Efficacy of the AS04-adjuvanted HPV-16/18 vaccine in young Chinese women with oncogenic HPV infection at baseline: post-hoc analysis of a randomized controlled trial

Human papillomavirus (HPV) vaccines are efficacious against HPV infections and associated lesions in women HPV-naïve at vaccination. However, vaccine efficacy (VE) against oncogenic, high-risk HPV (HR-HPV) types in women infected with any other HR-HPV type at first vaccination (baseline) remains unclear. This post-hoc analysis of a phase II/III study (NCT00779766) evaluated AS04-adjuvanted HPV-16/18 (AS04-HPV-16/18) VE against HR-HPV type infection in 871 Chinese women aged 18-25 years over a 72-month follow-up period. Study participants were DNA-negative at baseline to HR-HPV type(s) considered for VE and DNA-positive to any other HR-HPV type. Initial serostatus was not considered. Baseline DNA prevalence was 14.6% for any HR-HPV type and 10.6% excluding HPV-16/18. In the total vaccinated cohort for efficacy, VE against 6-month and 12-month HPV-16/18 persistent infections (PIs) in women DNA-negative to HPV-16/18 but DNA-positive to any other HR-HPV type at baseline was 100.0% (95% Confidence Interval [CI]: 79.8-100.0) and 100.0% (95%CI: 47.2-100.0), respectively. VE against HPV-16/18 incident infections in women DNA-positive to one vaccine type but DNA-negative to the other one at baseline was 66.8% (95%CI: -18.9-92.5). VE against HPV-31/33/45 incident infections, in women DNA-positive to HPV-16/18 and DNA-negative to the considered HPV type at baseline was 71.0% (95%CI: 27.3-89.8). No HPV-16/18 PIs were observed in vaccinated women with non-vaccine HPV A7/A9 species cervical infection at baseline. These findings indicated that women with existing HR-HPV infection at vaccination might still benefit from the AS04-HPV-16/18 vaccine. However, this potential benefit needs further demonstration in the future.