Marietjie Venter, Juan Yang, Simona Puzelli, Antonino Bella, Joshua A. Mott, Rodrigo Fasce, Coulibaly Daouda, Jenny Lara, Hongjie Yu, Winston Andrade, Selim Badur, Cláudio Maierovitch Pessanha Henriques, François G. Schellevis, Jean-Michel Heraud, Akerke Ospanova, Sonam Wangchuk, Brechla Moreno, Herve A. Kadjo, Raymond T. P. Lin, Juan Manuel Rudi, Walquiria Aparecida Ferreira de Almeida, Gabriela Kusznierz, Joseph S. Bresee, Cheryl Cohen, Mai thi Quynh Le, Rhonda Owen, Maria Zambon, Maria Luisa Matute, Kunzang Dorji, Kate Pennington, Global Influenza B Study, Herman Kosasih, Nurhayati, Alla Mironenko, Ming Li, Angel Balmaseda, Alexey Clara, Alfredo Bruno, Richard Njouom, Phuong Vu Mai Hoang, Ana Paula Rodrigues, Celina de Lozano, Luzhao Feng, Olha Holubka, Amal Barakat, Lyazzat Kiyanbekova, Norosoa Harline Razanajatovo, Saverio Caini, Meral Akcay Ciblak, Raquel Guiomar, Richard Pebody, Leticia Castillo, Gideon O. Emukule, Liza Lopez, Doménica de Mora, Jeffery Cutter, Q. Sue Huang, Marie-Astrid Vernet, Abderrahman Bimohuen, John Paget, Lynnette Brammer, General practice, EMGO - Quality of care, Netherlands Institute for Health Services Research, Instituto de Salud Pública de Chile (ISP), Istanbul University, Ministry of Health [Nicaragua] (MINSA), Ministry of Health [Morocco], Istituto Superiore di Sanita [Rome], Centers for Disease Control and Prevention [Atlanta] (CDC), Centers for Disease Control and Prevention, Instituto Nacional de Investigación en Salud Pública [Guayaquil, Ecuador] (INSPI), Ministerio de Salud Publica y Asistencia Social [Guatemala] (MSPAS), US Centers for Disease Control, University of the Witwatersrand [Johannesburg] (WITS), Ministry of Health, Institut Pasteur de Côte d'Ivoire, Réseau International des Instituts Pasteur (RIIP), Ministerio de Salud de El Salvador (MINSAL), Ministry of Health [Bhoutan], US Centers for Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Instituto nacional de saude, Unité de Virologie [Antananarivo, Madagascar] (IPM), Institut Pasteur de Madagascar, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP), National Academy of Medical Sciences of Ukraine, Institute of Environmental Science and Research (ESR), Astana Center of Sanitary Epidemiology Expertise, US Naval Medical Research Unit n°2, Instituto Nacional de Enfermedades Respiratorias 'Dr. Emilio Coni', Ministry of Health [Costa Rica], National Institute of Hygiene and Epidemiology [Hanoi, Vietnam] (NIHE), Ministry of Health [Honduras] (SESAL), National Influenza Center, Centre Pasteur du Cameroun, Office of Health Protection, Woden, ACT, Australia (DHAISS), Public Health England [London], National Institute of Health, University of Pretoria [South Africa], The Global Influenza B Study is supported by an unrestricted research grant from Sanofi Pasteur. The study sponsor had no role in the design of the study, in the collection, analysis, and interpretation of data, in the writing of the report, and and in the decision to submit the paper for publication. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication. The study sponsor had no access to the data in the study.