Effectiveness of school‐based and high‐risk human papillomavirus vaccination programs against cervical dysplasia in Manitoba, Canada

Abstract

The effectiveness of a vaccination program is influenced by its design and implementation details and by the target population characteristics. Using routinely collected population‐based individual‐level data, we assessed the effectiveness (against cervical dysplasia) of Manitoba's quadrivalent human papillomavirus (qHPV) routine school‐based vaccination program and a short‐lived campaign that targeted women at high‐risk of developing cervical cancer. Females ≥9 years old who received the qHPV vaccine in Manitoba (Canada) between September 1, 2006, and March 31, 2013 (N = 31,442) were matched on age and area of residence to up to three unvaccinated females. Cox proportional hazards models were used to estimate qHPV VE against high‐grade (HSILs) and low‐grade squamous intraepithelial lesions (LSILs) and atypical squamous cells of undetermined significance (ASCUS). Among 14–17‐year‐old participants who had Pap cytology after enrollment, the adjusted qHPV VE estimates were 30% (17–58%) and 36% (21–48%) against the detection of HSILs and LSILs, respectively. There was, however, no evidence of program effectiveness among females vaccinated at ≥18 years of age and among those with a history of abnormal cytology, who were mostly vaccinated as part of the high‐risk program. Estimates of VE for females vaccinated in the school‐based program are consistent with the expected benefits from qHPV vaccination. No similar benefits were detected among women vaccinated at an older age, and those with abnormal cytology, who were targeted by the high‐risk program. Further efforts should be targeted at achieving higher vaccine coverage among preadolescents, prior to the initiation of sexual activity.

Real‐world effectiveness of HPV vaccination against cervical neoplasia among birth cohorts ineligible for routine vaccination

“…This is the first study to assess the impact of HPV vaccination on high-grade cervical lesions in Norway. Our observations of a reduced risk of high-grade cervical lesions among women who got vaccinated with at least one dose of HPV vaccine below age 20 years and no significant protective vaccine effect among women who got vaccinated at age 20 years and older are consistent with findings from postlicensure observational studies in Denmark, 22 Sweden, 23 Canada 24 and the United States. 25 The same pattern is evident for effectiveness against cervical cancer.…”

Human Papillomavirus Type 16 Disables the Increased Natural Killer Cells in Early Lesions of the Cervix

“…More importantly, it is far away from the curing the disease [22]. Another medicinal product used against high-risk HPV types in Canada is a quadrivalent HPV vaccine (Gardasil, Merck) which was recently proved to be 30-50% effective against lesions caused by all HPV types [23]. Over the past decade, many researchers have devoted time and effort into developing a therapeutic vaccine.…”

Human papillomavirus vaccine effectiveness by age at vaccination: A systematic review

“…Twelve of the 21 studies evaluated the effectiveness of a specific HPV-vaccine (bivalent or quadrivalent), one evaluated the effectiveness of receipt of any of the HPV vaccines and the remaining eight studies did not specify the vaccine. The studies were predominantly conducted in North America and Europe – eight studies were conducted in the United States, 26 , 27 , 30 , 32 , 35 , 38 , 40 , 41 four in Sweden 14 , 34 , 39 , 42 and three in Denmark, 13 , 24 , 42 three in Canada, 33 , 36 , 37 two in Scotland 31 , 43 and one in Belgium. Additionally, one study was conducted in New Zealand ( Table 1 ).…”

“… 35 , 38 , 40 The most common outcome studied was cervical abnormalities. 26 , 27 , 31 , 32 , 36 , 37 , 39 , 41 , 42 , 44 Two studies used diagnosis of cervical cancer as the endpoint of interest ( Table 1 ). 13 , 14 …”

“… 26 , 31 , 32 , 36 , 39 , 41 , 42 , 44 The remaining two studies evaluated high-grade abnormal cytology as the primary outcome of interest. 27 , 37 Figure 4 presents vaccine effectiveness against the highest grade cytology or histology outcome reported in the study. Nine of the 10 studies were retrospective cohort studies, utilizing national health registries, regional immunization or screening registries, or insurance claims databases.…”