1. Center for Health Security, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
2. Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.
3. Department of Bioengineering, Stanford University, Stanford, CA, USA.
4. Center for International Security and Cooperation, Freeman Spogli Institute for International Studies, Stanford University, Stanford, CA, USA.
5. Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
6. Infectious Diseases Section, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA.
7. Center for Communicable Disease Dynamics, Departments of Epidemiology and Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.