Quadrivalent HPV vaccine effectiveness against cervical intraepithelial lesion grade 2 or worse in Norway: A registry-based study of 0,9 million Norwegian women.

In Norway, single cohort vaccination with quadrivalent HPV (qHPV) vaccine targeting 12-year-old girls took place from 2009-2016. In 2020, the oldest vaccinated cohort was 23 years old and had approached the age where risk of being diagnosed with cervical intraepithelial lesion grade 2 or worse (CIN2+) increases rapidly. The aim of this cohort study was to assess direct qHPV vaccine effectiveness (VE) against CIN2+ among Norwegian women aged 16-30 in 2007-2020. By using population-based health registries and individual-level data on vaccination status and potential subsequent CIN2+ incidence, we found 82% qHPV VE among women vaccinated before the age of 17.