The variations in the natural history of high‐risk <scp>human papillomavirus</scp> infections in Chinese healthy women aged 27–45 years compared with 18–26 years: A prospective cohort study

Data investigating the natural history of high-risk human papillomavirus (HR-HPV) infection in mid-adult women compared with young adult women from regions exhibiting a bimodal distribution pattern are scarce. From November 2012 to September 2019, 3681 healthy women aged 18-45 years from the control group of a bivalent HPV vaccine Phase 3 trial in China were followed over 5.5 years. At scheduled visits (Day 0, months 7, 12, 18, 24, 30, 42, 54, and 66), cervical samples were collected for ThinPrep Pap tests and HPV DNA testing, women with abnormal cytology were referred for colposcopy. Data was analyzed using Cox regression model and a competing risk model. Sensitivity analyses were performed among participants attending all scheduled visits. The incidences of HR-HPV persistent infections (over 6 months [6mPIs]) were 35.5 and 29.0 per 1000 person-years (PYs) (hazard ratio [HR] = 1.21, 95% confidence interval [CI]: 1.00, 1.46), and HR-HPV associated CIN grade 2 or greater (CIN2+) were 4.3 and 1.9 per 1000 PYs (HR = 2.31, 95% CI: 1.25, 4.26) in women aged 18-26 and 27-45 years. Competing risk models showed that the cumulative incidence of HR-HPV infections that progressed to CIN2+ was significantly higher in women aged 18-26 than in women aged 27-45 (5.3% vs. 2.9%, Gray's test p = .0291). The cumulative clearance rates of HR-HPV infections in women aged 18-26 and 27-45 were similar (94.7% vs. 95.8%, Gray's test p = .3309) during the study period. In conclusion, although mid-adult women exhibit lower incidences of HR-HPV infection and associated cervical lesions compared to young women, this population continues to face a substantial risk of acquiring causal HPV infections, which may progress to cervical lesion.