In Quebec (Canada), the HPV vaccination program targets 9-10 year-old girls who receive 2 doses of the quadrivalent HPV vaccine (Q-HPV) at 0, 6 months, through a school-based program. The main objectives of ICI-VPH are to evaluate whether a 2-dose schedule (0, 6 months) is non-inferior to a 3-dose schedule (0, 6, 60 months) to prevent persistent HPV 16 and 18 infections and to compare HPV6-11-16-18 GMTs between the 2 study groups, 10 years after the first dose. Here, we present the design of the trial, the baseline characteristics of the participants, and the HPV genotypes identified at recruitment.
We recruited teenage girls who had been vaccinated with 2 doses of Q-HPV in fourth grade, 5 years earlier. The participants were randomized to receive a 3rd dose or not. Participants self-collected a vaginal sample for HPV genotyping at baseline and will do so every 6 months for 5 years. Participants also provided health and behaviour data at baseline and will continue to do so every year for 5 years. We collected a blood sample (first 500 participants) at baseline for HPV serology testing, and other samples will be collected after 2.5 years and 5 years. Self-collected vaginal swabs are tested for HPV by a generic HPV PCR assay, and if positive, tested with the Linear Array for the detection of 36 genotypes.
Between 2013 and 2016, we randomized 3364 participants 13-16 years of age, in the province of Quebec, Canada. The 2 study groups were comparable at recruitment: 92.2% were born in Canada, 85.4% identified as French Canadians, 91.0% were non-smokers, 16.0% were sexually active and 21.2% had used hormonal contraception. Among those reporting sexual activity, 80.5% had had intercourse. Genotyping results at recruitment were available for 216 participants who reported having had intercourse. Among them, HPV prevalence was 8.3% (n=18). Single infections (4.2%) were as frequent as multiple infections (4.2%). The most prevalent types were: HPV 51 and HPV 84 (each 2.8%, n=5); HPV 62 (1.9%, n=4); HPV 53, HPV 66, HPV 73, HPV 89 (each 1.4%, n=3); HPV 33, HPV 56 (each 0.9%, n=2); HPV 31, HPV 35, HPV 39, HPV 40, HPV 42, HPV 58, HPV 59, HPV 67 (each 0.5%, n=1). HPV types 6/11/16/18 were not detected.
Vaccine targeted types were not detected in this cohort of 13-16 year-old, 5 years after vaccination with a 2-dose schedule of Q-HPV. To our knowledge, this ongoing study is the first to assess the role of an HPV booster dose for the Q-HPV vaccine within a high-coverage vaccination program.