Prevalence of Human Papillomavirus Genotypes in Unvaccinated 16-20-Year-Old Males in Quebec, Canada.

Background: The province of Quebec (Canada) has had a school-based Human Papillomavirus (HPV) vaccination program with high coverage since 2008, with more than 90% of girls having received at least one quadrivalent vaccine (4vHPV) dose by age 15. In 2018, Quebec was the first jurisdiction to switch to a mixed schedule (nonavalent+bivalent), and as such wanted to evaluate it. However, when devising an evaluation strategy for new vaccine schedules, the presence of herd effect needs to be ascertained.