1. Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta; Neuroepidemiology Unit; via Celoria, 11 Milano Italy 20133
2. University of Modena and Reggio Emilia; Statistics Unit, Department of Clinical and Diagnostic Medicine and Public Health; Modena Italy
3. Scientific Institute and University Ospedale San Raffaele; Institute of Experimental Neurology (INSPE); via Olgettina 58 Milano Italy
4. Azienda Sanitaria Locale ASL AL; Servizio Regionale di Riferimento per l'Epidemiologia, SSEpi-SeREMI - Cochrane Vaccines Field; Via Venezia 6 Alessandria Piemonte Italy 15100
5. London School of Hygiene & Tropical Medicine; Cochrane Injuries Group; Keppel Street London UK WC1E 7HT
6. University of Ioannina School of Medicine; Department of Hygiene and Epidemiology; Medical School Campus University of Ioannina Ioannina Greece 45110