The article presents the results of an empirical research that addresses the issue of place vulnerability in the first three waves of the Covid-19 pandemic in Italy, discussing the spatial factors involved in the spread of the virus. Through a re-reading of the literature
on epidemic spatial diffusion, the usefulness of the principle of potential interaction for a strategic geography of public health is verified, assuming a public geography perspective. With reference to the different impact probabilities, the theoretically possible
types of spatial interaction are discussed, then the model elaborated is tested by means of experimentation in territories that differ in terms of interaction and spread modes. The results of the application to the territories of two Italian regions (Tuscany and Molise) characterised by a different socio-territorial organisation and differentiated diffusion dynamics, show how the variety of the territorial configurations present in Italy, characterised by the pervasiveness of interaction and by a multiple articulation of short and long networks, conditions epidemic diffusion. The analysis arrives at unexpected conclusions concerning the criticality of peripheral areas, often erroneously perceived as less vulnerable.