1 Task Force for Global Health, Decatur, GA, USA. Electronic address: [email protected].
2 Immunization, Vaccines and Biologicals Department, World Health Organization, Geneva, Switzerland.
3 Epidemic and Pandemic Preparedness and Prevention Department, World Health Organization, Geneva, Switzerland.
4 Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Tropical Hygiene and Medicine, London, UK.