Development and duration of human papillomavirus lesions, after initial infection.

Background: To determine the potential value of human papillomavirus (HPV) vaccines, information concerning the incidence and duration of clinically important lesions is needed.
Methods: A total of 603 female university students were followed for a mean duration of 38.8 months. Triannual gynecologic examinations included cervical and vulvovaginal specimen collection for Pap and HPV DNA testing. Women with cytologic evidence of a high-grade squamous intraepithelial lesion (SIL) were referred for colposcopically directed biopsy.
Results: Among women with incident HPV infection, the 36-month cumulative incidence of cervical SILs found by cytologic testing (47.2%; 95% confidence interval [CI], 38.9%-56.4%) was higher than that of vaginal SILs (28.8%; 95% CI, 21.3%-38.2%). The median time to clearance of cervical and vaginal SILs was 5.5 and 4.7 months, respectively. Among women with incident HPV-16 or HPV-18 infection, the 36-month cumulative incidence of cervical intraepithelial neoplasia (CIN) grade 2 was 20.0% (95% CI, 10.8%-35.1%), and that of CIN grade 3 was 6.7% (95% CI, 2.5%-17.0%). The 36-month cumulative incidence of clinically ascertained genital warts among women with incident HPV-6 or HPV-11 infection was 64.2% (95% CI, 50.7%-77.4%).
Conclusions: Intraepithelial lesions are common early events among women with incident HPV infection, and the interval between incident HPV-16 or HPV-18 infection and biopsy-confirmed CIN grade 2-3 appears to be relatively short.