Spillover is literally the transmission of a virus from one “reservoir” species, in which it habitually circulates, to a new “host” species, in which it can die or adapt and possibly even trigger an epidemic. Examples include SARS-CoV-2, Ebola, HIV, measles and seasonal flu viruses. The jump from an animal to a human requires three distinct phases: contact, infection and transmission.

Find out in detail how a spillover works in this video produced by the Istitituto Zooprofilattico Sperimentale delle Venezie (IZSVe), an Italian health authority and research organization for animal health and food safety.