Influenza is a serious public health, economic, and national security threat. Every year, circulating seasonal influenza viruses infect tens of millions of people in the United States, leading to hundreds of thousands of hospitalizations and tens of thousands of deaths (Figure 1).1 Widespread influenza infection can significantly compromise national security by diminishing the domestic workforce (including military personnel), weakening critical infrastructure, and impeding logistics networks. The September 2019 Council of Economic Advisors (CEA) Report estimates that seasonal influenza costs the United States approximately $361 billion per year.