Infection refers to the point when
growth energy begins to enter a person's body and starts to fill them up. As a result of being infected, a person's body basically becomes partial-energy. This is a side-effect of the growth energy's original intent as a super soldier serum and means someone who's growing will be immune to a lot of things that would harm a regular person. They won't be hurt by collapsing buildings, they are able to survive without food or water (They will still want to eat and drink but they don't technically need to), and they can even withstand being naked in outer space as well as re-entering the Earth's atmosphere.