(279) Post-Marketing Safety Surveillance of Vaccines in Japan for Older Adults: A Feasibility Assessment of Real-World Data Capabilities

Background: In Japan, post-marketing surveillance (PMS) is mandatory for pharmacovigilance, and the Good Post-marketing Study Practice ordinance recognizes the post-marketing database survey as a viable study design for PMS since 2018. Large-scale healthcare databases are needed to monitor rare post-vaccination adverse events. However, vaccination rates differ by vaccine type under Japan's Immunization Law, with voluntary vaccines particularly prone to inconsistent recording, compared to routine ones.

Objectives: To assess the feasibility of conducting a post-marketing database survey for vaccine safety in persons aged 60 years and older in Japan.

Methods: The study used an iterative multi-step approach, including (1) targeted literature review and data source mapping; (2) consultation with local experts in real-world data (RWD); (3) target surveys of local data providers; and (4) ongoing evaluation of relevant publications that used the specific database.

Results: In Japan, claims databases with extensive coverage of older adults are scarce, and vaccination data are not available in claims as preventive measures are managed separately through the National Immunization Program. Routine vaccines for the elderly (e.g., influenza and pneumococcal), are municipally funded, with individual-level vaccination records maintained by municipal governments. This allows for potential linkage between claims and vaccination data, as exemplified by the VENUS-Life cohort study. Conversely, voluntary vaccination data are not systematically collected in administrative healthcare databases. Vaccination entries in electronic medical records (EMR) (e.g., MID-NET and RWD) is at the discretion of healthcare providers and may be entered in structured fields or notes, leading to uncertainties in data quality and volume. Some claims databases (e.g., JMDC and DeSC Healthcare) have mobile health management apps for vaccination data collection, but the utility is limited by few older registrants and varying responses rates.

Conclusions: The study indicates that monitoring vaccine safety shortly after approval in older adults using RWD is likely to face operational challenges in Japan, particularly for voluntary vaccines. Ministry of Health, Labour and Welfare of Japan aims to create a centralized management system for vaccination and adverse event data by 2027. This initiative could improve voluntary vaccination recording and facilitate the linkage with claims data. However, data access for manufacturer-sponsored research studies is yet to be clarified. Meanwhile, we recommend that data providers work with healthcare systems to integrate vaccination data into EMR and systematically collect such information.