[1] WHO, Dept Immunizat Vaccines & Biol, Geneva, Switzerland
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Int Hlth, Baltimore, MD USA
[3] World Hlth Org Reg Off Africa, Intersupport Team East & South Africa, Dept Immunizat Vaccines & Biol, Harare, Zimbabwe
[4] Pan Amer Hlth Org, Dept Family Hlth Promot & Life Course, World Hlth Org Reg Off Amer, Comprehens Family Immunizat Unit, Washington, DC USA
[5] World Hlth Org Eastern Mediterranean Off, Dept Communicable Dis, Immunizat Vaccines & Biolog Unit, Cairo, Egypt
[6] World Hlth Org Eastern Reg Off, Vaccine Preventable Dis & Immunizat Unit, Div Country Hlth Programmes, Copenhagen, Denmark
[7] World Hlth Org South East Asia Reg Off, Dept Immunizat & Vaccine Dev, New Delhi, India
[8] World Hlth Org Western Pacific Reg Off, Div Programmes Dis Control, Vaccine Preventable Dis & Immunizat, Manila, Philippines
[9] London Sch Hyg & Trop Med, Dept Infect Dis Epidemiol, London, England
[10] Nagasaki Univ, Sch Trop Med & Global Hlth, Nagasaki, Japan