title: Influenza-like illness outbreaks in nursing homes in Corsica, France, 2014-2015: epidemiological and molecular characterization.
abstract: BACKGROUND
  To study the molecular epidemiology of the influenza outbreaks in nursing homes (NHs) to determine whether multiple influenza strains were involved.
  
  
  METHODS
  From September to December 2014, NHs in Corsica were invited to participate in an ongoing daily epidemiological and microbiological surveillance for influenza-like illness (ILI) among residents and health care workers (HCWs).
  
  
  RESULTS
  The study involved 12 NHs. Respiratory illness meeting the ILI case definition was observed among 44 residents from whom 22 specimens were collected. Of the 22 residents with a nasopharyngeal sample, 13 (59 %) were positive for at least one of the 11 pathogens analysed. Among these 13 patients, 11 (92 %) presented a confirmed influenza (A/H3N2) and two had another respiratory virus: one human metapneumovirus and one human coronavirus. Of patients with a confirmed influenza A(H3N2), 10 (91 %) were vaccinated against influenza during the 2014-2015 season. Two influenza outbreaks were reported in two NHs, caused by influenza A(H3N2) strains belonging to cluster 3C.3 and 3C.2a. Although antivirals were available, prophylaxis was not used.
  
  
  CONCLUSIONS
  Phylogenetic analysis seems to suggest no multiple introduction into the two NHs reporting the two influenza A(H3N2) outbreaks. A number of factors could have contributed to transmitting influenza in NHs including, the absence of administration of antiviral treatment for prophylaxis of all residents/staff regardless of immunization status because of the poor vaccine match during each outbreak, the intensive contacts with incompletely protected residents and HCWs, and the low adherence of NHs to notification of ILI outbreaks to the health authorities.
authors: EA 7310, Laboratory of Virology, University of Corsica-Inserm, Corte, France.
authors: S
authors: S
authors: Masse
authors: EA 7310, Laboratory of Virology, University of Corsica-Inserm, Corte, France.
authors: L
authors: L
authors: Minodier
authors: CIRE-SUD Paca Corse, InVS, Saint-Maurice Cedex, Paris, France.
authors: G
authors: G
authors: Heuze
authors: UPMC Univ Paris 06, UMR_S 1136, Sorbonne Universités, Paris, France ; INSERM, UMR_S 1136, Paris, France.
authors: T
authors: T
authors: Blanchon
authors: EA 7310, Laboratory of Virology, University of Corsica-Inserm, Corte, France ; UPMC Univ Paris 06, UMR_S 1136, Sorbonne Universités, Paris, France ; INSERM, UMR_S 1136, Paris, France.
authors: L
authors: L
authors: Capai
authors: EA 7310, Laboratory of Virology, University of Corsica-Inserm, Corte, France.
authors: A
authors: A
authors: Falchi
keywords: Elderly; Influenza; Influenza-like illness; Nursing homes; Outbreak