title: Epidemiology of influenza B in Australia: 2001-2014 influenza seasons.
abstract: Influenza B is characterised by two antigenic lineages: B/Victoria and B/Yamagata. These lineages circulate together with influenza A during influenza seasons, with varying incidence from year to year and by geographic region.
  
  
  
  To determine the epidemiology of influenza B relative to influenza A in Australia.
  
  
  
  Laboratory-confirmed influenza notifications between 2001 and 2014 in Australia were obtained from the Australian National Notifiable Diseases Surveillance System.
  
  
  
  A total of 278 485 laboratory-confirmed influenza cases were notified during the study period, comprising influenza A (82.2%), B (17.1%) and 'other and untyped' (0.7%). The proportion of notifications that were influenza B was highest in five- to nine-year-olds (27.5%) and lowest in persons aged 85 years and over (11.5%). Of all B notifications with lineage determined, 77.1% were B/Victoria and 22.9% were B/Yamagata infections. Mismatches between the dominant B lineage in a season and the trivalent vaccine B lineage occurred in over one-third of seasons during the study years. In general, influenza B notifications peaked later than influenza A notifications.
  
  
  
  The proportion of circulating influenza B in Australia during 2001-2014 was slightly lower than the global average and was dominated by B/Victoria. Compared with influenza A, influenza B infection was more common among older children and young adults and less common in the very elderly. Influenza B lineage mismatch with the trivalent vaccine occurred about one-third of the time.
authors.affiliation: School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Aye M
authors.initials: AM
authors.lastname: Moa
authors.affiliation: School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Muscatello
authors.affiliation: School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Robin M
authors.initials: RM
authors.lastname: Turner
authors.affiliation: School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia.|College of Public Service & Community Solutions, Arizona State University, Phoenix, Arizona, USA.
authors.forename: Chandini R
authors.initials: CR
authors.lastname: MacIntyre
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques; D005260:Female; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000276:immunology; D009981:Influenza B virus / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D011159:Population Surveillance; D012621:Seasons; D014739:Victoria / Q000453:epidemiology; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Australia; Victoria lineage; Yamagata lineage; epidemiology; influenza B