[1
]
Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge,
Cambridge, UK. Electronic address: clt56@cam.ac.uk.
[2
]
Inter-country Support Team for West Africa, World Health Organization, Ouagadougou,
Burkina Faso.
[3
]
Department of Pandemic and Epidemic Diseases, World Health Organization, Geneva, Switzerland.
[4
]
Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge,
Cambridge, UK.
[5
]
Immunization and Vaccine Development Unit, Regional Office for Africa, World Health
Organization, Brazzaville, Congo.
[6
]
Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva,
Switzerland.
[7
]
Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine,
London, UK.