1. Department of Medicine, University of Washington, Seattle, WA 98195, USA.
2. Vaccine and Infectious Diseases Institute and Program in Infectious Diseases, Fred Hutchinson Cancer Research Center, 1616 Eastlake Avenue, LE-500, Seattle, WA 98102, USA.
3. Weill Cornell Medical College–Qatar, Cornell University, Doha, Qatar.
4. Department of Public Health, Weill Cornell Medical College, Cornell University, New York, NY 10021, USA.
5. Department of Laboratory Medicine, University of Washington, Seattle, WA 98195, USA.
6. Department of Biostatistics, University of Washington, Seattle, WA 98195, USA.
7. Department of Epidemiology, University of Washington, Seattle, WA 98195, USA.