A pivotal study in women aged 16-26 years demonstrated that the nine-valent human papillomavirus (9vHPV) vaccine was efficacious against high-grade cervical dysplasia related to the HPV types covered by the vaccine. To evaluate whether effectiveness remains above 90% for up to 14 years post-vaccination, a long-term follow-up (LTFU) extension of the study was conducted in Denmark, Norway, and Sweden (