1 Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland; The Vaccine Centre, London School of Hygiene and Tropical Medicine, London, UK. Electronic address: edward.parker@lshtm.ac.uk.
2 Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland.
3 Department of Health Security at the Finnish Institute for Health and Welfare, Helsinki, Finland.
4 PATH Essential Medicines, PATH, Seattle, Washington, USA.
5 Global Healthcare Consulting, New Delhi, India; Department of Global Health, University of Washington, Seattle, Washington, USA.
6 Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland; Institute of Social and Preventive Medicine, University of Berne, Berne, Switzerland; Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany.