Past experience with vaccinia provides evidence that it poses a health risk to humans and non-humans. Vaccinia is a minor human pathogen causing illness and even death in susceptible people, including the very young and people with immunodeficiency. Unintentionally, however, they may be taking part in an uncontrolled experiment. For example, Raboral V-RG could be transmitted to them via their pet cats which have either eaten the bait themselves or preyed on small mammals which have eaten it. Although intended for foxes, any animal can eat the bait containing Raboral V-RG, including small mammals, birds, domestic pets and livestock.
Vaccinia has a broad host range which includes humans, small mammals and livestock.
It is possible that Raboral V-RG will colonise animals which eat the bait. Moreover, when vaccinia was used as a smallpox vaccine, it spread from vaccinated humans to non-vaccinated humans and other animals. Thus there is a risk that Raboral V-RG may be transmitted from one animal to another. This is alleged to have happened when Raboral V-RG was used in in Argentina, where it is claimed it was transmitted from vaccinated cows to human workers. Vaccinia is not genetically stable.