Detection and clearance of type-specific and phylogenetically related genital human papillomavirus infections in young women in new heterosexual relationships.

Background: Understanding the natural history of human papillomavirus (HPV) infections is essential to effective cervical cancer prevention planning. We examined these outcomes in-depth among young women. Methods: The HPV Infection and Transmission among Couples through Heterosexual Activity (HITCH) study is a prospective cohort of 501 college-age women who recently initiated a heterosexual relationship. We tested vaginal samples collected at six clinical visits over 24 months for 36 HPV types. Using rates and Kaplan-Meier analysis, we estimated time-to-event statistics with 95% confidence intervals (CIs) for detection of incident infections and liberal clearance of incident and present-at-baseline infections (separately). We conducted analyses at the woman- and HPV-levels, with HPV types grouped by phylogenetic relatedness. Results: By 24 months, we detected incident infections in 40.4%, CI:33.4-48.4 of women. Incident subgenus 1 (43.4, CI:33.6-56.4), 2 (47.1, CI:39.9-55.5) and 3 (46.6, CI:37.7-57.7) infections cleared at similar rates per 1000 infection-months. We observed similar homogeny in HPV-level clearance rates among present-at-baseline infections. Conclusions: Our woman-level analyses of infection detection and clearance agreed with similar studies. However, our HPV-level analyses did not clearly indicate that high oncogenic risk subgenus 2 infections take longer to clear than their low oncogenic risk and commensal subgenera 1 and 3 counterparts.