Decline in vaccine-type human papillomavirus prevalence in young men from a Midwest metropolitan area of the United States over the six years after vaccine introduction

Abstract

Purpose: The aim of this study was to determine changes in human papillomavirus (HPV) prevalence among young men from a Midwest metropolitan area over the six years after vaccine introduction, including HPV prevalence in men overall, in vaccinated men to examine vaccine impact and in unvaccinated men to examine herd protection. An exploratory aim was to examine associations between number of vaccine doses and HPV prevalence.

Methods: Men aged 14-26 years reporting male-female and/or male-male sexual contact were recruited from a primary care clinic, sexually transmitted disease clinic, and community setting during two waves of data collection: 2013-2014 (N = 400) and 2016-2017 (N = 347). Participants completed a questionnaire and were tested for penile, scrotal and anal HPV. Changes in prevalence of any (≥1 type) and vaccine-type HPV (HPV6, 11, 16, and/or 18) were examined using propensity score weighted logistic regression. Associations between number of doses and HPV infection were determined using chi-square tests and logistic regression.

Results: The proportion of men with a history of ≥1 HPV vaccine doses increased from 23% to 44% (p < 0.001) from waves 1 to 2. After propensity score weighting, infection with ≥1 vaccine-type HPV significantly decreased among all men (29% to 20%; 31% decrease; odds ratio [OR] = 0.62, 95% confidence interval [CI] = 0.44-0.88) and unvaccinated men (32% to 21%; 36% decrease; OR = 0.56, 95%CI = 0.34-0.86); there was a non-significant decrease (21%) among vaccinated men. Associations between number of doses and HPV prevalence were not statistically significant.

Conclusions: Prevalence of vaccine-type HPV decreased among all, vaccinated, and unvaccinated men six years after HPV vaccine recommendation, supporting vaccine impact and herd protection. Decreases in vaccine-type HPV in all men appear to be due to decreases in unvaccinated men, suggesting that the full impact of vaccination has yet to be realized. Continued monitoring and efforts to vaccinate men prior to sexual initiation are warranted.

Keywords: Effectiveness; Herd protection; Human papillomavirus; Male; Prevalence; Vaccine.