title: Adverse events following immunization: real causality and myths.
abstract: BACKGROUND
  To assure the highest safety of immunization programs, detect adverse events following immunization (AEFIs), eliminate concerns, and reduce the risk of low vaccination coverage, authorities in industrialized countries have collected years of reports of suspected AEFIs and have systematically assessed their clinical importance.
  
  
  METHODS
  In this paper, the methods used to assess vaccine safety and the results obtained by the analysis of reports, studies, and meta-analyses are discussed.
  
  
  CONCLUSIONS
  Severe AEFIs are rare, and all evaluations of safety of vaccines recommended for both children and adults have demonstrated that the advantages of vaccines are always significantly higher than the problems that they cause, and there is no need to modify recommendations. However, the definition of AEFI is dependent on the vaccines themselves, complicating the definition of an AEFI and explaining why doubts and concerns have been raised. Presently, disease epidemiology data collected in healthy people and in subjects with underlying disease, general vaccine coverage, and the vaccination status of subjects with AEFIs are managed by many independent institutions. Only strict co-operation between these institutions will lead to the successful identification of AEFIs and to a reduction of the weight of anti-vaccine arguments.
authors.affiliation: a Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation , Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico , Milan , Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Principi
authors.affiliation: a Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation , Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico , Milan , Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Esposito
mesh_terms: D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D002648:Child; D006801:Humans; D007114:Immunization / Q000009:adverse effects*; D014611:Vaccination / Q000009:adverse effects*; D014612:Vaccines / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D014612:Vaccines
keywords: AEFI; adverse event; immunization; prevention; reactogenicity; tolerability; vaccine