Frog, i disagree. look at the catholic church at the start of the film, which was full of infected, yet they were not attacking each other. why does something kill something else? for food. the infected do not have the mentality to kill due to maliciousness or vengeance, but to infect the uninfected. throughout many parts of the film we see infected reacting to uninfected and not reacting to them, and in that non reactive state they are not attacking each other, not in an attack to kill anyway