Effectiveness of the human papillomavirus vaccination program against anogenital warts in Manitoba, Canada

Jan. 4, 2018

The human papillomavirus (HPV) is the most common sexually transmitted infection, which is responsible for virtually all-cervical cancer. Additionally, infection with HPV types 6 and 11 are responsible for 90% of anogenital warts (AGW). Our recent publication examined the effectiveness of the quadrivalent HPV vaccine (qHPV) against the development of AGW in Manitoba. Since AGW incidence peaks months after HPV infection compared to years required to develop cervical cancer the effectiveness of qHPV at reducing the incident risk of AGW provides a good proxy for the ability of vaccination to prevent HPV associated disease.

Vaccination of females at age 18 or younger was associated with a 40% reduction in AGW risk (Hazard Ratio (HR) 0.6; 95%CI 0.4-0.8). Females vaccinated at 19 years, or older were not protected from AGW likely because qHPV is only protective prior to HPV infection. In fact, we found that there was an increased risk of AGW, especially among vaccinated sexually active women (HR 2.8; 95%CI 2.1-3.7). The full study can be found here: http://journals.lww.com/stdjournal/Abstract/publishahead/Early_evidence_of_the_effectiveness_of_the_human.98361.aspx.