Evidence of effective delivery of the human papillomavirus (HPV) vaccine through a publicly funded, school-based program: the Ontario Grade 8 HPV Vaccine Cohort Study
Menée en milieu scolaire auprès d'une cohorte de 55 798 adolescentes nées entre 1994 et 1996, cette étude canadienne évalue, du point de vue du taux d'élèves ayant reçu 3 doses de vaccin selon les recommandations, l'efficacité d'un programme de vaccination contre le papillomavirus humain sur les périodes 2007/2008 et 2009/2010
Résumé en anglais
Background : Proper administration of the human papillomavirus (HPV) vaccine (three doses at 0, 2, and 6 months) will likely influence the vaccine's effectiveness and the impact of vaccination programs on health outcomes. Therefore, we assessed HPV vaccine series completion and on-time dosing in Canada's largest publicly funded, school-based HPV vaccination program.
Methods : Using administrative health and immunization databases, we identified a population-based cohort of girls eligible for Ontario's Grade 8 HPV vaccination program in the 2007/08-2009/10 program years who received at least one dose of the vaccine. We determined the number of doses received and calculated the percentage of girls that completed the three-dose series in Grade 8 and Grades 8-9. To assess on-time dosing, the number of days between doses 1-2, 2-3, and 1-3 was calculated and categorized (e.g., too short, on schedule, too long) based on the manufacturer's recommendations. Analyses were also stratified by program year.
Results : We identified a cohort of 55,798 girls who initiated the vaccination series. Series completion was high in the Grade 8 window (81.8%) and increased approximately 6% in Grade 9. Completion was similar across the three program years. 70.8%, 98.5%, and 86.1% of girls were classified as 'on schedule' for dosing intervals 1-2, 2-3, and 1-3, respectively; 70.0% of girls received all three doses in perfect accordance with dosing recommendations. Stratification revealed that on-time dosing was highest in the first two years of the program (85.6% and 80.6%), but dropped to 42.1% in the 2009/10 year when H1N1 vaccination programs were prioritized.
Conclusions : Our study demonstrates that delivery of the HPV vaccine through a free, school-based program is an effective method of ensuring high completion and on-time dosing, but may not be sufficient to guarantee high coverage.
