Active vaccine safety monitoring system using health insurance claims data in Japan: The Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study.

Accurate vaccine safety monitoring requires the integration of both passive and active surveillance systems. In Japan, the development of active surveillance systems has been limited, leading to delays in timely vaccine safety assessments. To bridge this gap, Kyushu University initiated the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study in 2021.

The study utilizes health insurance claims data to establish a pilot active surveillance system for vaccine safety in Japan. However, significant challenges remain when comparing the VENUS study to the Vaccine Safety Datalink (VSD) in the United States. The VSD benefits from standardized data collected across 11 managed care organizations, enabling precise immunization tracking, centralized medical chart reviews, and near real-time rapid cycle analysis using secure systems.

In contrast, the VENUS study relies on fragmented municipal data, lacks comprehensive immunization records, and faces logistical barriers such as requiring hospital-specific Institutional Review Board approval for medical chart reviews. While data security in the VENUS study is maintained through anonymization and secure physical transfer methods, it lacks the robust network infrastructure employed by the VSD. Furthermore, VENUS study data primarily represent National Health Insurance and the latter-stage elderly healthcare insurance system, which limits their generalizability to Japan's broader population.

To improve vaccine safety monitoring in Japan, the VENUS study must overcome these challenges by enhancing data accuracy, incorporating real-time analytical capabilities, and broadening its demographic scope. Addressing these issues is essential to ensure reliable vaccine safety assessments and prevent unnecessary interruptions to immunization programs.