cavity of men who were never vaccinated dropped by 37% from 2009-10 → 2015-16. Over that same time, participants reported no differences in the number of oral sex partners, and there was no observed decline in the prevalence of non-vaccine-type HPV. | Chaturvedi, JAMA 2019