This article goes beyond the study of speech acts to investigate the process of securitization during a health crisis. The article introduces the concept of ‘expert-led securitization’ to account for situations when experts dominate the administrative process that translates a securitizing speech act into extraordinary public policy. Expert-led securitization was particularly salient during the 2009 pandemic flu in Denmark and Sweden. Autonomous public health expert agencies led the national securitization processes, and these never included intense political battles or extensive public debates. In turn, the respective processes resulted in different policies: Sweden’s main response to the pandemic was an extraordinary push to vaccinate its whole population, while Denmark’s was a one-off offer of vaccination to about twenty percent of its people. Hence, the 2009 pandemic example illustrates the added value of investigating the administrative dynamics of securitization when seeking to understand differences in extraordinary policies.