A Review of the Impact and Effectiveness of the Quadrivalent Human Papillomavirus Vaccine: 10 Years of Clinical Experience in Canada.

Publicly funded administration of the quadrivalent HPV (qHPV) vaccine in school-aged girls was implemented for all Canadian provinces and territories between 2007 and 2009. However, the impact of female qHPV vaccination in Canada has yet to be evaluated. This systematic literature review of studies published between September 1, 2006 and September 1, 2016 looked at real-world evidence related to the effects of qHPV vaccination on prevalence of HPV infection and disease in Canada over the past decade. PubMed was searched for studies published between September 1, 2006 and September 1, 2016. Studies were eligible if one or more of the following outcomes were assessed in individuals receiving the qHPV vaccine though public immunization programs: HPV infection, anogenital warts (AGW), HPV-associated lesions of the anogenital tract. A "pre-public vaccination program" or "unvaccinated" reference group was required. Key HPV conference abstracts were also reviewed. We identified seven eligible studies representing five Canadian provinces. Results reported indicated that the prevalence of HPV types 6, 11, 16, and 18 was lower in qHPV-vaccinated than unvaccinated individuals (1.5% vs. 11.0%, respectively), whereas non-vaccine-covered genotypes were comparable across vaccination status. Risk of AGW incidence decreased by up to 45% in vaccinated cohorts; incidence of cervical intraepithelial neoplasia 2 + was significantly reduced by up to 86% in the post-vaccine era. On the basis of these findings, HPV vaccination programs constitute a successful and effective public health initiative.