title: Influenza B burden during seasonal influenza epidemics in France.
abstract: BACKGROUND
  Seasonal flu outbreaks are linked to the circulation of influenza virus type A or B. Special attention has always been paid to influenza A epidemics; but recently, several studies have investigated the impact of influenza B virus epidemics, particularly as, since the 1980s, two antigenically different influenza B lineages co-circulate, raising the issue of vaccine matching.
  
  
  OBJECTIVE
  We present the results of influenza B burden during nine influenza seasons (2003-2013) and vaccine matching of the circulating lineages.
  
  
  METHODS
  Clinical and virological influenza surveillance data, collected by the Regional Groups for Influenza Surveillance Network in France, allows for studying the burden of influenza in the practice of the population of ambulatory care physicians.
  
  
  CONCLUSIONS
  Our analysis is based on 37,801 samples, of which 12,036 were virologically confirmed influenza cases (31.8%), including 3576 cases of influenza B (29.7% of influenza cases). Influenza B viruses significantly circulated during six seasons. For each season, the influenza B epidemic peaked later than the influenza A epidemic. Influenza B is very common in children of school age but also affects other age groups. Finally, more than one-third of the analyzed influenza B viruses belonged to a different lineage than the one used in the composition of the trivalent vaccine. Our results are comparable to those described in other countries.
authors.affiliation: Open Rome, 67, rue du Poteau, 75018 Paris, France. Electronic address: amos@openrome.org.
authors.forename: A
authors.initials: A
authors.lastname: Mosnier
authors.affiliation: Open Rome, 67, rue du Poteau, 75018 Paris, France.
authors.forename: I
authors.initials: I
authors.lastname: Daviaud
authors.affiliation: Centre national de référence des virus influenza, CBPE, hospices civils de Lyon et Virpath, université Claude-Bernard Lyon, 69000 Lyon, France.
authors.forename: J S
authors.initials: JS
authors.lastname: Casalegno
authors.affiliation: Réseau des Groupes régionaux d'observation de la grippe (GROG), 75018 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Ruetsch
authors.affiliation: Réseau des Groupes régionaux d'observation de la grippe (GROG), 75018 Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Burugorri
authors.affiliation: Open Rome, 67, rue du Poteau, 75018 Paris, France.
authors.forename: E
authors.initials: E
authors.lastname: Nauleau
authors.affiliation: Open Rome, 67, rue du Poteau, 75018 Paris, France.
authors.forename: T T
authors.initials: TT
authors.lastname: Bui
authors.affiliation: Laboratoire de virologie, hôpital Pellegrin, 33000 Bordeaux, France.
authors.forename: H
authors.initials: H
authors.lastname: Fleury
authors.affiliation: Centre national de référence des virus influenza, CBPE, hospices civils de Lyon et Virpath, université Claude-Bernard Lyon, 69000 Lyon, France.
authors.forename: B
authors.initials: B
authors.lastname: Lina
authors.affiliation: Centre national de référence des virus influenza, génétique moléculaire des virus respiratoires, Institut Pasteur, CNRS UMR 3569, université Paris Diderot Sorbonne Paris-Cité, 75015 Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: van der Werf
authors.affiliation: Open Rome, 67, rue du Poteau, 75018 Paris, France.
authors.forename: J M
authors.initials: JM
authors.lastname: Cohen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005602:France / Q000453:epidemiology; D006801:Humans; D009981:Influenza B virus; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control; D008875:Middle Aged; D012621:Seasons; D013997:Time Factors; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Flu outbreak; France; Grippe B; Influenza B; Épidémie de grippe