Bivalent Vaccine Effectiveness Against Type-Specific HPV Positivity: Evidence for Cross-Protection Against Oncogenic Types Among Dutch STI Clinic Visitors

Background. Observational postmarketing studies are important to assess vaccine effectiveness (VE). We estimated VE from the bivalent human papillomavirus (HPV) vaccine against HPV positivity of vaccine and nonvaccine types in a high-risk population. Methods. We included all vaccine-eligible women from the PASSYON study, a biennial cross-sectional survey in Dutch sexually transmitted infection clinics. Vaginal swabs were analyzed using a polymerase chain reaction-based assay (SPF10-LiPA(25)) able to detect the 12 high-risk HPV (hrHPV) types 16/18/31/33/35/39/45/51/52/56/58/59. We compared hrHPV positivity between self-reported vaccinated (>= 1 dose) and unvaccinated women, and estimated VE by a logistic mixed model. Results. We included 1087 women of which 53% were hrHPV positive and 60% reported to be vaccinated. The adjusted pooled VE against HPV-16/18 was 89.9% (81.7%-94.4%). Moreover, we calculated significant VE against nonvaccine types HPV-45 (91%), HPV-35 (57%), HPV-31 (50%), and HPV-52 (37%). Among women who were offered vaccination 5/6 years ago, we estimated similar VE against HPV-16/18 (92%) and all hrHPV types (35%) compared to women who were offered vaccination <5 years ago (83% and 33%, respectively). Conclusion. We demonstrated high VE of the bivalent vaccine against HPV-16/18 and cross-protection against HPV45/ 35/31/52. Protection against HPV-16/18 was sustained up to 6 years postvaccination.