Umberto Restelli1, Davide Croce, Giuliano Rizzardini. 1. aCentre for Research on Health Economics, Social and Healthcare Management (CREMS), LIUC - Università Cattaneo, Castellanza, Italy bSchool of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa cFirst and Second Divisions of Infectious Diseases, 'Luigi Sacco' Hospital, Milan, Italy dSchool of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.