Vaccine policy analyses can benefit from natural history studies of human papillomavirus in men.

With the licensure of the human papil-lomavirus (HPV) vaccine in the United States and many other countries, an understanding of the natural history of HPV infection is imperative for establishment of appropriate policies and guidelines for its use. Although our knowledge of the natural history of HPV infection in women has increased dramatically over the past decade, the natural history of HPV infection in men is less known. In this issue of the Journal, Partridge et al. present results from a longitudinal study of HPV infection in US men that is reminiscent of their earlier work on a similar cohort of female students from the same university [1]. In light of the imminent (and highly publicized) policy questions surrounding the appropriate vaccine target population, this study is timely in its contribution to the scarce, yet growing, literature on HPV infection in men. As Partridge et al. note, there have been only a few published longitudinal studies of HPV infection in men [2–5], and none of them report the cumulative incidence of HPV infection. Using samples from 3 genital sites (glans, penile shaft, and scro-tum), urine, and under the fingernails, the authors report the prevalence of HPV infection at enrollment and the cumulative incidence of HPV infection among men 18–20 years of age who had multiple clinic visits over 3 years. The 24-month cumulative incidence of HPV infection of any type among Partridge et al.'s male cohort was 62.4%, which is nearly double that among their female counterparts [1]. Compared to the existing literature on HPV infection in men, their findings reinforce previous studies' common themes regarding both the prevalence and the incidence of HPV infection in men in varied settings: the prevalence of any HPV infection (25.8%) was similar both to that reported for male Danish soldiers of a similar age group [4] and to that reported for males visiting a sexually transmitted disease clinic in The Netherlands [2]. HPV-16 was also found to be the most prevalent HPV type at enrollment and was among those with the highest incidence (although Partridge et al.'s study observed that the highest incidence was for HPV-84, followed by HPV-16). In Partridge et al.'s study, comparisons of HPV detection by use of polymerase chain reaction (PCR) technology revealed minimal difference across genital sites but found decreased sensitivity when urine samples were used, as had been observed in earlier studies [6, 7]. Partridge et al. …