This study explores the processes and challenges involved in developing integrated scientific advice during pandemic scenarios through two simulation exercises of an Avian Influenza outbreak in the Netherlands. Using a qualitative, explorative approach, we examine how experts from diverse disciplines collaborated to create recommendations addressing both biomedical and socio-economic aspects of pandemic response. We ask whether and how knowledge from different disciplines on potential consequences of the virus and pandemic measures can be brought together, and how this might be facilitated by an Evidence-to-Decision (EtD) framework. Following Star (1988), Star and Griesemer (1989), and Star and Bowker (1999), we (re)conceptualise the WHO-Integrate-COVID (WICID) framework as a boundary object that supports practices of epistemic fluency for integrated advice. Epistemic fluency is defined as capabilities that allow people to switch between and combine different kinds of knowledge. Through analysis of discussions and ethnographic observations during the simulations, we explore how biomedical and social scientists individually and collaboratively considered the consequences of an Avian Influenza outbreak, and the consequences of potential measures. Our findings suggest that integrated assessment of the scenario may help identify blind spots and clarify the rationale behind recommendations, which could help broadening the quality of policy recommendations to include unintended consequences and communicating measures more effectively. However, differences in understandings of urgency and proportionality could lead to delays in advice. We conclude by discussing the implications for future research on evidence-informed processes of scientific advice, the pro’s and cons of integrated advice, as well as implications for policy and practice.