ABSTRACT: We report on data and debriefing observations in the context of an immersive simulation conducted to (a) train clinicians and (b) test new protocols and kits, developed in table-top exercises without prior clinical experience to fit anticipated clinical encounters in the setting of the rapidly expanding COVID-19 pandemic. We simulated scenarios with particular relevance for anesthesiology, perioperative and critical care, including (1) cardiac arrest, (2) emergency airway management, (3) tele-instruction for remote guidance and supervision, and (4) transporting an intubated patient. Using a grounded theory approach, three authors (MHA, DLR, EHS) developed emergent themes. First alone and then together, we sought consensus in uncovering overarching themes and constructs from the debriefings. We thus performed an informal qualitative thematic analysis based in a critical realist epistemological position - the understanding that our findings, while real, are affected by situational variables and the observer's perspective[1,2]. We compared data from videos and triangulated the data by member checking. All participants and course instructors volunteered to participate in this educational project and contributed as co-authors to this manuscript. During debriefing, we applied crisis resource management concepts including situation awareness, prioritization of tasks, and clear communication practices, conducting the debriefing with emphasis on current TeamStepps 2.0 terminology and concepts. [3,4] In addition, we re-evaluated formerly familiar processes, as shortcomings of protocols, kits, and interdisciplinary cooperation became apparent. The data provide detailed observations on how immersive simulation and debriefing among peers mitigated the unfamiliarity of individual clinicians and the organization at large with the demands of an unprecedented healthcare crisis. We also observed and report on the anxiety caused by resource constraints, risk to clinicians in the face of limited personal equipment, and the overall uncertainty surrounding COVID-19. We began to summarize, interpret, critique, and discuss our data and debriefing observations in a rapid co-publication in the Journal of Clinical Anesthesia. [Healthcare Simulation to Prepare for the COVID-19 Pandemic][5].