1Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA

2Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA

3PATH, Washington, DC, USA

4Center for Immunization Research, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA

5Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA

6Vaccine Testing Center, Larner College of Medicine, The University of Vermont, Burlington, VT, USA

7Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA

8Bacterial Disease Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA

9Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway

10Department of Clinical Science, University of Bergen, Bergen, Norway

11Kenya Medical Research Institute and United States Army Medical Research Directorate-Africa, Kericho, Kenya

12Henry M. Jackson Foundation Medical Research International, Bethesda, MD, USA

Chad K Porter, Enteric Diseases Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA. Email: [email protected]