title: Epidemiological and virological characteristics of influenza B: results of the Global Influenza B Study.
abstract: BACKGROUND
  Literature on influenza focuses on influenza A, despite influenza B having a large public health impact. The Global Influenza B Study aims to collect information on global epidemiology and burden of disease of influenza B since 2000.
  
  
  METHODS
  Twenty-six countries in the Southern (n = 5) and Northern (n = 7) hemispheres and intertropical belt (n = 14) provided virological and epidemiological data. We calculated the proportion of influenza cases due to type B and Victoria and Yamagata lineages in each country and season; tested the correlation between proportion of influenza B and maximum weekly influenza-like illness (ILI) rate during the same season; determined the frequency of vaccine mismatches; and described the age distribution of cases by virus type.
  
  
  RESULTS
  The database included 935 673 influenza cases (2000-2013). Overall median proportion of influenza B was 22·6%, with no statistically significant differences across seasons. During seasons where influenza B was dominant or co-circulated (>20% of total detections), Victoria and Yamagata lineages predominated during 64% and 36% of seasons, respectively, and a vaccine mismatch was observed in ≈25% of seasons. Proportion of influenza B was inversely correlated with maximum ILI rate in the same season in the Northern and (with borderline significance) Southern hemispheres. Patients infected with influenza B were usually younger (5-17 years) than patients infected with influenza A.
  
  
  CONCLUSIONS
  Influenza B is a common disease with some epidemiological differences from influenza A. This should be considered when optimizing control/prevention strategies in different regions and reducing the global burden of disease due to influenza.
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.
authors.forename: Saverio
authors.initials: S
authors.lastname: Caini
authors.affiliation: Institute of Environmental Science and Research, Wellington, New Zealand.
authors.forename: Q Sue
authors.initials: QS
authors.lastname: Huang
authors.affiliation: Istanbul University, Istanbul, Turkey.
authors.forename: Meral A
authors.initials: MA
authors.lastname: Ciblak
authors.affiliation: Instituto Nacional de Enfermedades Respiratorias Dr. Emilio Coni, Santa Fe, Argentina.
authors.forename: Gabriela
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authors.lastname: Kusznierz
authors.affiliation: Department of Health and Ageing, Influenza Surveillance Section, Surveillance Branch, Office of Health Protection, Woden, ACT, Australia.
authors.forename: Rhonda
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authors.lastname: Owen
authors.affiliation: Public Health Laboratory, Department of Public Health, Ministry of Health, Thimphu, Bhutan.
authors.forename: Sonam
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authors.lastname: Wangchuk
authors.affiliation: Ministry of Health, Brasília, DF, Brazil.
authors.forename: Cláudio M P
authors.initials: CM
authors.lastname: Henriques
authors.affiliation: Service de Virologie, Centre Pasteur du Cameroun, Yaounde, Cameroon.
authors.forename: Richard
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authors.lastname: Njouom
authors.affiliation: Sección de Virus Respiratorios y Exantemáticos, Instituto de Salud Pública de Chile, Santiago de Chile, Chile.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Fasce
authors.affiliation: Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yu
authors.affiliation: Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Luzhao
authors.initials: L
authors.lastname: Feng
authors.affiliation: Respiratory Virus Unit, Public Health England, Colindale, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Zambon
authors.affiliation: US Centers for Disease Control, Central American Region, Guatemala City, Guatemala.
authors.forename: Alexey W
authors.initials: AW
authors.lastname: Clara
authors.affiliation: US Naval Medical Research Unit No. 2, Jakarta, Indonesia.
authors.forename: Herman
authors.initials: H
authors.lastname: Kosasih
authors.affiliation: National Influenza Center, Istituto Superiore Sanità, Rome, Italy.
authors.forename: Simona
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authors.lastname: Puzelli
authors.affiliation: Respiratory Viruses Unit, Pasteur Institute of Côte d'Ivoire, Abidjan, Côte d'Ivoire.
authors.forename: Herve A
authors.initials: HA
authors.lastname: Kadjo
authors.affiliation: US Centers for Disease Control and Prevention, Nairobi, Kenya.
authors.forename: Gideon
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authors.lastname: Emukule
authors.affiliation: National Influenza Center, Virology Unit, Institut Pasteur of Madagascar, Antananarivo, Madagascar.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Heraud
authors.affiliation: Epidemiology and Disease Control Division, Ministry of Health, Singapore, Singapore.
authors.forename: Li Wei
authors.initials: LW
authors.lastname: Ang
authors.affiliation: Global Disease Detection, US-CDC, Pretoria, South Africa.|Zoonoses Research Unit, Department of Medical Virology, University of Pretoria, Pretoria, South Africa.
authors.forename: Marietjie
authors.initials: M
authors.lastname: Venter
authors.affiliation: L.V.Gromashevsky Institute of Epidemiology and Infectious Diseases National Academy of Medical Science of Ukraine, Kiev, Ukraine.
authors.forename: Alla
authors.initials: A
authors.lastname: Mironenko
authors.affiliation: Epidemiology and Prevention Branch, Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Lynnette
authors.initials: L
authors.lastname: Brammer
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Le Thi Quynh
authors.initials: le TQ
authors.lastname: Mai
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.
authors.forename: François
authors.initials: F
authors.lastname: Schellevis
authors.affiliation: University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Plotkin
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, The Netherlands.
authors.forename: John
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mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D005260:Female; D014943:Global Health; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus; D009981:Influenza B virus / Q000235:genetics; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012621:Seasons; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Burden of disease; Global Influenza B Study (GIBS); epidemiology; influenza; vaccination; vaccine mismatch