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.