Effectiveness of the Quadrivalent Human Papillomavirus Vaccine Against Cervical Dysplasia in Manitoba, Canada

Abstract

A significant percentage of vaccinated women may not be protected against HSIL and lesser dysplasia especially if they were vaccinated at older age (≥ 18) or had abnormal cytology before vaccination. These findings affirm the importance of vaccination before any significant exposure to HPV occurs and underscore the need for screening programs that cover all sexually active women, even if they were vaccinated.

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

“…Our estimates are also largely consistent with the results from our previous study conducted shortly after the introduction of the qHPV vaccine in Manitoba 21 and with a recent study from another Canadian province. 18 A study carried out in Ontario among girls vaccinated in grade 8 (around 13 years of age) reported a 44% (95% CI 13-64%) reduction in rates of cervical dysplasia, detected using physician claims, compared to rates before the implementation of the program.…”

“…10 Although randomized controlled trials (RCTs) have demonstrated the efficacy of the qHPV vaccine in preventing cervical dysplasia, [11][12][13] vaccine effectiveness (VE) in the general population after the introduction of new vaccines into routine practice can be impacted by ineffective vaccination program design and implementation, poor uptake or adherence to vaccination schedules and contemporaneous changes in risk behaviour. [15][16][17][18][19][20][21] We aimed to estimate the VE of the qHPV vaccine, used in Manitoba's school-based and high-risk public programs, against incident cervical dysplasia and to assess the extent to which VE depended on age at vaccination and number of administered vaccine doses. [15][16][17][18][19][20][21] We aimed to estimate the VE of the qHPV vaccine, used in Manitoba's school-based and high-risk public programs, against incident cervical dysplasia and to assess the extent to which VE depended on age at vaccination and number of administered vaccine doses.…”

Cervical cancer screening of HPV vaccinated populations: Cytology, molecular testing, both or none

“…Compared with non-vaccinated women, those vaccinated had a reduced risk of atypical squamous cells of undetermined significance (ASC-US) or worse by up to 60%, and a reduced risk for cervical intraepithelial neoplasia (CIN) grades 2 and 3 by up to 80%. Similarly, evidence of vaccine effectiveness (impact on HPV prevalence and incidence of genital warts) based on individual vaccination status was confirmed by other population-based studies [25–29]. …”

The Early Benefits of Human Papillomavirus Vaccination on Cervical Dysplasia and Anogenital Warts

“…Our results of vaccine impact are generally consistent with previous research on cervical dysplasia. [17][18][19][20] Although all observational studies have reported more conservative estimates than randomized controlled trials, 7 this is not surprising given that trials estimated treatment effects under ideal conditions. This does, however, highlight the importance of observational studies in determining the real-world effectiveness of this vaccine.…”

“…In addition, low vaccine coverage may jeopardize the expected public health benefits and cost-effectiveness of qHPV vaccine programs. As there are currently few studies on the real-world effects of the qHPV vaccine [17][18][19][20][21] and none on the population-level impact of qHPV vaccine programs on the burden of disease, we undertook a populationbased, retrospective cohort study to assess the impact of the qHPV vaccine and Ontario's qHPV vaccination program on the incidence of cervical dysplasia and AGW among adolescent girls.…”