John Paget, Olga Bessonova, Joseph S. Bresee, Norosoa Harline Razanajatovo, Saverio Caini, Binay Thapa, Francisco José de Paula Júnior, Jenny Lara Araya, Florette K. Treurnicht, Walquiria Aparecida Ferreira de Almeida, Brechla Moreno Arévalo, Zhibin Peng, Raquel Guiomar, Gabriela Kusznierz, Q. Sue Huang, Herman Kosasih, Antonino Bella, Doménica de Mora, Rakhee Palekar, Olha Holubka, Maria R. Castrucci, Rudevelinda Rivera, Phuong Vu Mai Hoang, Gideon O. Emukule, Rodrigo Fasce, Rocio Higueros, Sandra S. Chaves, Fatima el Falaki, Mai T. Q. Le, Herve A. Kadjo, Patricia Bustos, Luzhao Feng, Ainash Makusheva, Vernon J. Lee, Richard Njouom, Ana Paula Rodrigues, Coulibaly Daouda, Gé Donker, Alfredo Bruno, Alla Mironenko, Cheryl Cohen, Jean-Michel Heraud, Li Wei Ang, Sonam Wangchuk, Mónica Jeannette Barahona de Gámez, Maria Zambon, Clotilde El Guerche-Séblain, Angel Balmaseda, Lynnette Brammer, Amal Barakat, Richard Pebody, Adam Meijer, Verònica Vera Garate, Tim Wood, Netherlands Institute for Health Services Research [Utrecht] (NIVEL), Instituto Nacional de Enfermedades Respiratorias Dr. Emilio Coni [Santa Fe, Argentina] (INER), Ministry of Health [Bhoutan], Ministry of Health [Brasília, Brazil], Centre Pasteur du Cameroun, Réseau International des Instituts Pasteur (RIIP), Instituto de Salud Pública de Chile (ISP), Chinese Center for Disease Control and Prevention, Ministry of Health [Costa Rica], Instituto Nacional de Investigación en Salud Pública [Guayaquil, Ecuador] (INSPI), Ministerio de Salud de El Salvador (MINSAL), Public Health England [London], Ministerio de Salud Publica y Asistencia Social [Guatemala] (MSPAS), Ministry of Health [Honduras] (SESAL), US Naval Medical Research Unit No.2 [Jakarta, Indonesia] (NAMRU-2), Naval Medical Research Center [Silver Spring, USA] (NMRC), Istituto Superiore di Sanita [Rome], Institut Pasteur de Côte d'Ivoire, Institut National de Santé Publique d'Abidjan-INSP, Ministry of Healthcare [Kazakhstan], Centers for Disease Control and Prevention [Atlanta] (CDC), Centers for Disease Control and Prevention, Centers for Disease Control and Prevention [Kenya], Unité de Virologie [Antananarivo, Madagascar] (IPM), Institut Pasteur de Madagascar, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP), Institut National d'Hygiène [Maroc], National Institute for Public Health and the Environment [Bilthoven] (RIVM), Institute of Environmental Science and Research (ESR), Ministry of Health [Nicaragua] (MINSA), Pan American Health Organization [Washington] (PAHO), Instituto Conmemorativo Gorgas de Estudios de la Salud [Panamá], Instituto Nacional de Saùde Dr Ricardo Jorge [Portugal] (INSA), Ministry of Health [Singapore], National Institute for Communicable Diseases [Johannesburg] (NICD), University of the Witwatersrand [Johannesburg] (WITS), National Academy of Sciences of Ukraine (NASU), National Institute of Hygiene and Epidemiology [Hanoi, Vietnam] (NIHE), Sanofi Pasteur [Lyon, France], The study is supported by a research grant from Sanofi Pasteur: the ‘Global Epidemiology of Influenza B’ research project. The funder provided support in the form of salaries for two authors (CEGS and JP) but did not have any additional role in the data collection, analysis, decision to publish, or preparation of the manuscript., The 'Global Influenza B Study team' (group authorship) includes the following scientists: Juan Manuel Rudi (jmrudi@anlis.gov.ar), National Institute of Respiratory Diseases 'Emilio Coni', Santa Fe, Argentina, Dorji Wangchuk (dorjiwangchuk@health.gov.bt) and Sangay Zangmo (szangmo@health.gov.bt), Royal Centre for Disease Control, Department of Public Health, Ministry of Health, Thimphu, Bhutan, Daiana Araujo da Silva (daiana.silva@saude.gov.br), Ministry of Health, Department of Surveillance of Transmissible Diseases, Brasília/DF, Brazil, Winston Andrade (wandrade@ispch.cl), Sub-Department of Viral Diseases, Instituto de Salud Pública de Chile, Santiago, Chile, Jiandong Zheng (zhengjd@chinacdc.cn) and Ying Qin (qinying@chinacdc.cn), Division of Infectious Diseases, Chinese Center for Disease Control and Prevention, Beijing, P.R. China, Joanna Ellis (joanna.ellis@phe.gov.uk), Public Health England, London, United Kingdom, Simona Puzelli (simona.puzelli@iss.it), National Influenza Center, Department of Infectious Diseases, National Institute of Health, Rome, Italy, Caterina Rizzo (rizzocaterina@gmail.com), Bambino Gesù Children's Hospital, Rome, Italy, Linus Ndegwa (ikf7@cdc.gov), Influenza Program, Centers for Disease Control and Prevention, Nairobi, Kenya, Marit MA de Lange (marit.de.lange@rivm.nl) and Anne C. Teirlinck (anne.teirlinck@rivm.nl), National Institute for Public Health and the Environment, Centre for Infectious Diseases, Epidemiology and Surveillance, Bilthoven, The Netherlands, Jeffery Cutter (jeffery_cutter@moh.gov.sg) and Raymond Tzer Pin Lin (raymond_lin@moh.gov.sg), Public Health Group, Ministry of Health, Singapore, Singapore, Than T. Le (lmot82@yahoo.com), National Institute of Hygiene and Epidemiology, Hanoi, Vietnam, and Peter Kinuthia 42 (polorien@gmail.com), IHRC Inc., Atlanta, USA.