title: A systematic review of the evidence on the effectiveness and risks of inactivated influenza vaccines in different target groups.
abstract: OBJECTIVE
  To systematically review the evidence regarding the efficacy, effectiveness and risks of the use of inactivated influenza vaccines in children, healthy adults, elderly individuals and individuals with co-morbidities such as diabetes, chronic lung disease, cardiovascular disease, kidney or liver disease and immune suppression.
  
  
  METHODS
  The Cochrane database of systematic reviews was searched for relevant reviews and supplemented with searches of the Cochrane Central Register of Controlled Trials database and Medline. Two reviewers independently assessed review and trial quality and extracted data.
  
  
  CONCLUSIONS
  The inactivated influenza vaccine has been proven effective in preventing laboratory-confirmed influenza among healthy adults (16-65 years) and children (≥6 years) (GRADE A evidence). However, there is strikingly limited good-quality evidence (all GRADE B, C or not existing) of the effectiveness of influenza vaccination on complications such as pneumonia, hospitalisation and influenza-specific and overall mortality. Inconsistent results are found in studies among children younger than 6 years, individuals with COPD, institutionalised elderly (65 years or older), elderly with co-morbidities and healthcare workers in elderly homes, which can only be explained by bias of unknown origin. The vaccination of pregnant women might be beneficial for their newborns, and vaccination of children might be protective in non-recipients of the vaccine of all ages living in the same community (one RCT, Grade B evidence).
authors.affiliation: Department of Primary and Interdisciplinary Care, Centre for General Practice, Faculty of Medicine, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium. barbara.michiels@ua.ac.be
authors.forename: Barbara
authors.initials: B
authors.lastname: Michiels
authors.forename: Frans
authors.initials: F
authors.lastname: Govaerts
authors.forename: Roy
authors.initials: R
authors.lastname: Remmen
authors.forename: Etienne
authors.initials: E
authors.lastname: Vermeire
authors.forename: Samuel
authors.initials: S
authors.lastname: Coenen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic; D015897:Comorbidity; D005260:Female; D006282:Health Personnel; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007251:Influenza, Human / Q000517:prevention & control*; D008875:Middle Aged; D011247:Pregnancy; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines; D015164:Vaccines, Inactivated