2 World Health Organization, Geneva, Switzerland. [email protected].
3 Integrated Research Facility at Fort Detrick, Division of Clinical Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, MD, USA.
4 Quadram Institute Bioscience, University of East Anglia, Norwich, UK.
5 European Centre for Disease Prevention and Control, Stockholm, Sweden.
6 Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
7 National Institute for Communicable Diseases, Johannesburg, South Africa.
8 School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.