title: Effect of influenza vaccination on the prognosis of hospitalized influenza patients.
abstract: OBJECTIVE
  This study aimed to assess whether influenza vaccination reduces the risk of severe and fatal outcomes in influenza inpatients aged ≥65 years.
  
  
  METHODS
  During the 2013-2014 influenza season persons aged ≥65 years hospitalized with laboratory-confirmed influenza were selected in 19 Spanish hospitals. A severe influenza case was defined as admission to the intensive care unit, death in hospital or within 30 days after admission. Logistic regression was used to compare the influenza vaccination status between severe and non-severe influenza inpatients.
  
  
  RESULTS
  Of 433 influenza confirmed patients, 81 (19%) were severe cases. Vaccination reduced the risk of severe illness (odds ratio: 0.57; 95%CI: 0.33-0.98). The cumulative number of influenza vaccine doses received since the 2010-2011 season was associated with a lower risk of severe influenza (odds ratio: 0.78; 95% CI 0.66-0.91).
  
  
  CONCLUSIONS
  Adherence to seasonal influenza vaccination in the elderly may reduce the risk of severe influenza outcomes.
authors.affiliation: a Instituto de Salud Pública de Navarra , IdiSNA - Navarra Institute for Health Research , Pamplona , Spain.
authors.forename: Itziar
authors.initials: I
authors.lastname: Casado
authors.affiliation: b CIBER Epidemiología y Salud Pública (CIBERESP) , Madrid , Spain.|c Departament de Salut Pública , Universitat de Barcelona , Barcelona , Spain.
authors.forename: Angela
authors.initials: A
authors.lastname: Domínguez
authors.affiliation: c Departament de Salut Pública , Universitat de Barcelona , Barcelona , Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: Toledo
authors.affiliation: d Servicio de Medicina Preventiva, Complejo Hospitalario de Navarra , Pamplona , Spain.
authors.forename: Judith
authors.initials: J
authors.lastname: Chamorro
authors.affiliation: e Unidad de Enfermedades Infecciosas, Hospital de Mataró , Mataró , Spain.
authors.forename: Lluis
authors.initials: L
authors.lastname: Force
authors.affiliation: b CIBER Epidemiología y Salud Pública (CIBERESP) , Madrid , Spain.|c Departament de Salut Pública , Universitat de Barcelona , Barcelona , Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Soldevila
authors.affiliation: f Dirección de Salud Pública, Consejería de Sanidad , Madrid , Spain.
authors.forename: Jenaro
authors.initials: J
authors.lastname: Astray
authors.affiliation: g Servicio de Neumología, Hospital de Galdakao , Usansolo , Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Egurrola
authors.affiliation: b CIBER Epidemiología y Salud Pública (CIBERESP) , Madrid , Spain.|h Agència de Salut Pública de Catalunya , Barcelona , Spain.|i Institut de Recerca Biomèdica de Lleida , Universitat de Lleida , Lleida , Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Godoy
authors.affiliation: j Servicio de Vigilancia, Junta de Andalucía , Sevilla , Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Mayoral
authors.affiliation: k Dirección General de Salud Pública, Investigación, Desarrollo e Innovación , Valladolid , Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Tamames
authors.affiliation: l Servicio de Neumología, Consorci Hospital General Universitari de Valencia , Valencia , Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Sanz
authors.affiliation: a Instituto de Salud Pública de Navarra , IdiSNA - Navarra Institute for Health Research , Pamplona , Spain.|b CIBER Epidemiología y Salud Pública (CIBERESP) , Madrid , Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Castilla
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003422:Critical Care; D005260:Female; D006760:Hospitalization; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D007251:Influenza, Human / Q000401:mortality* / Q000473:pathology* / Q000517:prevention & control / Q000628:therapy; D008297:Male; D011379:Prognosis; D013030:Spain; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D007252:Influenza Vaccines
keywords: Influenza virus; mortality; seasonal influenza vaccine; severe influenza; vaccine effectiveness