Between Knowing and Acting: How Experts Constructed and Communicated Uncertainty During the COVID-19 Pandemic

The COVID-19 pandemic exposed multiple uncertainties shaping scientific reasoning, institutional coordination, and public communication. This article examines how three expert communities in Greece – clinicians, laboratory scientists, and institutional public health officials – constructed and communicated uncertainty. Drawing on 31 semi-structured interviews conducted between January and October 2024, we analyze how uncertainty was perceived, tolerated, and operationalized under urgent decision-making conditions. We introduce the concept of deep science communication to describe iterative, and trust-based exchanges through which experts construct and align knowledge under uncertainty. Our findings show that clinicians relied on heuristics and peer networks to adapt treatment without clear guidelines; laboratory scientists recalibrated protocols without standardized benchmarks; and institutional experts balanced internal pluralism with public coherence to maintain trust. These patterns show that tolerating uncertainty is an active, institutionally mediated process that turns ambiguity into coordinated action. The Greek case illustrates how expert practices, shaped by institutions and crisis pressures, addressed immediate challenges while redefining trust, authority, and knowledge in public life.