Use of real-world data for HPV vaccine trial follow-up in the Nordic region.

Post-marketing studies are commonly performed to follow-up on the safety and effectiveness of a drug or vaccine after approval has been obtained. These post-marketing studies may involve the collection of real-world data from registries and clinical biobanks in order to obtain real-world evidence. As this approach can monitor the effects of pharmaceutical products over decades, it is particularly necessary for the development of safe and effective vaccines. A long-term follow-up (LTFU) study was initiated as an extension of a phase 3 clinical study (V501-015; NCT00092534) to assess the effectiveness, immunogenicity and safety of the quadrivalent human papillomavirus (qHPV) vaccine for up to 14 years after the start of vaccination. The LTFU study included participants from Denmark, Iceland, Norway, and Sweden, and assessed qHPV vaccine effectiveness against cervical pre-cancers and cancers caused by the oncogenic HPV types 16 and 18. In particular, our study utilized Nordic national health registries, in which individual patient records were linked by a unique Personal Identity Number. Here, we describe the overall implementation and methodology of the qHPV vaccine LTFU study conducted in the Nordic region. The LTFU study format we describe here supported a comprehensive follow-up process, with near-complete retrieval of registry data and specimens from local laboratories achieved in a timely manner; therefore, we have demonstrated that such a collection is feasible and can be used to address stringent post-marketing requirements.