Regulatory approaches for platform-based vaccine development in Japan: Insights from PMDA's experience with COVID-19 and RSV vaccines

The concept of a "platform" in vaccine development and regulatory evaluation has emerged as a strategic framework for accelerating responses to infectious disease outbreaks. By leveraging prior knowledge and applying consistent manufacturing and analytical procedures across multiple products-such as mRNA, viral vector and recombinant protein vaccines-platform approaches enable streamlined development and efficient regulatory reviews. This article presents a Japanese regulatory perspective on platform-based vaccine development, drawing on the Pharmaceuticals and Medical Devices Agency (PMDA)'s experience with both emergency and routine evaluations. Through case-based analyses of COVID-19 vaccines reviewed under emergency conditions and the subsequent post-pandemic evaluation of RSV vaccines under standard timelines, we illustrate how prior knowledge and regulatory flexibility supported timely and robust reviews. These insights contribute to the global dialogue on regulatory science and offer practical considerations for future vaccine innovation.