It's the late summer, and an unexplained influenza virus is killing international travelers. Researchers quickly identify the virus as a genetically engineered flu-strain. Intelligence agencies find irrefutable evidence that the virus was created in a secret bioweapons laboratory in a middle income country.  It was accidentally released.  By the end 50 million people are killed by this pathogen.  This was the scenario presented to a group of experts at the Munich Security Conference in February who participated in what is known as a "tabletop exercise" to understand how key international players might respond to a situation like this--and identify ways that such a scenario might be prevented from unfolding in the first place.  My guest today, Jaime Yassif, helped to design and implement this table top exercise. She is a senior fellow at NTI for Global Biological policy and programs. And in our conversation we discuss what this fictional scenario reveals about very real gaps in international policies to prevent a catastrophic biological weapons event.