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 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.