In 1965, the 456 provided an anti-virus to the British government in exchange for twelve children. This anti-virus functioned as a cure for a new strain of Indonesian influenza which threatened to kill millions.
In 2009, Ianto Jones demanded that the 456 ambassador release an anti-virus following his release of a virus throughout Thames House in response to Jack Harkness' declaration of war, threatening to shoot his glass tank if he did not. However, the ambassador did not comply, his tank withstanding gunfire, resulting in the deaths of the vast majority of the people within Thames House including Ianto and, temporarily, Jack. (TV: Children of Earth: Day Four)