In epidemiology, infectivity refers to the ability of a pathogen to establish an infection. It should be contrasted with virulence, which refers to the damage done by the pathogen once the infection is established.
It is closely related to the concept of incidence, which is the measure of infectivity in a population.
infectivity in German: Infektiosität
infectivity in Italian: Infettività
infectivity in Dutch: Besmettelijkheid
infectivity in Polish: Zakaźność