Quadrivalent HPV Vaccine Effectiveness Against Cervical Intraepithelial Lesion Grade 2 or Worse in Norway: A Registry-Based Study of 0.9 Million Norwegian Women

Abstract

In Norway, single-cohort vaccination with quadrivalent human papillomavirus (qHPV) vaccine targeting 12-year-old girls took place in 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 neoplasia 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 years 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 age 17 years.