Identification and sizing of the current use cases for seasonal influenza vaccines

Introduction: Influenza disease continues to have significant global burden. Despite broader use of seasonal influenza vaccines in high resource settings, our understanding of use cases for seasonal influenza vaccines, their relative size, and their relationship to the barriers to adoption in different populations and settings, is limited. This study is a first attempt to identify the use cases for seasonal influenza vaccines to support the design of global influenza vaccination strategies that are better tailored to different implementation contexts and the development of improved influenza vaccines that are more aligned with the different user needs. Methods: By applying a design-based user-centric approach, we implemented a process, including a desk review, a survey, and interviews, to define the current use cases for seasonal influenza vaccines. Results: Nine use cases have been identified as relevant across all different countries and immunization programme designs and validated by experts. Discussion: The identified use cases of seasonal influenza vaccines can support the optimization of vaccination programmes to increase their public health impact. The use cases identified through this work can help signal to policymakers the most important populations and delivery channels to increase the impact of seasonal influenza vaccination programmes and help estimate programmatic requirements necessary for the supportive policy recommendations. The use cases can also support the design of measures aimed at increasing access in low resource settings and coverage in settings where seasonal vaccines are widely used. The use cases can also help to inform the development, of improved influenza vaccines by highlighting the specific product characteristics relevant to their most impactful uses in different programmatic settings.