Netherlands Institute for Health Services Research (NIVEL), Otterstraat 118-124, 3513, CR, Utrecht, The Netherlands
Saverio Caini, Peter Spreeuwenberg, François Schellevis & John Paget
Instituto Nacional de Enfermedades Respiratorias “Dr. Emilio Coni”, Santa Fe, Argentina
Gabriela F. Kusznierz & Juan Manuel Rudi
Vaccine Preventable Diseases Surveillance Section, Health Policy Protection branch, Office for Health Protection, Department of Health, Woden, Canberra, Australia
Rhonda Owen & Kate Pennington
Public Health Laboratory, Department of Public Health, Ministry of Health, Thimphu, Bhutan
Sonam Wangchuk & Sonam Gyeltshen
Ministry of Health, Brasilia, DF, Brazil
Walquiria Aparecida Ferreira de Almeida & Cláudio Maierovitch Pessanha Henriques
Virology Department, Centre Pasteur of Cameroon, Yaoundé, Cameroon
Richard Njouom & Marie-Astrid Vernet
Sección Virus Respiratorios, Instituto de Salud Pública de Chile, Santiago, Chile
Rodrigo A. Fasce & Winston Andrade
Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China
Hongjie Yu, Luzhao Feng, Juan Yang & Zhibin Peng
National Influenza Center, Ministry of Health, San José, Costa Rica
Jenny Lara
Instituto Nacional de Investigacion en Salud Publica (INSPI), Centro de Referencia Nacional de Influenza y otros Virus Respiratorios, Guayaquil, Ecuador
Alfredo Bruno & Doménica de Mora
National Influenza Center, Ministry of Health, San Salvador, El Salvador
Celina de Lozano
Respiratory Virus Unit, Public Health England, London, Colindale, UK
Maria Zambon
Respiratory Diseases Department, Public Health England, London, Colindale, UK
Richard Pebody
National Influenza Center, Ministry of Health, Guatemala City, Guatemala
Leticia Castillo
US Centers for Disease Control, Central American Region, Guatemala City, Guatemala
Alexey W. Clara
National Influenza Center, Ministry of Health, Tegucigalpa, Honduras
Maria Luisa Matute
US Naval Medical Research Unit No.2, Jakarta, Indonesia
Herman Kosasih & Nurhayati
National Influenza Center, National Institute of Health, Rome, Italy
Simona Puzelli
National Center for Epidemiology, Surveillance and Health Promotion, National Institute of Health, Rome, Italy
Caterina Rizzo
Department of Epidemic Virus, Institut Pasteur, Abidjan, Côte d’Ivoire
Herve A. Kadjo
Service of Epidemiological Diseases Surveillance, National Institute of Public Hygiene, Abidjan, Côte d’Ivoire
Coulibaly Daouda
National Center of Expertise, Committee of Consumer Right Protection, Astana, Kazakhstan
Lyazzat Kiyanbekova
Zonal Virology Laboratory, National Center of Expertise, Committee of Consumer Right Protection, Astana, Kazakhstan
Akerke Ospanova
Centers for Disease Control and Prevention - Kenya Country Office, Nairobi, Kenya
Joshua A. Mott & Gideon O. Emukule
US Public Health Service, Rockville, Maryland, USA
Joshua A. Mott
National Influenza Center, Virology Unit, Institut Pasteur of Madagascar, Antananarivo, Madagascar
Jean-Michel Heraud & Norosoa Harline Razanajatovo
National Influenza Center, Institut National d’Hygiène, Ministry of Health, Rabat, Morocco
Amal Barakat & Fatima el Falaki
Institute of Environmental Science and Research, Wellington, New Zealand
Sue Q. Huang & Liza Lopez
National Influenza Center, Ministry of Health, Managua, Nicaragua
Angel Balmaseda
National Influenza Center, IC Gorgas, Panama City, Panama
Brechla Moreno
Department of epidemiology, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
Ana Paula Rodrigues
National Influenza Reference Laboratory, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
Raquel Guiomar
Epidemiology and Disease Control Division, Ministry of Health, Singapore, Singapore
Li Wei Ang
Communicable Diseases Division, Ministry of Health, Singapore, Singapore
Vernon Jian Ming Lee
Global Disease Detection, US-CDC, Pretoria, South Africa
Marietjie Venter
Zoonoses Research Center, Department of Medical Virology, University of Pretoria, Pretoria, South Africa
Marietjie Venter
Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases, Johannesburg, South Africa
Cheryl Cohen
School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa
Cheryl Cohen
Istanbul University, Istanbul, Turkey
Selim Badur & Meral A. Ciblak
L.V.Gromashevsky Institute of Epidemiology and Infectious Diseases National Academy of Medical Science of Ukraine, Reiv, Ukraine
Alla Mironenko & Olha Holubka
Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
Joseph Bresee & Lynnette Brammer
National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
Phuong Vu Mai Hoang & Mai Thi Quynh Le
Independent scientist, Birmingham, UK
Douglas Fleming
Sanofi Pasteur, Lyon, France
Clotilde El-Guerche Séblain
Department of General Practice & Elderly Care Medicine, Amsterdam Public Health Research Institute, VU University Medical Center, Amsterdam, the Netherlands
François Schellevis
SC, JP, CEGS, PS and FS conceived the study. GFK, JMR, RO, KP, SW, SG, WAFdA, CMPH, RN, MAV, RAF, WA, HY, LF, JY, ZP, JL, AB, DdM, CdL, MZ, RP, LC, AWC, MLM, HK, N, SP, CR, HAK, CD, LK, AO, JAM, GOE, JMH, NHR, AB, FeF, SQH, LL, AB, BM, APR, RG, LWA, VJML, MV, CC, SB, MAC, AM, OH, JB, LB, PVMH, MTQL, DF and members of the Global Influenza B Study group collected the data. SC and PS performed the statistical analysis. SC, JP and CEGS interpreted the results. SC and JP wrote the first draft of the manuscript. All authors critically revised the manuscript and approved its final version.