1 Department of Pediatrics, Section of Infectious Diseases, University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO, USA.
2 Department of Ecology, Evolutionary Biology and Public Affairs, Princeton University, Princeton, NJ, USA.
3 Department of Pediatrics, Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
4 Department of Pediatrics, Weill Cornell Medical College and New York-Presbyterian Hospital, New York, NY, USA.
5 Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.