Classification bias and impact of COVID-19 vaccination on all-cause mortality: the case of the Italian region Emilia-Romagna. Marco Alessandria Giovanni Trambusti Giovanni Maria Malatesta Panagis Polykretis Alberto Donzelli a Department of Life Sciences and Systems Biology, University of Turin, Turin, Italyb Department of Theoretical and Applied Sciences, eCampus University, Novedrate, Italyc Scientific Committee of the “Allineare Sanità e Salute” Foundation, Milan, Italyd Independent Medical-Scientific Commission, Milan, Italy