Active surveillance of adverse events after immunization (AEFI) from the Local Health Unitof Ferrara, Italy.

Introduction: Vaccine vigilance implies the collection, evaluation, analysis and communication of adverse events following immunization (AEFI) and is a useful tool for vaccine monitoring allowing, even after approval and marketing, to check its safety/tolerability. The multiregional project "Active surveillance of adverse vaccine reactions", joined by the AUSL of Ferrara, is aimed at making parents of children, who have undergone at least one vaccination provided by the regional vaccination calendar in the first 24 months of life, aware of the reporting of any AEFI via mobile phone-SMS.

Methods: An analysis of the project data, collected in the period March 2018 - May 2019, was carried out, to evaluate the effectiveness of the reporting tool and the type and frequency of AEFI. Anonymized data were analyzed by number, gender, distribution by age, type of vaccine, adverse event, severity and outcome.

Results: A total of 1,494 consents and 983 SMS messages were obtained from parents. The vaccine doses carried out were 1,984 (28.3% hexavalent, 28% PCV13, 17% anti-rotavirus, 14.3% Men-B). Almost all (99.5%) AEFI were classified as "not serious". Based on the Organ System Class (SOC), most reports are related to "General Disorders and Administration Site Conditions" (52.3%), followed by "Psychiatric Disorders" (26.5%) and "Metabolic and nutrition disorders" (12.5%).

Conclusions: The reported AEFI are in line with the ones reported in the literature. Reporting via SMS is a valid vaccine surveillance tool contributing to the qualitative and quantitative improvement of the information transmitted.