title: [EVAN-50 study: Effectiveness of polysaccharide pneumococcus vaccine in preventing pneumococcal infections in the over-50 population].
abstract: OBJECTIVE
  To assess the effectiveness of 23-valent polysaccharide vaccine in preventing severe pneumococcal infections in adults over 50 years old.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Primary Health Care Service, Tarragona, Spain.
  
  
  METHODS
  A total of 270 patients >50 with severe pneumococcal disease (invasive pneumococcal disease and non-bacteraemic pneumococcal pneumonia) and 540 control patients randomized from the primary care Centres of the case patients. Case and control patients will be matched for age, sex, family physician, and level of risk for pneumonia.
  
  
  METHODS
  Odds ratio (OR) will be used to measure the vaccine effect. Multivariate logistical regression, adjusted for age, sex, and comorbidity, will be conducted. Vaccine effectiveness (VE) will be calculated by the formula, VE = 1-OR. Vaccine effectiveness will be distinguished for the various age groups and at each risk stratum. It will also be estimated by means of indirect cohort analysis, taking as cases the infection caused by vaccine serotypes and as controls infection caused by non-vaccine serotype.
  
  
  CONCLUSIONS
  The study will give an answer in terms of effectiveness of the vaccine for several age and risk strata. It will contribute to taking a decision regarding the controversial question of the systematic indication, or otherwise, of this vaccine for the elderly.
authors.affiliation: Servicio de Atención Primaria Tarragona-Valls, Gerencia de Ambito de Tarragona-Terres de l'Ebre, Institut Català de la Salut, Tarragona, España. avila.tarte.ics@gencat.net
authors.forename: Angel
authors.initials: A
authors.lastname: Vila Córcoles
authors.forename: Olga
authors.initials: O
authors.lastname: Ochoa Gondar
authors.forename: Elisabet
authors.initials: E
authors.lastname: Salsench Serrano
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Hospital Guardiola
authors.forename: Angels
authors.initials: A
authors.lastname: Vilanova Navarro
authors.forename: Xavier
authors.initials: X
authors.lastname: Raga Luria
mesh_terms: D016022:Case-Control Studies; D006801:Humans; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000627:therapeutic use*; D012107:Research Design; D014611:Vaccination / Q000379:methods
chemical_list: C414006:23-valent pneumococcal capsular polysaccharide vaccine; D022242:Pneumococcal Vaccines