ABSTRACT
Introduction: The Istituto Superiore di Sanita and the Agenzia Italiana del Farmaco coordinate the project TheShinISS-Vax, Flu, a post-marketing "active" surveillance of influenza vaccines. We report the results of the investigation using the Self- Controlled Case Series (SCCS) design on influenza vaccine and Guillain-Barre syndrome in vaccinated population aged over than 6 months, during the influenza vaccine campaign 2020-2021 in Italy. Materials and methods: A SCCS multi-regional study was carried out using linked data from Regional Health Care Registries of Valle d'Aosta, Friuli Venezia Giulia, Emilia-Romagna, Toscana, Lazio, Campania, and Puglia. Relative incidence of Guillain-Barre syndrome was estimated, comparing the exposure risk periods (0-41 days from the vaccination day, subdivided in six intervals) with the unexposed period.