ICI-VPH: Impact of HPV Immunisation Schedules Against HPV (ICI-VPH)

Centre hospitalier de l'Université de Montréal (CHUM), Ministere de la Sante et des Services Sociaux, Institut National en Santé Publique du Québec

This randomised clinical trial aims to determine whether an immunization schedule comprising two doses of Gardasil administered six months apart is non-inferior to a schedule comprising three doses administered at 0, 6 and 60 months for the prevention of HPV-16 and HPV-18 infections that persist for at least six months, up to ten years after the initial vaccination. The study hypothesis is that the two-dose schedule would offer similar protection as that of a three-dose schedule against persistent HPV-16/18 infections.

The participants who have already received 2 doses of the quadrivalent HPV vaccine (0, 6 months schedule) 5 years before recruitment will not receive an additional dose.

The participants will receive a 3rd dose of quadrivalent HPV vaccine at recruitment visit, which is 5 years after having received two doses of vaccine given 6 months apart in grade 4 (0, 6, 60 months Schedule)

Inclusion Criteria: Having received two doses of Gardasil in 2008-2009, 2009-2010,2010-2011 or 2011-2012 according to 0, 6 months Schedule (between 4 and 12 months) Resident of the regions chosen for the study Exclusion Criteria: Being considered immunosuppressed at time of vaccination (9-10 years-old) or at recruitment visit Being pregnant at recruitment visit