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P832 Effectiveness of the quadrivalent HPV vaccine against HSIL and CIN: a data-linkage study
  1. Robine Donken1,
  2. Arianne Albert2,
  3. C Sarai Racey1,
  4. Laurie Smith3,
  5. Dirk Van Niekerk3,
  6. John Spinelli3,
  7. Heather Pedersen1,
  8. Mel Krajden4,
  9. Monika Naus5,
  10. Cindy Masaro6,
  11. Meena Dawar6,
  12. Manish Sadarangani7,
  13. Gina Ogilvie1
  1. 1University of British Columbia, Vancouver, Canada
  2. 2Women’s Health Research Institute, Vancouver, Canada
  3. 3BC Cancer, Vancouver, Canada
  4. 4BC CDC, Vancouver, Canada
  5. 5University of British Columbia, Faculty of Medicine, Vancouver, Canada
  6. 6Vancouver Coastal Health, Vancouver, Canada
  7. 7BC Children’s Hospital Research Institute, Vaccine Evaluation Center, Vancouver, Canada


Background Although originally approved for three-doses, two doses of the HPV vaccine are now approved for 9–14 year olds in British Columbia (BC), Canada. Post-hoc analyses have shown similar efficacy compared to three-doses even after one-dose. Vaccinated cohorts that include incompletely vaccinated individuals offer the opportunity to evaluate the effectiveness of reduced dosing schedules. We aimed to estimate effectiveness of one-dose of quadrivalent vaccine against high-grade squamous intraepithelial lesion (HSIL) and cervical intraepithelial neoplasia grade 2 or higher (CIN2+).

Methods Data-linkage was performed between the population-based Cervical Cancer Screening Program and immunization registries in BC. Occurrence of HSIL and CIN2+ were compared in a screening cohort of YW born between 1994–2005 who were either (a) unvaccinated; (b) completely vaccinated per-schedule (2-doses 150 days apart or 3-doses) between 9–14 years of age; or (c) vaccinated between 9–14 years of age with one-dose. Relative incidence rates (RR, (95%CI)) were calculated using Poisson regression and adjusted for birth year and age at first screening.

Results Overall, 19,496 women were unvaccinated, 14,130 were completely vaccinated (mean age at vaccination 13.3±1.2), and 471 vaccinated with one dose only (mean age at vaccination 13.4±1.1). We found significant protection among completely vaccinated compared to unvaccinated women. The adjusted RR for HSIL was 0.52 (0.43–0.64) and for CIN2+ 0.42 (0.31–0.57). No significant protection after one dose against HSIL and CIN2+ was observed compared with unvaccinated women, respective adjusted RR 0.69 (0.27–1.41) and 1.21 (0.43–2.86).

Conclusion In this observational study, no evidence of protection of one-dose against HSIL and CIN2+ was observed, while protection was found amongst completely vaccinated. The small sample size and the potential for administrative data biases may have impacted this preliminary analysis. This methodological approach provides a platform for further analyses, with larger numbers, to determine the potential impact of single dose HPV vaccination.

Disclosure No significant relationships.

  • HPV
  • prevention
  • intervention and treatment
  • effectiveness

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