Original Research ARTICLE
Predictors of vaccines safety in children and in general population: 1-year pharmacovigilance study on adverse events following immunization
- 1Department of Neurosciences, Psychology, Drugs and Child Health Area, School of Psychology, University of Florence, Italy
- 2Department of Clinical and Experimental Medicine, University of Pisa, Italy
- 3Department of Medical, Surgical and Neuroscience Sciences, University of Siena, Italy
- 4CiaoLapo Onlus, Charity for Healthy Pregnancy, Stillbirth and Perinatal Grief Support, Italy
- 5Epidemiology Unit, Department of Prevention, Local Health Unit Tuscany Centre, Italy
- 6Meyer University Hospital, University of Florence, Italy
- 7Department of Health Sciences, School of Psychology, University of Florence, Italy
- 8University of Florence, Italy
Background: The fear of adverse events following immunization (AEFI), often supported by anti-vaccination movements and devoid of any scientific plausibility, have eroded confidence in vaccines. Thus, the aims of the present study were to characterize AEFI in general population, in terms of frequency, preventability and seriousness, and to define predictors of their seriousness in children.
Methods: A retrospective study was performed on suspected AEFI reports collected in Tuscany (Italy) in 2017. Patients’ characteristics, suspected vaccines, and AEFI description were collected. Causality and preventability were assessed using validated algorithms, and logistic regression was used to estimate the reporting odds ratios of potential predictors of AEFI seriousness in children.
Results: A total of 223 suspected AEFI reports were collected, and the majority of them were defined as non-serious (76.7%). Reports were mostly related to one vaccine, and to a median of 2-5 strains/toxoids. The total number of simultaneously administered strains/toxoids and the presence of allergens did not correlate with AEFI seriousness. Considering vaccines with a high number of administered doses (≥60,000 doses), the rates estimated for serious AEFI reports were always very low, ranging between 0.01 and 0.2/1,000 doses. Twenty-four vaccines (8,993 doses) were not related to any AEFI.
Conclusion: Results of present study show that AEFI are very rare, the vast majority of them is non-serious and, despite the claims of anti-vaccination movements, the simultaneous administration of vaccines is safe and does not influence the risk of reporting a serious AEFI, particularly in children.
Keywords: Vaccines, Adverse event following immunization (AEFI), Pharmacovigilance, Safety, Observational study, Preventability, Seriousness
Received: 01 Mar 2019;
Accepted: 24 Jul 2019.
Copyright: © 2019 Lombardi, Crescioli, Bettiol, Tuccori, Rossi, Bonaiuti, Ravaldi, Levi, Mugelli, Ricci, Lippi, Azzari, Bonanni and Vannacci. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Alfredo Vannacci, University of Florence, Florence, Italy, email@example.com